Spring comes as the earth quickens its pace toward the cosmic explosion of that young star we call the Sun. Physicists reckon the Sun is merely one of the infinite shards of the Big Bang that took place 14 billion (or so) years ago. Spring’s explosive past makes it only fitting that so many historic wars, especially in the Northern Hemisphere, have combusted into being in springtime, the season of insurrection and resurrection. From Bannockburn to Culloden and from Waterloo to D-Day, battles have bloomed in springtime sunlight.

It seems perplexing and ironic that spring, with its panoply of tulips and newborn lambs, should be so hospitable to bloodshed. Folklore erroneously links spring with human sexuality and fecundity (ergo Easter bunnies and eggs), but it is autumn, not spring, when opportunities for youthful couplings flourish. Love and romance traditionally blushed in autumn (wild oats were sown at harvest festivals), maturing around the vernal equinox, giving rise to the season’s tradition of weddings. Stravinsky captures the smoldering, flaring turbulence in “The Rite Of Spring”.

In the realms of human and biological life, spring is far more apt to be the scene of conflict rather than of peace. In contrast to the other seasons, spring is uniquely violent and confrontational. Like the asymmetry of many wars, the non-linearity of the earth’s orbit seems to catch us off-guard. For most of the year, strife is nature’s norm; only with the arrival of the dark, cold days of deep winter does it pause to catch its breath and nurse its wounds.

We might regard war as one of mankind’s enduring achievements, one that originated with the emergence of our species. But nature has been a theatre of war for the planet’s 6 billion years of existence. Life—human, animal and plant—is a byproduct of an ancient worldwide war waged between protean life forms. The combatants were simple, primitive organisms, myriad groups of archaea and bacteria. The stakes were the ability to harvest sunlight, the greatest prize in cosmic history.

The “Great Photosynthesis War” commenced when early bacteria were attacked by predatory protoplant cells. The combat, lasting millennia, resulted in a treaty, a classic compromise between the protoplants and the bacteria, and chloroplasts were the outcome. With their introduction, the “nation” of organic carbon was born, and quickly spread across the face of the earth. Sunlight was the primordial war’s deciding factor. No doubt the crucial moments in the biological battle came in spring, when, as today, the sun reaches toward its highest point—the longest day.

Military history is rife with springtime scenes of dawn battles. The light is better and lasts longer. In the dark of night, or drear of winter, it is difficult to see, much less hit an enemy. In war, night is best utilized by keeping your enemy awake; the origin of psychological warfare commenced by disturbing the dreams of generals, so that, come first light, the sleep-shorn commanders would be less commanding, yawning the day’s battle plan to their weary troops.

From the standpoint of strategy, initiating the battle at dawn allowed for a longer day, and commensurately more carnage: such is the calculus of war. As it was in the microbial beginning, one side wants what the other possesses. We seem to have learned little from our understanding of plant evolution’s symbiotic outcome. Diplomats and generals should study biology.

The dynamics of man-made wars, ancient and modern, are a distant mirror of the establishment of symbiosis in living organisms. This ancient bacterial war that led to human life is reenacted and memorialized each spring by the arrival of the first green shoots of spring. It was only a few billion years ago that the First Earth War exploded across the primordial seas, a marine conflict that resulted in what scientists call The Great Oxidation Event, and which caused in turn that phenomenon we call life.

This spring as we admire our emerging plants, waxing with energy, let us remember our shared paleobotanic ancestors. Let us calm our raging tempers and still our quickening blood. As the world’s great religions assert, within the specter of war resides the glow of peace, whether we are in meditation, at the sacrificial altar or before the cross. We can, as we stand in the light of day, choose the good or the evil, life or death, the sword or the plowshare.

Grab a hoe.

Among the earliest visitors to their gardens each year are Americans of Irish extraction. Undeterred by the blustery wind and cold, shovels in hand, they are observing the proud tradition of planting potatoes on St. Patrick’s Day.

Many Americans know how the failure of the potato crop between 1845 and 1852 caused mass starvation and disease in Ireland, precipitating a huge wave of Irish immigration to the United States. Since then, America’s Irish immigrants and their descendants have contributed mightily to every field in this country: politics (two presidents), law, industry, science, scholarship and the arts.

The Irish people—and their tragedy—have likewise had an extraordinary impact on the potato. The history of the potato—or to call it by its technical name, Solanum tuberosum—begins in the northern Andes, the mountainous terrain spanning Peru, Ecuador, Colombia and Venezuela. For millennia, the potato was a staple food for the region’s indigenous Inca. By the time the Spanish explorer Francisco Pizarro arrived in 1532, the natives were growing a diverse and multicolored assortment of the 200 potato varieties. Like today, potatoes thrived in the elevated regions of the subtropics, where the climate resembles a cool Canadian summer.

Europeans failed, at first, to grasp the potato’s culinary and commercial promise. To the European mind, root crops were somewhat—how do you say?—less estimable vegetables than their aboveground herbaceous cousins or grains. It was Europe’s superstitious common folk who comprised the anti-potato crowd, while French and Italian aristocrats prized the potato as a delicacy, and “earth truffle” and “earth apple”. Court ladies adorned their hair with tiaras of potato blossoms in their hair, a decorative flourish due for a revival.

Back in South America, the Spanish conquerors saw another kind of potential in the potato. Far from being a delicacy, they saw in the compact, long-lasting and nutritious tubers the perfect slave food—a single potato providing sufficient fuel to sustain a native miner an entire day. Colonial British spies took note: marveling at the potato’s productivity and potential as a food source. Before long, the English operatives relayed the news—and doubtless tubers as well—back to England.

Ireland was Britain’s original colony. Seventeenth century English and anglo-Irish landowners saw the spud as the ideal crop to feed the Irish peasants who labored on their estates under conditions akin to slavery. Potatoes, the estate owners rightly reckoned, were cheaper to grow and process than grain, while Ireland’s cool, cloudy summers provided the optimal climate for the potato to thrive. Introduced in County Wicklow around 1640, it was only a few decades before the large, lumpy type of potato became Ireland’s dominant food crop, especially in the populous south. Ninety percent of the Irish depended on the potato as their primary means of subsistence and livelihood.

The adoption of the potato in Ireland gave rise to one of history’s dark ironies. Until the fatal blight, Irish peasants thrived on their diet of fresh and earthy potatoes, on average consuming five to ten pounds per day. The British, meanwhile, disdained the potato, one of nature’s perfect foods, sticking to a nutrient-poor diet of aged meats and processed grains, such as flour.

The introduction of potatoes caused a dramatic spike in the Irish birth rate. In 1800, Ireland’s population was four and a half million. When the Great Famine began, in 1845, Ireland’s populace numbered 8 million. The diet of potato and dairy products improved Irish health so that, the Irish literally dwarfed the English, the sturdy Celts growing into the “Irish giants” of fact and fiction. The increase in Irish stature, strength and numbers were accompanied by a dramatic decrease in the country’s infant mortality, with six to ten children in the average family.

