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Gardening in the Lower Midwest

A Practical Guide for the New Zones 5 and 6

Indiana University Press

First Lessons

Many gardening books begin with sections on soil and how to improve it — and presumably oneself — by engaging in a little garden task called double-digging. Mine begins with gardeners, improved or not.

You can be a card-carrying gardener without once double-digging a border. Indeed, a fair portion of a gardener's education is derived from trying to avoid such wrenching work, on the premise that minds may last longer than bodies. Which is not to say that you blithely ignore a time-honored and, I concede, occasionally useful skill. It's just that not all known skills — or plants — have to find a use in your garden.

Some of the skills you need to navigate the modern and determinedly sophisticated world of gardening revolve around making informed decisions, and I don't merely mean which European market lettuce to sow or which roomy pair of mail-order trousers to order.

You learn these gardening lessons as you progress in the classic evolution from an interest in growing a few vegetables and annual flowers to a gradual appreciation and greed for every perennial known to horticulture. This enthusiasm, in many instances kept from excess only by the fortunate circumstance of shallow pockets, is succeeded by arrival at a higher plateau of awareness of the role of the more subtle foliage plants, including trees and shrubs, until, finally, there you are, right back at a new appreciation for the vigor and honesty of annuals, with the cycle beginning again and each time deepening the gardener's aesthetic and horticultural skills.

Along the way you have struggled to understand the difference between annuals and perennials, broadleaf and needled evergreens, determinate and indeterminate tomatoes, grafts versus plants grown on their own roots. You have picked up on the grand peculiarities of biennial flowers, suffered your share of mail-order mistakes, and learned that there is more to houseplants than dracaena and African violets.

But there are harder lessons than these — bigger lessons, smaller lessons; lessons seldom mentioned, much less taught.

Lesson 1: Nothing Is Simple

Consider hardiness zones. Nothing could sound simpler. Here they are, neatly colored guidelines, rules — almost laws — about what you can grow where you live.

That's why the redrawn plant hardiness zone map published in 1990 by the U.S. Department of Agriculture may have shaken up a few gardeners. Even if your yard landed in the same number zone as before, the basis for the zones shifted a bit.

The USDA map replaces one drawn twenty-five years earlier and confirms what common sense has told us. Cities tend to be hot spots in their zones, mountains tend to be cold. However, the new map does not support the greenhouse effect or global warming theory and instead tells us that overall, notably in the Southeast, winters are a bit cooler than they were in the 1960s. The cold zones are advancing slightly in Kentucky, Illinois, Missouri, Ohio, and Michigan. States with weather or winter temperatures similar to those on the 1965 map include Iowa, Kansas, Nebraska, and Wisconsin.

There now are three hardiness zone maps to consult. That is because there are three versions of hardiness reality. (I know, you hoped there was only One Big Truth in gardening — the last bastion of honor and optimism that crosses all cultural, social, financial, and racial lines.) Although the USDA map is the most widely published, frequently reproduced in mail-order catalogs and gardening books, you should at least be aware of two others. The AA map, produced by the Arnold Arboretum in Massachusetts years ago, is used in the indispensable Wyman's Gardening Encyclopedia, reprinted by Macmillan in 1986. The Rutgers University map, developed by the school's Cook College in 1990, is seldom seen. (The U.S. Forest Service produces its own specialized zone maps, but we can ignore these.)

The USDA map has eleven zones. It marks Zone 6 as having annual lows of –10 to 0 degrees and Zone 5 as having annual lows of –20 to –10. The AA map with nine zones marks a slightly different Zone 6 with a –5 to 5 range and the area just north of that a Zone 5 with –10 to –5. This puts northern Indiana in its Zone 4 with –20 to –10 range, or the Zone 5 range of the USDA map. The Rutgers map has twenty-three zones, and its makers compiled their zones based on a lot more than minimum air temperatures. They also factored in maximum air temperatures, precipitation, wind, sunshine, humidity, elevation, and length of growing season. Gardeners know these things make a big difference. It's often not the winter cold that kills, it's the rain that rots. It's not the heat, it's the desiccating winds. The Rutgers map, therefore, is perhaps the most accurate of the three. But accuracy is not the issue. The one to favor is the USDA map, simply because it is the one used by a majority of the folks who sell us plants.

This will horrify those who dole out microscopic carrot and beet seeds one by one in a furrow or who insist on engineered edges to the lawn and shrubbery, but the truth is that you should consult any zone map as a generalization only. In fact, you can garden without ever consulting a hardiness zone map of any description. Rely instead on local knowledge. That means buying from regional nurseries, which normally won't carry plants that are not 100 percent survivors in their area and yet may indulge in variety past forsythia, maple trees, Day-Glow orange roses, and Stella de Oro daylilies. It also means close observation of good gardens in your neighborhood. To be very clear about this, it means avoiding national discount stores that mount instant garden centers from March through June, staffed generally by workers chosen for the ability to lose plant labels and swear that everything they sell will thrive in your region.

