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.

I shall confidently make one prophecy for the coming year: most New Year’s Resolutions will be broken by the time the first flowers of spring burst into bloom.

January takes its name from Janus, the Roman god of door and gate. With his two faces, one facing forward, one looking back, Janus could both view past events and see forward into the future. In 46 BC, when Julius Caesar introduced a new calendar to better reflect the agricultural seasons, the leadoff spot suitably went to Janus. So, if we turn out to be two-faced in both making and breaking our resolutions, we may justifiably cite precedent.

The problem lies not with us. Our self-made promises for the New Year are, in themselves, laudable things. As New Year’s day arrives, why not make a vow to change some aspect of oneself? By all means, let’s face the chill blasts of January with the warm and soothing prospect of an improved self.

No, the problem is a structural one, having to do with resolutions, which come in one of two kinds. There is the abstinence resolution, in which we vow to forswear some bad habit: like drinking, gluttony, and being late for work. The problem with these resolutions is that, once fulfilled, we are where we should have been in the first place; our strenuous resolve has landed us at the norm: an improvement, to be sure, but scarcely thrilling. We have climbed to ground level.

The second kind of resolution is action-oriented. We promise to start exercising, eating better, spending more quality time with the family. Resolutions such as these do not break so much as evaporate. As soon as we pass up the gym in order to catch up on Facebook, take the first bite into a cheeseburger, miss a child’s dance recital due to work, the resolutions—commandments once boldly chiseled onto the tablet of our conscience—dissolve into a pile of psychic rubble.

Taken individually, both kinds of resolutions float separately in a kind of existential void. Worst of all, each leaves us solitary in our pursuit of self-improvement. Who notices when we bend or break a promise made in haste at the New Year’s approach? Indeed, no one is paying much attention, save our consciences—and God, who has seen this sort of self-betrayal many times before.

What New Year’s resolutions need—what we need—is a way to keep faith with ourselves, achieve our goals, have fun, and have something tangible to show for our efforts.

For 2010, I propose a revolution in resolutions. It is in the garden where our dreams of self-betterment can come true. The garden provides a delightful and serene setting where you can live up to your hopes for the year, enjoy the company of your family, and reap a harvest of benefits. Here, your resolutions will literally bear fruit.

In a recent survey, our company, W. Atlee Burpee, asked respondents to cite their top New Year’s resolutions. The seven most frequently cited are getting more exercise, eating more nutritiously, losing weight, saving money, spending more time with the family, reducing stress, helping the environment.

Eureka! The answer is at hand. The best, surest way to fulfill all these resolutions is to be found in the garden. Nothing nebulous about tending to a garden in your own back yard.
Here resolutions grow into delicious vegetables, nutritious salads and serenely beautiful and fragrant flowers.

In your garden you escape the futility of the treadmill, your exercise bringing new pleasures, plucked from the vines and pulled from the soil, and welcome discoveries of floral display. Extraordinary savings grow in the garden as well, as you reap a bumper crop of savings together with a priceless array of flavors. The garden offers a one-of-a-kind opportunity for the family to be creative and productive, and have fun. Think of it as space in the home—or at your community garden—dedicated to addressing all seven resolutions.

America’s thousands of new gardeners are rediscovering a magical realm where—amid the flourishing vegetables, blooms, herbs and fruits—we grow into better people. 2010 is growing to be a great year.

The above appeared in a shorter version in the Op/Ed section of the Atlanta Journal-Constitution on December 29, 2009.

Like a splash of water on the face, as we stare at our future in the mirror, the first of the year revives us. Or that is the illusion, perhaps, reflected in the dim mirror of the winter solstice.

New Year’s resolutions arrive, appropriately enough, when the sun arcs its lowest horizontal path across the northern hemisphere, robbing us of the light of day. Possibilities hang before us in the air, like the next twelve months of our lives. What shall we do when we turn from this mirror?

New garden designs gather in the mind, along with dancing sugar plum fairies. New cultivars bewitch us from their frames in the new plant catalogues. A sense of togetherness grows stronger, in spite of family holidays or, perhaps, hopefully, because of them.

And what about that body underneath the face? Sure could use more stretching, bending, squatting, kneeling and pulling than it had last year. Am I right?