Originating in a remote valley in Mexico, a pernicious strain of the fungus Phytophthora infestans set sail for Europe with devastating effects. On landing, the resulting disease, called blight, traveled quickly throughout western Europe, beginning in 1845. During the unusually cool, overcast summers of 1846 and 1847, the fungus’s prodigiously infectious spores rode the moist winds. As many of the several dozen potato cultivars in use were related, the fungus ravaged the crops in Ireland and across northern and central Europe. Poland, for example, was only somewhat less hard hit than Ireland. The land-locked Poles starved en masse, while the Irish had had some access to the seas.

The potato, once a godsend for the Irish, became their country’s curse. The Great Potato Famine killed over one million Irish through starvation and disease: more than 12 percent of the population. The acute food shortage and grim prospects caused millions of Irish to emigrate to North America, in search of a better life, surely, but also simply to survive. By 1900, Ireland’s population was down to 3 million, from its peak of 8 million in 1840.

Desperate to explain the wave of destruction, growers and farmers blamed themselves, the soil, the British—even Satan. Part of the most prosperous country in the world, the Irish had solid reasons for holding the British to account. British landowners continued to export grains and livestock from their Irish lands, even as their tenant farmers were dying en masse. A half-hearted British initiative to import American corn to Ireland only slowed the death count, corn lacking the potato’s exceptional range and richness of nutrients.

The 1860s saw a spectacular rebound of Ireland’s potato crop, after Irish and British agriculturists discovered the remedy: breeding new plants from the potatoes that had survived the deadly blight. Out of Ireland’s laboratory of death and misery, tragedy begot triumph. Historians regard the Great Potato Famine as a pivotal point in the evolution of scientific agriculture, helping lead to work like Mendel’s study of garden peas in the 1860s, the science of genetics, and modern agriculture.

In How the Irish Saved Civilization, Thomas Cahill convincingly contends that Irish monks conserved the roots of western civilization. The Irish deserve recognition, too, for their role in conserving one of the world’s greatest food crops, and the horrific sacrifices and suffering that preceded their discovery. On St. Patrick’s Day, let’s remember both the tragedy and triumph of the potato’s epic history in Ireland.

Sometimes everything falls into perfect harmony. Like a safecracker opening a massive vault, the management of America’s best and largest flower show pulled off a huge score, as much a tribute to departing president Jane Pepper as to the maturing skills of the recently appointed Sam Lemheney, the show’s director. And perhaps it augers well for the new president Drew Becher. In any case, The 2010 Philadelphia Flower Show is an exceptionally welcome spring pleasure for the public—and I suggest you go this weekend if you haven’t yet. It is worth every penny. Besides, the funds go to the worthy cause of greening urban landscapes across the state. Consider the ticket cost an investment in beauty.

Certainly, beauty is abundant to a degree unusual compared to years past. Two reasons: the lighting was improved and the show’s theme was ideal for a flower show—Passport To The World, resonating with gardens both past and present. Since the show touched every region of the world, it was never boring. In fact, it was uniquely stimulating. A great theme is a powerful tool for designers.

Highlights include a perfect South African exhibit that included a transcendently beautiful giraffe, impressive lion, fantastically constructed parrots and an astonishing series of African tribes. The American Institute of Floral Design in Baltimore won “Best In Show” and “People’s Choice”—well-deserved slam-dunks. This exhibit is the best I have seen in many years.

New Zealand might lack a bit of uniqueness in their native cultivar selections, but way more than makes up for it with a lush and deeply satisfying display of plants, shrubs and trees that perfectly captures the nation’s strong garden spirit. New Zealand should be on every gardener’s “bucket list”. The highlight, to me, was the large, exotic, hot-water and bright bronze sculpture of a weird lizard-like fish amidst the intense plant displays, all perfectly well lit.

I admired the playful work of the folks at Schaffer Designs. They created my favorite last year, an undersea Mediterranean god’s fantasy world, like a hallucination of your favorite 1960s Italian restaurant grotto. This year they tackled the Arctic with “Polar Fantasy”, a multi faceted and dynamic design with a thoughtful nod to climate change. However, the design’s the thing here—and Schaffer pushes the florists’ materials envelope like no one else at the show. It’s both beautiful and strange—a great combination.

Another favorite was Irwin Landscaping of Hockessin, Delaware’s “Atlantic Highway—Maine to Florida”. My kind of small exhibit: dynamic and fun. The theme is a softball to the Irwins, who bash it out of the park. It features a hilarious lobster with Italian pepper claws (they do look like them), and a crazy alligator x fisherman hybrid with an amusing shrimp on the line. Terrific!

B+ exhibit area displays include Outerspaces of Paoli, Pennsylvania’s simple, elegant and sexy spa; Doylestown’s Mark Cook Landscaping and Contracting’s perfectly proportioned azaleas set about an oddly twisted garden shed that looks like an empty fairytale foster home for trolls. Ponds and Gardens of Limekiln (Glenside, PA) make a droll beer garden come to life, edged appropriately with many cultivars based upon the great plant collectors of early 20th century Germany. The pond adjacent to the “bierstube” does not fit well, but everyone else likes it, so there you are.

Solid “B”s include Moda Botanica’s shipping containers—a daring treatment of the cutflower trade’s ubiquitous but unknown world: the flowers’ journey from field to shop. It is well done here, overdone there, and superb in one inspired section: a winding lattice-like “escape” of brilliant scarlet/orange edged gloriosa lilies scampering through the rough looking graffitied, box-car-like exhibit. Indeed, like the gloriosa lilies, the entire display gives new meaning to the phrase “over the top”. Check it out.

Another solid “B” was the seductive bamboo grove by Michael Petrie Handmade Gardens, he of the strange and wonderful painted trees last year. Intentionally dark, in a dark hall, the hidden cultivar displays set beneath the handsome bamboo are sensational, but difficult to see with the weak flashlights provided in plastic buckets at the entrance. The “night” effect was, therefore, a bit flat. Could have used an LED full moon overhead. I wanted to like it more but my eyesight is not quite good enough, especially after becoming adjusted to a well-lit show.

No mention of the main exhibit hall is complete without Jane Pepper’s “well-wishes” display from her native Scotland. Sweet, whimsical and made with love, it is a delightful and uplifting design, meticulously well executed, and a fitting testament to a classy professional and great leader of the PHS for 29 years.

In the “middle” area, where non-profits mingle with judged specimen displays and both surround a new, deluxe PHS information, display and question desk, the stand-outs include The Mid-Atlantic Horticulture Therapy Network, with their simple, clear and well-staffed booth; Camden City Garden Club’s excellent plant displays and Campbell’s Soup tank (ha ha); W.B. Saul High School’s strikingly handsome Statue of Liberty; and Temple/Ambler’s excellent, informative and interestingly constructed urban ecology exhibit. Finally, Bartram’s Garden at the Fairmount Park’s display showed the many Philadelphia native’s greatest treasures from his exploration trips.