Or you can play the game more dangerously, using hardiness zones as challenges rather than rules. Washington Post garden writer Henry Mitchell once commented on a widespread trait among gardeners — the desire to garden one or preferably two hardiness zones south of where they reside. The Upper Midwest gardener, for instance, longs to grow too-tender American pillar rambling roses, he said, while the Bostonian covets magnolias and evergreen hollies and the Tidewater Virginia matron looks at her boxwoods and yearns for oleander.

Which brings us to microclimates, one of the proofs that Mother Nature doesn't read hardiness zone maps.

A microclimate is a nook where conditions are different from those in the rest of the garden. There can be microclimates on both sides of what passes for normal in the Zombie Zones. Of course, we seldom hunt for the chill, exposed spot, searching instead for an area beside a wall or hedge or in the ell of a house addition that protects from wind and cold and tends to augment warmth, allowing us to grow spring-blooming jasmine where we should not be able to.

Practically speaking, a useful microclimate is a space where you can grow tender plants, like that jasmine, but it also can be any spot with a peculiar set of circumstances. Wind baffles occur beside walls, hedges, solid fences, earth berms, slopes, hills, retaining walls, houses, or woodpiles. Boggy spots can be found near gutter downspouts or around an outdoor water faucet. I have a rather nice one that is boggy only in the growing season and not in winter, when many plants can't handle wet feet. It's where I toss out dog water and refill dog water dishes in the summer. Desert conditions can be found under a deep roof overhang on the south or west side, in planters, next to foundations, on the tops of hills. Extra warmth often occurs near heated buildings where radiant heat loss can add up to as much as one hardiness zone or ten degrees' difference. Even insulated houses tend to heat the outdoors a bit. You might as well take advantage of it.

To find your microclimates, stroll about and note where you are warmest in a winter wind, coolest in a summer heat wave. You can follow the cats around in early spring, too. They invariably locate a late-winter sunning spot in the heart of a microclimate. If you insist on being technical, buy two high-low thermometers and set one at plant height for a week in the suspect microclimate, the other in a less protected area, and compare notes each day.

Lesson 2: Sooner or Later You Will Speak Latin

You shouldn't call a pelargonium a geranium, but of course we all do. This is one of the more famous instances of the verbal confusion that reigns as gardeners mix common names with proper Latin names. The boldly colored, large-flowering annual plant we call geranium is really a pelargonium, "geranium" being the proper Latin name for a low-growing, pastel-flowered perennial ground cover also known as cranesbill.

A small understanding of Latin names will wow your relatives, cow inexperienced gardeners, and put garden center clerks on notice that you are not to be trifled with. Hook up with the Latin system and you open the door to a vast and orderly world of plant nuts past and present. It is especially helpful in catalog reading; once a workable familiarity is acquired, you can be free of the bondage of color-photo catalogs with their invariably higher prices and/or lower range of offerings. There really are gardeners who thrive on single-spaced plant lists with the only English appearing as the price in dollars and cents.

You can acquire this knowledge painlessly, if slowly, by simply keeping an open mind and being willing to write the proper Latin name on your orders, your labels, and your planning sheets.

When you come across Acer palmatum 'Dissectum', make yourself read rather than pass over the Latin for a maple (Acer) with finely cut ('Dissectum') leaves shaped like a hand (palmatum). It's not as bad as being raised on U.S. measures and learning to cook in metric, but self-taught Latin nomenclature can be sticky going at first.

Blame Swedish naturalist Carl Linnaeus. He made it his life's work about three hundred years ago to give systematic Latin names to all the plants he knew — some 7,700 species — and to classify them according to their sexual features. He was the first to classify in this manner. Eventually scientists all over the world adopted his standard of a two-name naming system, and it is continued today. This two-name system is similar to the way we file human names last name first — Heilenman, Diane — in order to show the relationship of the individual to a larger family.

Clearly, Itea virginica and Itea ilicifolia are related. The first, as you probably figured out, is a native of the southeastern U.S. Its common names are sweetspire, Virginia willow, and tassel-white. The second itea is from western China and is more mysteriously identified as having glossy leaves (folia) like ilex (ilici-), which is holly. This itea does not have a common name that I know of. One itea is not like another. Itea virginica is hardy in Zone 6 and is valuable because it grows in sun or shade and in almost any kind of soil. Its Chinese cousin is of no account to us midwesterners; it's hardy only in warmer Zone 7.