Sandwiched between the ears is a lot of white and an uncertain amount of grey matter. Let us bone up this winter on our plant knowledge and garden methodology. Also, an inventory or even just a meditation on our tactics would help. Tactics are unconscious—“second nature”. Therefore, like the memory palaces of old, running through our spring and summer routines, and anticipating our long-held habits, rarely hurts and always helps. “The toe bone’s connected to the foot bone, the foot bone’s connected to the ankle bone” and so on, all the way up to the “sun bone”. Somewhere in all that are garden bones. It is a good idea to memorize them too.

At Heronswood, we have been hacking away at the new catalogue underbrush. Soon it will arrive, gleaming, on your door step, tossed by St. Fiacre’s newsboy. The rational, sometimes joyful, sometimes onerous work of creating the mouth-watering new cultivars is over. We continue to test shipping container endurance—bang-up and freezing temperatures. Only you will be the final judge.

Want to save money? Grow a vegetable garden in full sun. Want to feel deeply satisfied? Grow a perennial garden, or a series of them here and there throughout your yard, back and front.

Hungering for a sense of togetherness or simply a connection to your neighbors? Join a local garden club. Or haul your family out into the yard and create your own version. Organize a garden block party—it may not be easy at first, but neither is spinning class.

I have said before that air, water and sunlight comprise the greatest show on earth. Moreover, a garden seems to focus the main New Year’s resolutions in one time and place. It is both simple and elegant. Plus, your life will never be the same after taking on a garden.

Gardening beats worldly vices to a pulp. Even some metaphysical vices as well, but in my post catalogue partum depression blues, I cannot recall which ones. Or maybe the garden confers so much a sense of grace and redemption that virtues simply replace the empty spaces the worldly vices left behind. Thank God.

Long live the garden resolution revolution!

In the early seventeenth century, when our immigrant ancestors first settled what would become the USA, they tasted their soil to determine its potential as farmland. This practice persisted well into the twentieth century. A sweet taste told them the soil was neither acidic nor basic but around neutral; a sour taste indicated acidity and a bitter taste alkalinity.

Acidic and basic describe attributes of a chemical property, but soil itself is neither. It is the soil solution, the free water in contact with soil, that makes soil acidic or basic and gives it a characteristic taste. Those old farmers knew that most of their crops would thrive in a sweet-tasting soil. No doubt many were proficient at accessing their soils this way, but today we test a soil’s “pH”.

pH quantifies the degree of acidity of a solution. The concept was introduced by Danish chemist S.P.L. Sørensen in 1909. “H” stands for hydrogen, but no one knows for certain what “p” actually refers to. Effectively, p is a constant and stands for “negative logarithm”, which is how Sørensen defined pH (the negative logarithm of the concentration of hydrogen ions in a solution). Speculation is that p stands for “power” or “Potenz”, the German word meaning power. Others believe it refers to “potential”. In any event, any chemical calculation involving acids or bases will include p.

Sørensen set the pH scale from 0 to 14. A pH value of 7 is neutral (neither acidic nor basic). Values less than 7 are acidic; those greater than 7 are basic. Because the pH scale is logarithmic, a value of 6 is 10 times more acidic than a value of 7; it is 100 times more acidic than a value of 8 (alternatively, a value of 8 is 100 times more basic than a value of 6).

pH is based on the composition of water: hydrogen (H⁺) and hydroxide ions (OH^–); the chemical formula for water is H₂O. Pure water, freshly distilled, is neutral and by definition has equal amounts of H⁺ and OH^–. These ions are attracted to each other by electrostatic charge, and they unite and separate constantly, coming together as water itself and separating as free ions. Stated another way, the different forms of water are in equilibrium with each other, as represented below:

H₂O ↔ OH^– + H⁺.

If acid is added to pure water, the concentration of H⁺ dominates, and the solution is acidic; if base (OH^–) is added, the solution becomes basic. As a reference, battery acid (H₂SO₄) is about pH 1; vinegar is pH 3; human blood is pH 7.2; seawater is pH 8; and drain cleaner (lye, NaOH) is pH 13.3.

Soil is more than a simple repository of minerals, and its characteristics are dramatically influenced by pH. It is composed of variously sized particles, both organic and mineral (inorganic) in origin. The organic portion is derived from products of living organisms or the decomposition of those organisms. Inorganic particles contain no carbon and result from weathering of bedrock. Soil also abounds with life.

Between soil particles is pore space; air and water fill this void. In very fine soils, the pore spaces are very small; in coarser soils, the pore spaces are larger. This is important because pore space determines the degree of air and water conductivity within a soil and affects the ability of soil to retain water and nutrients.

