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Native plant design: starting points

Introduction

A garden is by definition artificial. We compress and sometimes distort nature to create a landscape for any number of purposes, but most often for visual pleasure and amusement. And after that, it widens into an astonishing array of personal expressions, ranging from a small decoration near the front door of the home to vast estates employing legions of maintenance staff.

In traditional landscaping, an organized approach begins with a site analysis, a review of owner interests, needs and preferences, definitions of activity areas, and from this is drawn a plant selection list to meet practical and artistic support of dwellings and secondary structures. The dizzying array of plant options developed by nurseries gives a designer a wide palette to use for visual impact. About the only limitation is the size of purse and exuberance of children and the family dog.

It seems that native plants are becoming trendy because climate issues have begun to stir a certain anxiety or at least unease. Perhaps, if we accommodate the natives, we might forestall some widespread extinctions, including our own.

Websites and native plant sales are popping up like invasive weeds, particularly from groups with environmental agendas: a good thing if only to introduce us to an interesting group of plants often overlooked in landscape design.

Important consideration of terms

Wildflower is not synonymous with native. There are many species, ranging from invasives that snuck in to the continent from other parts of the world to landscape plants that have escaped cultivation, which are considered "wildflowers." It's only there because it grows by itself in the wild, and includes some our most beloved (and cursed) weeds.

A native plant is a species indigenous to a specific locale. It evolved, adapted, and flourishes in a specific habitat and that's always where it will be happiest. Some species have very wide ranges, such as the entire eastern half of the United States, while others are highly specific and might be found only in isolated pockets as narrow as a single county.

If we understand the specific habitat on which is parked our dwelling and potting shed, a hefty plant list ideal for that specific location can be easily constructed. Of the thousands of plants native to Pennsylvania, about 1,400 native to the county perhaps 200 or so to the upland forest in which Pennystone Gardens is located. Two miles south or east and five miles west, the habitat is much different, but even a half mile distant, an altogether different set of plants will flourish -- and none of ours would thrive.

Very often stock sold at native plant outlets is fairly wide range, but sometimes also specific to swamps or at least sunny moist areas. The latter are spectacular species and tantalizing to shoppers, but even the most experienced of us will struggle to keep them alive in a less-than-ideal habitat such as an upland forest.

The first step in developing a landscape plan, then, would be to define the precise habitat one has, with particular attention to these factors:

• Light - full sun, part sun, part shade, open shade, deep shade
• Moisture - wetland, swamp, mesic, dry, arid
• Soil acidity - very acid, acid, mildly acidic, neutral, alkaline
• Soil composition - the ratio of sand, silt, clay and organic matter, as well as the presence and type of gravels and small rocks
• General climate - USDA zone, annual precipitation, precipitation averages

Organizing a list

The easiest way for us to tackle plant lists is to first cast a wide net and assemble a list of natives to a general geographic area; the finer the line drawn, the more effective this list will be.

Initial resources can include environmental agencies and groups, state and national parks, localized reference books such as plant identification guides, botanical and native plant societies, horticultural societies, sophisticated garden centers, and possibly botanical departments at local colleges and universities.

Residents of Pennsylvania can benefit from a massive database assembled by Morris Arboretum/University of Pennsylvania. Although designed to search for a specific species, it can also list all the species for an entire county or generalized habitat, and shows a distribution map to give readers a sense of range.

Those elsewhere who are working with a growing list of plants can consult a similar database run by USDA, which shows state distribution maps, but also county maps as applicable.

National Resource Conservation Service, a division of USDA, offers soil mapping and soil composition reports. Although highly technical and a bit daunting for the neophyte, the patient investigator will obtain very useful information to aid in an evolving plant list.

This detective work commences with common names, expand rapidly to an almost overwhelming list of Latin name, then begin to thin down as specific ecological factors trim it to a set of species that will likely do very well in the individual landscape.

Websites everywhere describe many species of plants, easily found on searches for the Latin names. These sites often present images and at least elemental data on growth habits, details on habitat, cultivation counsel, and propagation information. As we take note of what blooms when, how tall or bushy things grow, and organize groups of plants into background, edges, and areas that rapid spreaders can ooze into and the species list will take good form.

However, we can't necessarily buy everything on the list. Native plants aren't stock and trade at big-box discount stores, and most garden centers carry very few. Seeds are more readily available, but sometimes carry their own issues of management. Fortunate gardeners live within proximity of native plant sales, often sponsored by conservation organizations or native plant societies. However, these annual sales will generally include only the easiest-to-propagate/grow and species for a range of habitats. It's easy to get caught up in the excitement of such an event, always a worthy cause, and whisper to ourself that even though it's a plant for sunny, moist ground, that spot near the big tree on the hill could be watered... and so the disappointment will begin.

Most of these sales publish lists before the event, which allows the landscaper to plan. Often the same plants as were offered last year will be repeated again.