The flower and plant judging areas include some spectacular Begonias this year, as well as Clivia and a few breathtaking Cacti and Orchids. All of the entries were very well grown—a tough job in this unusually dark, harsh winter.

Very little, alas, was new in the Market Place. Hand-made honey soaps and artisanal vinegars are no longer new. Potpourri drives this dog off his gut-wagon every time, and I also walk briskly by what I call the “angst sculptures” of shiny, happy families.

On the other hand, there are several local rare plant nurseries, such as Agro-Plants, and something called the “Texas Tomato Cage” nearby Landreth Seeds’ booth, and a wide and deep table of mainland Chinese knick-knacks like those I used to see in Chicago flea markets as a boy. I felt nostalgic. I am an old-fashioned Chinatown junkie, so to speak. I could swim down a river of cheap little wooden toys.

Also, it was nice to see our friends at Cobrahead Tools and duBarry of Ireland boots, my favorite leather Wellingtons and a bargain, believe me.

Last, but not least, the Samba dancer was so good she gave me a wild case of vertigo.

Can’t wait for next year!

If you haven’t gone, GO. It lasts through tomorrow and all day Sunday.

Most of the time, the garden is a quiet place, an idyllic refuge from the madding crowd. The loudest noise is usually the gentle buzz of bees or hum of hummingbirds on nectar-gathering sorties. Once in awhile, though, a controversy will alight amid the flowers and vegetables, the garden gloves come off, and, before you know it, the dirt is flying.

In the 90s, there was a showdown regarding hybrids versus heirlooms. The heirloom faction championed the mostly old, late, but flavorful cultivars with romantic names, and portrayed hybrids as a plot by Big Agriculture. In fact, the hybridists were improving the heirlooms for increased flavor, vigor and yield.

Soon another controversy arose. Exotic species from abroad were being introduced to America’s gardens. The nativists saw the foreign introductions as alien invaders, potential monopolists that would crowd out our indigenous plant life. The exoticists, on the other hand, cherished their rare species, gathered by intrepid plant explorers. Both controversies rage on, with no end—or middle ground—in sight.

Normally, in the winter months gardeners serenely peruse nursery catalogs and order seeds and plants for the coming season. This year the placid annual rite was rudely interrupted by an article in the Atlantic Monthly. Gardeners flung down their catalogs, sprang from their couches, and marched, if not to the barricades, to their computer keyboards to transpose their howls of dismay in upper case letters.

The perpetrator of the outrage is the writer Caitlin Flanagan, who in her January piece did a slash and burn number on the School Garden Movement. The article, posing as a review of the 2007 biography, Alice Waters and Chez Panisse by Thomas McNamee, gives the book scant mention, preferring to cast asparagus on Waters, the celebrated chef and progenitor of the contemporary School Garden Movement.

In her piece, “Cultivating Failure,” Ms. Flanagan contends that the School Garden Movement exacts a terrible cost on California’s cash-strapped, dysfunctional school system. Underperforming students, especially from minorities, are, she maintains, squandering precious time growing arugula, when their energies would be more profitably engaged in studies of math, science and literature.

In her opening salvo, the writer imagines the child of a migrant laborer, a naturalized American on pace to fulfill his father’s dream of a better future for his family. Then, on the first day of middle school, he “heads out to the field, where he stoops out under a hot sun and begins to pick lettuce.”

As the reader mulls the darkish ironies of this scenario, and the luxuriant infelicities of Flanagan’s prose, the writer’s klaxonlike voice yanks us from our reverie and flings us into the thickets of her second paragraph.

Mounting her bushelbasket, the Red Bull-fueled Flanangan declares, “The cruel trick has been pulled on this benighted child by an agglomeration of foodies and educational reformers who are propelled by a vacuous if well-meaning ideology that is responsible for robbing an increasing number of American schoolchildren of hours they might otherwise have spent reading important books or learning higher math (attaining the cultural achievements, in other words, that have lifted uncounted generations of human beings out of the desperate daily scrabble to wrest sustenance from dirt).”

What sticks to Flanagan’s crocs, one suspects, is not the fate of the “benighted” Latino and minority students in California schools, whose American dreams, she feels, are turning into compost in the garden.

Flanagan’s arguments against garden education are really an hors d’oeuvres. For the entrée served up in her piece is Alice Waters, who jump-started the School Garden Movement at Martin Luther King Jr. Middle School in Berkeley, California, where students, Flanagan fails to mention, spend roughly an hour-and-a-half each week in the garden. She is out to pillory Waters and the largely left-leaning idealists crusading to introduce garden education to American schools.

Decrying garden education as a “giant experiment” (it isn’t), Flanagan complains, “That no one is calling foul on this is only one manifestation of the way the new Food Hysteria has come to dominate and diminish our shared cultural life.” Huh?

Proponents of the Slow Food Movement and school gardens may, at times, sound preachy and precious. Reformers like Ms. Waters have provided ample targets for writers like Dickens, George Bernard Shaw, Nathanael West and Tom Wolfe. However, today’s food crusaders merit a sharper satirical knife than that wielded by Flanagan.

Yet, Ms. Flanagan has done the School Garden Movement an enormous favor, bringing welcome attention to the food fight and rallying the troops, who lit up the blogosphere with their denunciations of her piece.

Gardening surely merits a place in the school curriculum. Rather than be an adjunct to a student’s course of studies, gardening can serve as a hub where multiple disciplines converge. Consider the University of Wisconsin‘s innovative but less well known “Fast Plants” school programs. No blistering sun required, and their instructional value is unparalleled.

Furthermore, gardening is unique in how it involves and reflects multiple academic fields. One can study literature, history and mathematics by way of the garden. Furthermore, the science of the garden itself can be investigated from the vantage points of botany, biology, nutrition, ecology, evolution and astronomy.

Plants and seeds provide students with new ways to understand the world and their place in it. A small, modest garden supplies tactility, shape, color, fragrance and flavor: all key ways we apprehend reality. Finally, gardening provides an overarching narrative that connects and unites all aspects of humanity. Nothing to rail against.

It is difficult to grasp the scale of destruction, death and horror visited upon Haiti by the earthquake that shook the island country on January 12th. The estimated death toll–upwards of 200,000–is staggering; if the United States were to have a disaster with proportionate casualties, the loss of life would top 6 million.

Military and humanitarian support have poured into Haiti to rescue victims, care for and feed survivors, and devise how to resurrect a country acutely in need of development before the earthquake struck.  The “global village” has shown exceptional generosity and compassion for this fragile land and its hard-hit population.

Governments and NGOs are now joining forces to help not just rebuild Haiti, but to help engender a new future for the troubled land. There is bold talk of a Marshall Plan for Haiti, which will replace its tattered and dysfunctional infrastructure with institutions and services that come closer to meeting the ordinary peoples’ needs.