Organic particles come in all different sizes; examples can be found in the thatch layer of a lawn or the debris of a forest floor. A mineral layer lies below this debris; this layer is where most life in the soil occurs and includes most of the organic matter accumulation. It is a layer rich in humus, the smallest of the organic particles.

A boulder could be considered a soil particle, but it is sand, silt, and clay that are the mineral particles vital for plant growth. Sand is the largest (0.1–1 mm in diameter; 25.4 mm per inch) and clay the smallest (≤0.001 mm). Alone, none of them make up an adequate soil, but the three together constitute a “loam”. The ideal garden (or agricultural) soil is a loam composed of roughly equal amounts of sand, silt, and clay. Loams contain more nutrients and humus than sandy soils, have better infiltration and drainage properties than silty soils, and are easier to cultivate than clay soils. They are chemically active and retain water and minerals.

Most plants grow best in soil that is neutral to slightly acidic. At this pH, plant-required minerals (nutrients) are available and microbes convert inorganic nitrogen into plant-usable forms. The essential minerals, by convention, are usually divided into two groups: those needed in relatively large amounts (macronutrients) and those needed in small amounts (micronutrients).

Of the macronutrients, carbon, hydrogen, and oxygen are readily available in air and water. Most soils have enough calcium, iron, and magnesium. But nitrogen, phosphorus, and potassium (not surprisingly, the ingredients in common fertilizer mixtures—called “NPK”) are insufficient in many soils. Also, in more and more soils, there is not enough sulfur. This is largely because of environmental regulations enacted several decades ago that limit sulfur’s release into the atmosphere. The micronutrients (cobalt, manganese, copper, zinc, silicon, molybdenum, boron, aluminum, and chlorine) are needed in tiny amounts only, but if lacking in a soil, acute plant problems result.

These nutrients are available to plants in the form of dissolved mineral salts. Soil particles interact with them, attracting and trapping them. They are metal ions that have positive electrostatic charges, just as hydrogen ions (H⁺) do. Clay and humus, the smallest soil particles, are negatively charged. Because opposite charges attract, in the soil solution under more or less neutral conditions, salts are attracted to and held by clay and humus in a weak chemical bond.

On a molecular scale, these metal ions (for example, Ca²⁺, Mg²⁺, Fe³⁺) are large relative to H⁺. Because of this size difference, H⁺ can displace a metal ion by slipping beneath it and adopting the charge that held it. In a soil that becomes acidic, excess H⁺ displaces the metal ions (the plant nutrients), which are then leached from the soil and lost to the plant.

Under normal growing conditions, plants use H⁺ in just this way to obtain nutrients. Root hairs growing among soil particles secrete H⁺ that causes bound nutrients to be released and to become available for plant absorption. But this process is disrupted at pH extremes.

Basic soils create plant-growth problems too. In many parts of the eastern USA, pin oak (Quercus palustris) is commonly sold in nurseries. It grows well in rich, moist, well-drained, slightly acidic soils but is a poor choice in regions with clay-rich, poorly drained soils. In these soils, pH 7.5 or more is common, and at this pH, iron, which is needed for photosynthesis, is converted to an insoluble form (rust), and the pin oak develops chlorotic (yellow) leaves and eventually dies.

Soils in areas with relatively high rainfall, such as the Northeast, tend to be acidic. Those early immigrants in New England amended their soil, as we do today, with crushed limestone (Ca₂CO₃) to raise its pH; later in Virginia, George Washington and other tobacco farmers used crushed oyster shells from the Chesapeake Bay for the same purpose. This is effective and necessary in many areas.

Soils of the western USA tend to be basic (alkaline). These soils developed over millennia in relatively low rainfall environments from alkaline parent materials (rock). Lowering pH with acid drenches or amending the soil with iron chelates is possible but effective only temporarily. Mulches and working peat, which is quite acidic, into soil will improve soil structure and lower pH somewhat. A good approach for soil of any pH is to use plants adapted to that pH. In the case of the pin oak, American (eastern) sycamore (Platanus occidentalis) or basswood (Tilia americana) do well in basic soils and would substitute well.

Knowing the pH of garden soil is important information, and it should be a prerequisite to fertilization. Fertilizing an acid soil is futile; nutrients are not retained and will merely contaminate neighboring water sources. And this knowledge may well explain apparent nutrient deficiencies or a lack of vitality in certain plants.

Please see our pH and soil test kit here.