Casually mentioned in books published 50 years ago and more were instructions on how to collect plants from the wild, including state and national parks. That's an outlawed practice now, at a minimum frowned upon on ethical grounds. If, however, we're acquainted with a property owner who has a specimen of interest growing wild on their land, and if we have permission, and if we've done our homework and know what they are doing, then we participate in "plant sharing", something done all the time among friends, and a practice that can be helpful because you can see the exact conditions a species enjoys. Sometimes we find a bit of adventure in this process, especially when a stand of natives is doomed because of land development. Then we embark on a rescue mission. What adds to the excitement is that it's often short notice and involves transplanting species that aren't enthusiastic partners into habitats that may not be perfect. The more difficult the species, the harder it is and the more likely outcome may be poor. But with each such effort, we learn a bit more.

A positive note

Specimens found at native plant outlets are concentrated there for a simple reason of economics: they are easy to propagate and grow. This eliminates many that are extraordinarily fussy and would exasperate all but the most masochistic gardener. A collection comprised of these specimens will spread easily and probably be healthy and attractive within the local range of habitat. These are the "good doers," the ones that assure us of success and encourage us to expand our horizons. We find it better to develop masses of pliable specimens than to struggle with a few that give us discouragement.

Because the first order of business for a native plant is to reproduce and colonize an area, selections appropriate to local conditions gradually reward us with dense, lush growth. Beds that begin as mostly mulch with a few plants here and there, within a few years are packed tight with varied textures and shapes. Masses of a few species plants give a garden much greater visual impact than an array of many varied species strung out like a museum botanical exhibit. It's also correct from an ecological standpoint; forest and field are not typically broad in variety of plants in any given location. Plants in the wild cover vast swaths of real estate, and by replicating the feel of it, our landscape gets a more natural look.

Many native plants have limited landscape value. The business of a species, after all, is not to entertain us with glamour, but to continue its kind on the planet, and many of them are not very attractive even if they do play a role in the overall balance of nature. Others are intriguing for varied reasons; insignificant flowers are perhaps followed by curious seed pods (e.g., Anemone virginiana) or a byproduct of astonishing foliage (e.g., Podophyllum peltatum).

Our home garden may also be influenced by the surrounding properties. Reports from time to time discuss projects of those who have "gone native" with enthusiasm and eliminated lawns in favor of wildflower meadows - only to incur the wrath of surrounding homeowners and the local zoning officials. The solution is for us to present natives in the same fashion as other ornamentals, tastefully enhancing the property and never blocking the view of the front door from the street. Suburban backyards that are not fenced are also subject to similar scrutiny, and keeping the neighborhood peace mandates good citizenship in gardening. Natives can be grown, but in a more well-groomed manner. What is one gardener's meadow is another's weed field. An alternative is to relocate to a property where bucolic exuberance is encouraged, i.e., in a rural or semi-rural setting, where a little acreage may or may not be considered a garden.

Larger landscapes, in excess of an acre or two, sometimes raise eyebrows when described as a garden. More often, they are wildscapes, and the chaos of natural habitats is allowed to run unfettered. The expression "garden" is a vague one, to the advantage of many.

Those of us who are purists -- cultivating natives to a specific habitat and nothing else -- will find the path a bit more challenging but not impossible. They will almost certainly get deep into propagation, if only because some options may be limited to seed. Those at the more conventional end of the spectrum, who incorporate natives with introduced species, will find natives to be a useful addition to the landscaping palette, especially shade gardeners.

Native plant gardening is not an all-or-nothing proposition, but there are some obvious limits. Hybrid tea roses and Asclepias syriaca aren't really companion plants, but Mertensia virginica is an ideal early bloomer for the spaces between hostas because it goes dormant at about the time the hostas really leaf out.

Natives can serve as problem solvers, especially in shade gardens. Mitella diphylla, Tiarella cordifolia, Asarum canadense are all exceptionally well-behaved low shade plants that can accent front edges of beds with pleasing textures, while Clethra alnifolia, Calycanthus floridus, Hamamelis virginica and the various native vacciniums and viburnums can dramatically fluff up the understory in landscapes of any size.

At the opposite end of the spectrum, we discover that a lush representation of pure nature doesn't necessarily have to ban some favorites. Pennystone includes hybrid azaleas, a hosta garden, and some pre-existing non-native trees (a Japanese maple, for example), not because they are aesthetically correct but because we simply like them.

Our garden is, after all, our garden, and we define the rules.

But sometimes the challenge is to work within a theme and habitat can define that theme and you can expand from there. To illustrate how one can go from very strict to very relaxed themes, Pennystone Gardens is:

1. A dry, acidic upland forest on a chestnut oak ridge, or...
2. Located in Monroe County, Pennsylvania (northeastern part of the state, zone 5B), which offers more than 1,400 species of native plants for many habitats, or...
3. Located in Pennsylvania, which offers an even wider range of plant species. It sounds odd, but in nature you'd never find Actaea racemosa and Actaea americana, both marvelous shade plants, growing together. The latter is from southwestern Pennsylvania and definitely out of bounds in Monroe County, or...
4. A shade garden, and with many laurel on the grounds is well suited for azaleas, rhododendrons, and hostas

These examples of self-imposed restrictions require a conscious decision on the part of the gardener, but it is left to the reader's inclinations and interests to find a comfort point and overall design strategy. Gardens are individual expressions, and self-satisfaction is the primary guiding rule.