Today, the Haiti earthquake, a disaster unprecedented in the western hemisphere, is already fading from the headlines and airwaves. The TV cameras and army of journalists are heading home. The networks and newspapers have deemed that the public’s appetite for this disaster is sated.

This partial eclipse in public attention will be mirrored eventually in diminishing material support for Haiti’s relief and reconstruction. Humanitarian organizations, NGOs and underdeveloped countries are all too familiar with “donor fatigue” and “evaporation”, the latter term referring to promised funds that arrive late, only in part, or not at all. Financial aid to poor nations can be diluted–or washed away–by government corruption, or it can sit in limbo, as governments often lack the administration or distribution network to provide aid where needed.

Certainly rebuilding Haiti will require money, and lots of it, together with expert guidance of all kinds. Many of the rebuilding programs will be hiring Haitians to do the work of clearing debris and constructing buildings–sturdier, safer and more sanitary–from the rubble left by the earthquake. It is vital that Haitians be involved at every level of rebuilding their country.

When it comes to helping Haiti, I have a small idea, that might be a big idea.  In all the plans and proposals for Haiti I have read, one key catalyst for Haitian renewal is missing: seeds. Distributing vegetable and fruit seeds to Haitians can be a simple project, one that can be implemented quickly, easily and inexpensively. A Seeds for Haiti program can accomplish things that infusions of dollars and flotillas of experts cannot.

Seeds, of course, are not a cure-all for Haitians’ woes.  What seeds can do is help families feed themselves, provide a vital source of nutrition and help bring in income. Haiti, like many other poor nations, has been hit hard by rising food prices. Malnutrition is rampant, evinced by the red-tinged hair of undernourished children. In a country where the average family income is $100 a year, a small garden plot might itself yield a hundred dollars worth of fresh, nutritious produce. As American gardeners will attest, the return on the investment in seeds is unsurpassable.

A seed relief program provides another key benefit. It gives Haitians a small measure of control over their own destinies. The distribution of seeds is less prone to donor fatigue and evaporation; seeds are far less likely to be pilfered than dollars. The seed program, once put in place, can carry on without significant government or NGO involvement.

Seeds have a strong track record when it comes to building and rebuilding societies. Civilization was born in gardens ten thousand years ago or so. The birth of agriculture helped settle families, engender communities and develop states and governments.

Our company has been involved in numerous seed relief programs around the world, including Haiti.  We have participated in seed drops in other troubled countries including Iraq, Bosnia, Rwanda and Somalia. The seed drop in Rwanda, done together with CARE, followed the 1994 genocide. The largest vegetable seed relief shipment ever conducted, the Rwanda seed drop helped 1.7 million people.

David Burpee, the founder’s eldest son who led the company for a half-century, liked to quote a Chinese proverb: “If you want to be happy for an hour, get drunk. If you want to be happy for a weekend, get married. If you want to be happy for a whole week, kill your pig and eat it. But if you want to be happy all your life, become a gardener.”

Seeds, surely the ultimate symbol of renewal, offer a fresh opportunity to Haitians to help regrow their country themselves, from the ground up. And we’re ready to help.

This coming Sunday, February 28th, I shall give a speech at 11:30 A.M. at the Philadelphia Flower Show. Since this year’s theme is “Passport To The World”, we decided to focus on plant collecting. My talk is about one hour long, including a question and answer session. I shall speak off these “talking points”, so there will be much more than what you read here.

On Thursday, March 4th, at 10:30 A.M., Simon Crawford, our European Representative, will speak on new and unusual vegetables.

I hope you can make it!

PLANT COLLECTING PAST AND FUTURE

What is “plant collecting”?

1. First — “collecting”

   Roots in hoarding — ancient custom of hedging against shortages resulting from war, famine, disease, cold, drought, flood, etc. Resonance in history, such as story of Noah’s Ark.

   After scientific revolutions of the Enlightenment and subsequent Industrial Revolutions, Political Revolutions, Transportation/exploration Revolutions, “Collecting” changed. In a general way, collecting became a form of “manifesting” things that were discovered in space and over time. Specifically new things deriving, literally, from an expanded universe. The stage was set by the following factors:

   • — Prosperity reduced causes for shortages and thus, collecting-as-hoarding
   • — Collecting became a strategy of science; as science exploded, so did collecting, reaching the zenith in the Victorian Era, especially in England. Nevertheless, the French and Germans were also prodigious collectors
   • —What we know to be “modern” collecting is the “wide amassing of a genus”, for example, or any other “type” of object
   • —Exploration
   • —Cross cultural fertilization (masks in art, for example)
   • —Acquiring “man-made” things becomes part of an upper class “hobby tradition”

   Later, collecting became highly sophisticated, and a sort of “secondary”, home-based level of collecting appeared. It is best to call it “cataloguing” as well as “collecting”.
   They include:

   “Completist collectors”—those who collect for modern institutions, such as museums

   For individuals such as “collectors” of all sorts today
   art, books, antiques, guns—these are all “completist” oriented. However, many people buy or “collect” a few objects because of their association, memory or as a status symbol.

   “The Original Collectors”

   Royalty, secular and religious, but in our age mainly secular. They have a sameness—in that they are large, and eventually established as institutions. They collect based on:

   • Cultural pride
   • National pride
   • Individual enthusiasm
   • Aesthetic interest
   • Historical interest

   —Based upon technology

   • The individual, and in particular, the middle class, or in our case
   • average citizen with discretionary income, began to take up “collecting”.
   Family activity
   • Individual hobby — great age of factory multiples = great age of collecting
   • Stamps, coins — virtually the quintessential “common
   • mans'” completist collecting hobby
   Baseball cards — now children enter the game
   • Lladro figurines
   • Popularization and “vulgarization” i.e., camp and kitsch — collections of things that were not meant to be collected, i.e., junk.

   Then, in the late-modern era, as travel became quicker, easier as well as less expensive, our contemporary explorer and collector took culture shape.

   Exploratory “collecting” — more scientific and less completist, though still having many completist-oriented collectors. Let’s focus on the natural world now, since it will lead us to the world of plants and plant collecting.

   The natural world is essentially exploratory or discovery-oriented, because of its natural origin. The earth is its scope. Nature is not a multiples factory, although many view it that way. One could say that the earth produces gems, but it is different, in an important way, as follows:

   • Nature is an Open System
   • Technology is a Closed System
   • This makes nature-oriented collecting inherently more fascinating as well as more challenging in terms of the manner of going about it.
   • Butterflies, insects, bird-watching (actually a type of collecting), tropical fish, and most of all, plant collecting.
   • The Ultimate Collector’s Quest — Where does “plant collecting” rank in human history?
     1. Holy Grail
     2. Sunken Treasure
     3. El Dorado “city of gold” precious minerals
     4. Spices and Herbs, i.e., new plants
     5. Fountain of Youth

   These are the top 5, and we made it. What is interesting is what is not on the list: slaves (no one had to look for them), wood, metals, secret knowledge, God—these were among all things the “known world” already had, or at least had within reach. So, it is very interesting to consider what they searched for; to gain an insight into what they did not have, but thought they could find, and also wanted so desperately that they were willing to sacrifice their lives to get it.