Let's take ilex for our next example. We know this wonderful family of mostly evergreen trees and shrubs as holly. Again, not all ilex are equal, as those of us who have lived through winter dieback and kill-off know all too well. There's a big difference between Ilex aquifolium, known as English or European or, sometimes, Oregon holly, which can grow along the shores of Lake Michigan and in the moist air of the West Coast but is not happy elsewhere in Zone 6 and certainly not in Zone 5, and Ilex opaca, known as American holly, a hardy fellow that will thrive in Zone 6 and often in Zone 5. Ilex crenata, the Japanese or box-leaved holly, is a zones 5-9 plant that can suffer winter browning if subjected to harsh winds. Some ilex jewels for midwesterners are our underused deciduous and evergreen native holly shrubs, including I. decidua, I. glabra, and I. verticillata.

The alert reader may have noticed that my first example — Acer palmatum 'Dissectum'— in fact had three, not two, Latin names. The first is the genus name. The second, never capitalized, is the specific or species name. If there is a third name — which, by the way, can be either Latin, Latinized, or English, and which is not italicized but instead set off by single quotation marks — it indicates the variety or form. This last is a descriptive word, almost an adjective, that refers to a distinguishing trait or an important person connected with the discovery or dissemination of that plant. The variety name can be crucial in determining if a plant is hardy in a particular zone, or has some special characteristic that is desirable to a particular gardener. For instance, one form of the tender Ilex cornuta (Chinese holly) is 'Burfordii', which some folks in Zone 6 may get away with growing. But if they simply orderIlex cornuta without specifying 'Burfordii', they don't have a prayer.

Juniperus chinensis 'Sargentii' is a juniper from China named after the man, Sargent, who discovered it. Juniperus horizontalis 'Douglasii', sometimes called the Waukegan juniper, is a low-growing juniper named after the nursery in Waukegan, Illinois, that discovered it. However, it is not the only juniper with a prostrate or horizontal growth habit. There is, for instance, J. h. 'Blue Rug'. All of these plants are the same species, but the varieties differ sufficiently to warrant having names of their own.

And then — if you're still not sold on the idea of using Latin rather than common names — there's the matter of laurels. Oregon's Forestfarm Nursery, which produces one of my favorite no-pictures mail-order catalogs, alerts us to nineteen plants called laurel that actually range through genera including kalmia, magnolia, rhododendron, and arbutus as well as laurus. To say it doesn't matter is like thinking all women named Diane are related. Obviously, knowing a little Latin is helpful if you want to get what you ask for.

At the beginning, the game plan is to try to absorb rather than study this minefield of Latin terms. Don't be afraid to be ignorant. When you run across a plant you love, get the proper full Latin name and write it down. I keep these scraps in my schedule book, in my wallet, on the car dashboard, and in my pockets. I also lose them with great regularity, but it's amazing how much you retain by the act of writing.

Eventually you get to the point where you know a lot of names without looking and will think of firs as abies and willows as salix, or even geraniums as pelargoniums.

But remember, Nothing is simple.

Sometimes they change the Latin names on you. The genus Funkia became Hosta in my grandmother's era, and in mine the species datura became brugmansia; many of the plants we grew up knowing as chrysanthemum have been sent to live with other existing genera such as ajania, dendranthema, and nipponanthemum. The botanists do this for important reasons that really have nothing to do with keeping us gardeners in our place — because of revelations along genetic lines or because a conflict of names has appeared.

That is why we have reference books.

The bible is Hortus Third, a dictionary and description of plants cultivated in the United States and Canada, compiled by Liberty Hyde Bailey and Ethel Zoe Bailey and revised and expanded by the staff of the Liberty Hyde Bailey Hortorium of Cornell University. It is big and heavy and expensive, over $100, but it is sometimes offered as a loss leader item by garden book clubs. Look for this and buy it then. The other, much smaller book is Dictionary of Plant Names by Allen J. Coombes, from Timber Press. It cross-references plants by common name and Latin name. It includes pronunciation guides and limited explanations of the names, and it's small enough to carry to the nursery in order to double-check names prior to purchase.

When it comes to pronunciation of Latin names, here is a secret known to art historians, teachers, and newscasters. Say it fluidly and with confidence. Don't falter, stumble, change your mind, or apologize. Fully two-thirds of the audience won't know or care if you are correct, and of the other one-third, I'd bet that a good majority will think they've been mispronouncing it all this time.

Still, it never hurts to look up the proper pronunciation; but if you are caught in field circumstances, here are a few tips to help keep your tongue straight: C and g are hard, as in "cat" and "gate," except when followed by e, i, y, ae, or oe. Examples: catalpa, gladiolus; but acer, A-sir; gynandra, ji-NAN-dra.

A double vowel, such as ii, is generally pronounced with two syllables. Wiltonii is Wil-TON-ee-aye.

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Excerpted from Gardening in the Lower Midwest by Diane Heilenman. Copyright © 1994 Diane Heilenman. Excerpted by permission of Indiana University Press.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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