2. “Plant Collecting”, per se.

In order to understand plant collecting, let’s spend a moment on plants. We should recall that plants—in the form of seeds, cuttings, roots and herbs, mainly for spices, which is just another word for flavorings—are the only living organism to make the “top 5” list of most-sought-after things in the modern world. So, therefore, plants occupy a unique place in civilization: they are a confusion of both discovery or exploration on the one hand, and collection, classification and maintenance on the other. No other living thing has this quality. Why? Because, once collected, they have to be kept alive.

Plants change in the natural environment profoundly over time. We do not always notice, either because we are absent, or because the changes are too small for the naked eye. Therefore, the plants we collect must be closely examined upon arrival, so to speak, as well as periodically over generations of their lives. Plants in their new environments undergo even greater changes. This is the essence of evolution.

Hence, the need for the garden. A garden is a protected place for plants. It differs from an agricultural field almost as much as it differs from the wild. This is why gardens are so small—they are homes for typically small things. For the scientist, collector and plant lover, gardens are equally ideal. Plants need to be tended, regenerated and protected in order to yield knowledge for the scientist, status for the collector and pleasure for the amateur. Often all three are the same person. This was actually the case with Luther Burbank, Atlee Burpee, Norman Borlaug, Claude Hope, Charles Ricks and Wilson Popenoe, to name just a few of the great plantsmen of the past 100 years.

Now, let us focus on the latter—the plant lover, including all of us in this auditorium today. What makes us love plants so much that we collect them?

Good question! There are several answers:

1. The appearance of the plants in our yard or around our home. This may seem too obvious, but let’s look more closely at the last word, “home”.
2. It was Gertrude Jekyll, the architect, who with Edward Lutyens, made the modern breakthrough in home gardening. She put forth the notion that the house and the garden should never again be considered separately, but as one and the same. Before Jekyll and Lutyens a home or estate or cottage was divided into two distinct and utterly separate halves. It was gospel, it was even imperative (and in many places still is) that the house be considered apart from the garden, or grounds, and the garden be considered independently of the house. Jekyll changed all that. She spent over a half century career promoting the profoundly simple yet revolutionary idea that they must be considered as the same, as a blended whole. She and Lutyens said they not only complement each other, but actually combine and become a “third” or transcendent entity: the home formally redefined.

• —Jekyll’s impact on plant collecting

• She introduced a new level of scrutiny, a new attention to how plants conformed to the new “look” of the new “whole”. Thus, she experimented, as all great innovators do. She introduced new plants that had unusual forms, shapes, sizes, and—most importantly—colors, that would blend with the new types of cottages and domestic buildings that Lutyens was designing.

• —We may call it “the past”, but it is still “the future”. Contrasted against the architecture of the late 20th century, the homes of these two innovators look futuristic. They emphasize human proportions, they limit rather than impose the size of the houses, and encompass the entire yard into the garden—the whole property is a garden, with a house or cottage at its center. This is actually the new movement in early 21st century garden design. Look at Julie Messervy and Sarah Susanka’s work. It is exactly the same idea as Jekyll and Lutyens.

• A few rules:

• Remember, first, that a “new” plant is one that you have not grown before. It is remarkable how the same plants can change appearance and “feeling” from garden to garden.
• If you decide to collect vegetables, be aware that they have challenges distinct from perennials and shrubs, and vice versa. Yet, annual vegetables, as well as flowers, are a terrific way to begin collecting plants. They’re easy, fast and amusing for the beginner. Some people never quit or proceed to shrubs and trees. This underscores the truth that collecting is personal, and always should be. If it doesn’t give you pleasure and soul satisfaction, it will simply be hard work. So, relax and collect what you know in your heart that you like.
• Follow the rules. First, know them. The Interior Department has different rules for plant collecting in the various states. Follow them strictly. Otherwise, you’re a renegade collector, and that is an unnecessary guilt trip.
• Collect for your group of zones or micro-climate. It is fun to “push the envelope” and experiment to see if you can grow a mountain banana plant in a zone 5. But it is wasteful to push too hard, just as it is so immensely satisfying to discover a new plant that is unexpectedly ideal for you, your home, and your climate. A happy plant is like a happy child. It is a precious miracle to behold.
• Experiment not just with “collecting”, but also with “shaping” or forming your collection. I like Pelargoniums. There is no way to do it but to grow them in rows and blocks. That is my style, but others have their own styles. It is fun and interesting to continue to challenge yourself.

Thank you. Any questions?

The modern head cold is the price for an uncovered head. Even in men, bareness—hairy or clean—is thought to be sexy. It originated with the rise of both informal photography and the fashion for the outdoorsy look, culminating in President John F. Kennedy’s famous bushy mane shining in the sun of his 1961 Inauguration. (Ever since, men have shown off their less than beautiful bodies, starting with the top. How else can one explain men’s shorts?)

From the 60s on, men—young, middle-aged and even elderly—have gone hatless during rain, cold, hail and snow, whether to work or play, a fancy ball or dinner party or shuffling down to the pharmacy for Tamiflu. Nothing can get a man or boy to wear a proper fall, winter or spring hat, unless it is a sports cap, which descended from the 19th century lady’s sunbonnet—of all things—and was popularized by baseball players.

How did men get so dumb? Same reason as always. Women like—or say they like—an adult man with a full head of hair. That consists of less than 1% of men. (I exaggerate to make my point.) These gifted fellows—like JFK—started the hatless trend and dragged the rest of us—the overwhelming male majority—along for the miserable ride. Their legacy is the modern cold and flu season and its myriad futile cures.

Baldness has had a few moments in the sun, so to speak—eras when a receding hairline denoted nobility, intelligence and gravitas. Perhaps these used to be attractive to women, too. One would hope, since many females lose their youthful head of hair just as men do. Even balding women, their high receding hairlines bedecked with curls, were viewed as desirable during the 15th and 16th centuries. Unavoidably sexy, I’d say.

This brings me to the broader subject of what I call “personal climate change”. What is this? Take “personal climate”—the change over a course of years in the temperature of your personal being or immediate surroundings—and then note the dramatic “change” it has undergone over the past several decades.

Since the 1950s, two powerful trends have affected “PCC”: wardrobe and indoor temperatures. First, let us take wardrobe. Since shortly after World War II—and stemming from it—the ubiquitous fashion, particularly among the influential youth of these decades, has been to wear T-shirts almost all the time. Although originally intended as an undergarment to keep a person warm, the T-shirt became an outer garment to keep sailors and other soldiers in the tropics cool. It has now become for most people a standard item of casual dress, whether during winter or summer. Ironically, the prevalence of T-shirts among the populace serves to heighten—not lower—the perception of unusual warmth when exiting an air-conditioned building.

Which brings me to my second point. I had a visitor from the UK last summer who told me how amazed he was that so many Americans wear T-shirts all the time. To my “So what?”, he replied, “Well, it’s very cool indoors, George.” “Aaah”, I sighed with my new insight. Forget about how hot you get outdoors with so much skin exposed to the sun. Forget about raising your risk of suffering from skin cancer. Think only about how cold you can get at your office building in July, or at a mall, restaurant or movie theater. Witness, then, the birth of the summer cold. Plus, voilà! Man-Made Personal Climate Change or “MPCC”.

Therefore, I further submit that we have developed, over the last half century or so, an unconscious, or involuntary, sensitivity to outdoor temperatures during the warm and hot annual seasons. This unconscious receptivity reinforces a conscious psychic satisfaction derived from believing in man-made global warming. It feels good to believe in something you can change from “bad” to “good”.

Back in the 70s I had many spirited youthful discussions with friends about a new ice age. “What did we have to do with it?” was a common topic. Having already travelled widely by the time I was 16, I was skeptical that humans could change the course of such things as even regional climates, much less the earth’s climate. The obvious exception was a large city. I thought it arrogant and hubristic to fancy that we were so powerful a species as to be able to alter the oceans and atmosphere. It seemed a bit “flat earth” to me as well, in the absence of solid data. In the 70s, our anxieties, if any, concerned ICBMs. Mostly, however, we worried about getting a job.

In any case, the new mini Ice Age that was theorized in the mid-70s never came about, likely due to the same realities that make the planet unresponsive, even immune, to the most sophisticated computer models. Galileo and Newton had no computers, and they made great progress, so why should The University of East Anglia or the UN have made any better progress?

Rather, what has animated the debate is the sense that the world can and should be changed for the better, and science can lead the way. However, I propose an important new twist: the very public the scientists wish to persuade is unconsciously predisposed to believing them, due to their barely conscious “micro-responses” over a long period of time to real changes in their sensation of the outside temperatures, relative to inside temperatures.

Keep in mind that not everyone leaves Washington, DC in the summertime. Many policy-makers live and work in the inferno that is DC from late April to late September. I believe my theory is hiding in plain sight. It doesn’t explain everything—and I do not dispute climate change. But “MPCC” might add something to the debate about the degree of man-made causes, and the degree also that the public may go to accepting their existence. After all, it feels very hot when you wear a T-shirt all day in an air-conditioned office and then step outside into even the slightest muggy weather. “Something must be wrong” says the unconscious.

Still think I’m kidding? Consider the now common “wind chill” reported endlessly by television and radio weathermen. As a child growing up in the pre-wind chill days, I knew what a windy Arctic blast was. No one had to split the temperatures into two indices. What useless nonsense! However, folks today are as conscious—or perhaps unconscious—of the wind chill as they are of the thermometer reading. The difference is perception, and that is what I try to address in “MPCC”.

When did air conditioning become widespread? After World War II, same as T-shirts. At first it was movie theaters, restaurants and bars, especially in the South and Southwest. Soon, “AC” penetrated everywhere: houses, offices, cars, even gigantic factories that used to have windows to handle the summer heat. All those beautiful old industrial buildings are gone now.

Does “MPCC” have an impact on the perception—versus the reality—of global climate change? Perhaps so. Most people now live in treeless suburbs. These are becoming more prevalent in the southern US and southwestern US—the sunbelt. I have friends in Arizona who live for six months in what the American novelist Henry Miller prophetically called in 1945, “The Air Conditioned Nightmare.” They wake up in 70° air, enter the 70° air of their car, transit to their 70° office and then retrace the journey at 5:00 P.M. If they go out, it isn’t outdoors, but to an air conditioned restaurant or movie theater. Even the MLB’s Arizona Diamondbacks play in Chase Field, a fully air-conditioned ballpark bathing over 48,000 people in a gigantic cloud of artificially cooled vapor.

If scientists and serious-minded citizens consider the global warming phenomenon and ask themselves, “Is our environment becoming hotter?”, they might come to a positive conclusion a bit more often if they were raised in a society that has shielded them from normal exposure to summer’s heat.

Most people would think this idea bizarre. However, remember “wind chill”. The perception of the temperature is often different from the measurement of it. When accustomed to cool air, any warmth is “hot”. Therefore, it may not be a stretch to consider that our receptivity over the past 30 years to the veracity of the global warming trend would be caused by the fact that we actually experience the outdoors as being warmer now than what we felt as children.

Even in antiquity there was an awareness that plants influence the growth of their neighbors. The earliest reference comes from Theophrastus (called the “father of botany”) who, roughly 2300 years ago, noted that chickpea killed weeds and depleted the soil. He might have been describing what we call “allelopathy”, the phenomenon in which a chemical produced by one plant interferes with the growth of another.

The classic example of allelopathy that is familiar to most gardeners is black walnut (Juglans nigra). Black walnut and its close relatives (butternut, Juglans cinerea, being one of them) release a chemical (juglone) that causes susceptible plants growing near it to yellow, wilt, and die. Juglone is present in all parts of the plant and is the staining, brown pigment in walnut hulls. Solanaceous annuals, such as tomato (Lycopersicon spp.), are especially sensitive to it.

There are good reasons to study allelopathy. One is the search for natural compounds that rival synthetic agrochemicals in efficacy and perhaps trump them for environmental and human safety. Another is breeding allelopathy into crop plants to suppress weeds, as in the case of rice where there is evidence of natural allelopathy.

However, allelopathy is controversial and not well understood. Demonstrating that a plant chemical has a clear biological effect in nature is difficult. Test conditions will strongly influence any experiment designed to investigate allelopathic activity. Also, there are innumerable interactions that can occur in the soil. A compound can be metabolized and inactivated by soil microorganisms. It may be irreversibly bound to soil particles, rendering it null. It will certainly become increasingly dilute the farther it diffuses from its source. All these variables and others need to be explored and controlled.

A further complication is that plants also interact through competition for limited resources, mostly light, water, and soil nutrients. The manifestations of allelopathy and competition are similar. Sometimes they are identical. To demonstrate allelopathy, an isolated plant compound must be toxic to other plants even when interactions such as competition are removed, and any experimental design that separates allelopathy from competition may be unnatural.

A persuasive, but false, instance of allelopathy involves purple sage (Salvia leucophylla), a herbaceous plant that grows in the southern California coastal scrub plant community. Beneath and under purple sage are zones of bare ground (“halos”) where apparently no plants can grow. These halos were theorized to be caused by the allelopathic effect of volatile compounds emitted by purple sage. Laboratory work supported the hypothesis and confirmed that isolated purple sage compounds were biologically active and inhibited seed germination. These results were assumed to apply in nature, and the work was published in Science, the most prestigious scientific journal in the world. A photo of plant-free zones around purple sage highlighted the article on the issue’s cover.

A competing theory postulated that small birds and rodents seeking protection from predators hide beneath purple sage and, feeding on seeds and seedlings, create and maintain the zones of bare ground. Several years after the Science article appeared, a graduate student fenced plots of purple sage to exclude birds and rodents; seeds readily sprouted and grew to fill the bare areas. Thus, science is rarely settled or “QED”.

There is strong evidence, though, that allelopathy or something like it plays a role in the success of invasive plants. Garlic mustard (Alliaria petiolata), which must now be familiar to all North American gardeners, is an example. The plant is native to Europe and was first reported in North America on Long Island, NY, in 1868. It has since spread across most of the USA and much of Canada. It is a threat to native plants, and the animals that depend on them, in forest plant communities wherever it grows.

In a couple of growing seasons, garlic mustard is able to suppress and displace many of the plants that live in the forest understory and at its margin, including seedlings of the dominant canopy trees. It becomes far more abundant here than in its native range in Europe. There it is a weak competitor only and coexists with many of the same plants that it so successfully outcompetes on this continent.

What accounts for this difference? At least two basic possibilities exist to explain the success of invasive species in general: there is weaker opposition from other species in the new range than at home, and the invasive plant has stronger effects in the new range than at home. For garlic mustard, both may play a role, but the second possibility is the key. Garlic mustard has novel compounds that are particularly destructive to mycorrhizal fungi here in its new range.

Most vascular plants form mycorrhizal associations in which fungi grow within or in intimate contact with plant roots. These are mutualistic relationships that involve symbiotic nutrient exchange; fungi “feed” plants minerals and water, and plants provide the fungi photosynthetically derived sugars. Many plants, but not all, are dependent (some highly dependent) on these associations for growth and survival. The herbs and woody perennials found where garlic mustard is so successful are especially dependent on these fungi.

Experiments show that garlic mustard grown in U.S. soils decreases the concentration of resident mycorrhizal fungi. When North American plants are sown to this soil, the mycorrhizae-dependent plants do not germinate. The grasses and sedges that are not so dependent on fungi grow essentially normally. Garlic mustard grown in European soils does not change the concentration of mycorrhizal fungi, and when European varieties of the same plants as those tested in the USA are sown to this soil, germination is normal. Purified extracts of garlic mustard added to soil give the same results.

Garlic mustard’s method of success then is not “direct” allelopathy. Rather, by the chemicals it emits, garlic mustard inhibits mutualistic fungi that many of our native plants rely on for survival, and, so, it is able to outcompete these plants. In Europe, the fungi that coevolved with garlic mustard are not sensitive to these chemicals, and the explosive growth that epitomizes garlic mustard’s invasion of the USA is checked.

Of course, plants are rooted in one spot. Where animals can range far and wide seeking water, food, and companionship, plants cannot. Yet, in their own way, plants are every bit as dynamic as animals, maybe more so. They respond to their environment rapidly and reversibly in ways that could be termed “behavior”. This is seen not only in plants’ ability to sense up and down or where light comes from but also in their capacity to manipulate their environment chemically. Plants use an astonishing array of chemicals to influence their world, from defense against “enemy” plant pathogens and herbivores to acquisition of nutrients. What we call allelopathy is just one facet of this. Our conception of allelopathy—as discrete and unconnected with the numerous other chemical interactions that plants engage in—is artificial and limits our ability to model and clearly understand allelopathy.

To use a current word, allelopathy is more “nuanced” than we thought. It is not a single mechanism or plant function; it’s an expression of many. There is at present active work on allelopathy in many plant science disciplines, ecology and weed science to name two. This is a good thing. The more we regard allelopathy as part of a larger puzzle, the more we will understand it. Theophrastus would probably approve.

Next week we might remind ourselves that love is not rocket science. No, it’s way more difficult. Albert Einstein put the question, “How on earth are you ever going to explain in terms of chemistry and physics so important a biological phenomenon as first love?” We are still waiting for his answer.

I would imagine, should one gaze into the brain of a rocket scientist, on display would be a highly functioning organ, operating optimally, neurons synchronously firing away, circuits lit up—the Rockettes, if you will. But when we embark on love, our brain’s physiology runs amok, leaving a trail of wine, chocolate, flowers and broken hearts. Happy Valentine’s Day!

Considerable research has been done on the neurophysiology of love. The findings convey a colorful, if disquieting, notion of love’s effects on our brains. Love doesn’t come plastered with a warning label, which is a shame: it would make engaging reading.

The passion of first love sends our bodies and brains into overdrive, replete with racing hearts, sweaty palms and flushed cheeks. Our euphoria reflects the boosted blood flow in the brain’s pleasure centers, the region where drug addiction takes root. Our minds, transfixed on our beloved, trigger a dip in the brain’s serotonin level, symptomatic of those afflicted with obsessive-compulsive disorders.

Love of a less tumultuous kind takes hold after passion. Romantic love keeps the passion’s spark and chemistry, but is more balanced and sustainable. The brain’s pleasure center still lights up, but the light is not blinding, nor the love blind.

In romantic love, there is mutual affection and respect, shared pleasures, interests and life goals built for 2. With marriage, the ardent lovers transform into devoted partners and parents, the once white-flames of passion give way to a contented glow of nurturing, managing, planning, dance performances and soccer games. The fire? Flickering in the outdoor grill. As Donny Hathaway and Roberta Flack beautifully ask, “Where Is The Love?”

How to rekindle the fires of romance? Not long ago Sherwin-Williams, the paint company, suggested couples might rediscover their romance by, yes, painting together. Wives and husbands, they had learned, split home improvement tasks into two types: his and hers. The company presented home painting projects as a way for couples to reconnect, share some laughs, enhance their home and sense of shared achievement.

Our company, Burpee, using focus groups, found a similar divide when it comes to gardening. “She grows it and I eat it,” and “He grows it and I cook it,” were common refrains. Paradise Lost! Romance stops at the garden gate-precisely where it should begin.

Research demonstrates that when couples share the unpaid responsibilities of the home, the happier they are. I can think of no better place to work as a team than the garden, the home’s true “living room”.

Gardening allows couples to engage in multiple ways. They plan, ready, and lovingly tend their garden. They contend with weather, and a colorful mix of challenges, mishaps, surprises, disappointments and triumphs. Together they admire, harvest and dine on the results. Can’t do that with your laptops or iPhones.

The garden becomes a collective work of imagination. A few steps into your backyard and you’re there: your own spa-theatre-dreamscape-ashram-sensorium-cathedral-oasis-refuge-herbarium-cabinet of wonders. Your joint labor of love is a place of meditation, exercise, natural marvels, spectacle, aesthetic beauty, fragrance and color.

Another thing. The garden is a veritable Shangri-la of romance. Ask any passing bee, dragonfly, butterfly or hummingbird. Want Einstein’s answer? Look out your back door. Love is in the air.

The dog didn’t seem to be cold. I wasn’t either, but it was no warmer than —15°F. It was a clear, still night; we had gone out for a walk before bed and nothing much seemed to be moving. The only sound I was aware of was the brittle, dry snow crunching beneath our feet. As we came to the corner, under the street light, I saw a puddle of water, unfrozen. I wondered at it and reflexively kicked a dusting of snow into it. It froze almost instantaneously from the points of contact with the snow.

Why the puddle was unfrozen in the first place I don’t know. The temperature had been well below freezing for a week or more, so the puddle must have existed for that long anyway. On first glance, freezing water seems like the simplest thing in the world. But a closer look exposes more complexity. The same is true with the interaction of plants and freezing temperatures.

During the course of the year, plants from temperate regions change in their capacity to tolerate and survive freezing temperatures. Very few herbaceous plants can tolerate low temperatures for long; some have little or no tolerance at all. But after a period of cold acclimation, some perennial species are extraordinarily tolerant. Trees native to the boreal zone withstand temperatures of –40°F for months and in midwinter survive temperatures lower than that. But even species that are quite cold hardy in midwinter can be damaged by frost during their growing season.

Everybody knows that ice melts above 32°F. What’s less well known is that pure water (not rain water or tap water) is unlikely to freeze at temperatures much warmer than —40°F; the attribute of water to remain liquid at temperatures well below the freezing point is called “supercooling”. When water freezes, it becomes crystalline, but this transition does not usually occur spontaneously at temperatures warmer than —40°F. A germ or seed that initiates or “nucleates” ice crystal formation and from which crystals grow is required. This is how the snow triggered the puddle to freeze on my walk.

“Ice nucleators” are important, if not essential, in the formation of snow and rain, and they are ubiquitous in the atmosphere. Most are bacteria; a diverse range of bacterial species presumably deposited by snow can be isolated from high mountain peaks that would otherwise seem sterile. Air-borne dust also plays a role in ice nucleation, and some plant constituents are ice nucleators. Water in nature has an abundance of ice nucleators, and so it generally freezes at or slightly below 32°F.

Most plants, even very tender ones, have some tolerance for cold temperatures, and for most, frost during their growing season is a real possibility. Think of northern orchard crops, apples or cherries, whose flowers are frozen (and possibly killed) in a late frost. Global warming notwithstanding, it’s not at all uncommon in the Upper Midwest where I’m from to see frost every month of the year. Across the Sun Belt, citrus growers routinely face frost as their crops ripen.

Most plants normally supercool to a few degrees below 32°F, but generally ice nucleators cover plant surfaces—leaves, stems, flowers—and initiate freezing. On clear, windless nights, heat loss into the open skies causes plants and other objects to become colder than the surrounding air. The air temperature may never dip below 32°F, but temperatures of leaves and the soil surface may fall below freezing and ice nucleators initiate freezing (radiation frost).

If moisture is present on a plant surface and there is an entry point (a wound, a broken epidermal hair, or a stomate), ice can form and propagate within the plant’s intercellular spaces. Ice crystals within cells are always lethal. But that’s not how damage is generally caused by frost, and the ability of a plant to adapt to seasonal cold plays no part. Instead, ice in the intercellular spaces causes water to flow out of the neighboring living cells into the intercellular spaces where it too freezes. As the amount of intercellular ice increases, more and more water flows out of cells. Ultimately, dehydration rather than freezing per se injures or kills the plant.

Many woody plants are not much susceptible to this sort of frost damage. Yews and oaks are examples. Research indicates that morphological features such as thick, waxy cuticles act as barriers to ice nucleation and propagation in these plants. In some plants, the propagation of intercellular ice is blocked from entering tender lateral shoots or blossoms. There has been some success on an experimental basis spraying hydrophobic particle films on the surface of tomato plants, which are tender and can be killed by frost, to block ice nucleation. But the current procedure is probably not worthwhile on a commercial basis and impractical for a home garden.

An obvious practical approach a gardener can take is to be sure that plants are well watered before a period of expected frost. Having fully turgid, nonstressed plants may prevent killing cellular dehydration that can accompany a growing-season frost. In the cranberry bogs of New England and Wisconsin, when there is threat of frost, commercial growers continuously apply water to cranberry vines with sprinklers. The rationale behind this is that as water freezes, heat is released. This is what is known as the “latent heat of fusion”, and it is enough to keep the vines from freezing. Citrus growers avoid allowing cool air to pool by keeping air moving with giant fans.

As days grow shorter and nights colder, annual herbaceous plants senesce and die, but perennial plants that are adapted to the temperate and boreal zones enter a period of dormancy and begin to acclimate to the cooler and ultimately freezing temperatures that a month or so earlier might have killed them. Despite 100 years of study, our understanding of how plants perceive low temperatures and respond by regulating gene expression and metabolism is incomplete. This is not too surprising really since cold adaptation is an exceeding complex trait that is controlled by a myriad of genes that in turn are influenced by a myriad of factors, and it is nearly impossible to model adequately.

The concept of “cold adaptation” is implicitly presented as if it were a unique, one-time event. This of course is a grand oversimplification. The climate in winter is no more stable than it is in summer. Winter begins on a particular calendar date, but cold temperatures do not usually conform. There are periods of intense cold, followed by warming trends, followed by intense cold. Plants experience these events and respond to them. In midwinter, a warming trend may induce a plant to partially deacclimate, but the next week the same plant may be subjected to intense cold. To survive, it must reacclimate.

In a purely descriptive simplistic sense, as a woody plant adapts to cold, water is flushed out of the cells to the intercellular spaces, where it freezes, and water further flows out in response to the intercellular ice. The composition of fats and proteins in the increasingly permeable cell membrane changes, and salts, sugars, and proteins are synthesized that are concentrated in the living cells and increase the solute concentration, acting as “antifreeze”. Freezing and killing dehydration do not occur.

The ability to maintain this state, where intercellular water is frozen but the adjacent cells remain viable and intracellular ice nucleation is suppressed at very low temperatures is called “deep supercooling”. What allows small quantities of water within cells to avoid freezing, despite the proximity of extracellular ice and low temperature, is poorly understood. The ability to supercool seems to be related to the cell wall structure and composition, but there are also adaptive features that must be under genetic control.

Over the last two decades, increasingly sophisticated molecular biology techniques have been developed for plants. More and more these tools have been applied to teasing apart the genes and their roles in cold acclimation of the weedy species Arabidopsis, the fruit fly of plants. Lots of progress has been made. But from an anthropomorphized view of evolution, the goals of Arabidopsis are quite different from those of woody temperate plants, and Arabidopsis has the capacity to survive only a few degrees of cooling below freezing. The knowledge gained from Arabidopsis will certainly aid in breeding more frost tolerant plants and crops, but understanding cold adaptation and deep supercooling may remain elusive.