Ultra-Local Native Plants

May 5th, 2015

Gardeners trying to be gentler on the environment and kinder to wildlife have jumped on the native-plant bandwagon big-time the last few years.

Native plants are a hot trend lately. But how local do natives need to be?

The message heard is that natives don’t need to be sprayed, they’re low maintenance, hard to kill, best for pollinators and beneficial insects, and just way more all-around “moral” than growing “foreign” or “exotic” plants.

Let me say first thing that I like most native plants in the garden and think it’s a good trend that people are planting more of them.

For feeding pollinators and beneficials, natives particularly shine (some more so than others, as Penn State’s research is showing).

But natives aren’t wonder plants.

They can – and often do – get bugs and disease. Don’t expect perfection.

They still take some care, even if it’s little more than cutting down spent foliage once a year and managing spread (or lack of it).

And yes, native plants can even die or become invasive. As with any plant, you can’t just plant any native anywhere you want and expect it to thrive, survive and perform perfectly.

Part of why it’s not so simple to just switch to natives and thereby solve ecology’s ailments is the matter of what’s a native in the first place.

A lot of lists for native plants label a species “native” if it’s known to grow naturally anywhere in the United States.

Right off the bat, that’s a problem because this country is so big and has so many differing growing conditions that the term “U.S. native” is almost meaningless.

Good luck growing an Alaska-native heartleaf arnica or a Florida-native palmetto palm in your back yard.

If your goal is a plant that’ll thrive under minimal care, you’d have better luck with plants native to, say, Germany, parts of Korea or China, and other regions with similar climates.

Part of the problem with assigning native status is that maps are artificial boundaries… changing with time and decided by people.

That always makes me wonder what we’d do if, for example, the French had never sold Jefferson the Louisiana Territory. Instead of purple coneflowers being considered a native perennial, would we consider this Midwest prairie species to be a French exotic?

Or what if the South had won the Civil War? Would our much-touted “native” oakleaf hydrangea be considered a foreign exotic?

That leads to the question of how local a plant has to be before it’s a meaningful native, one that’s truly adapted to our climate and soil and one useful to our local pollinators, birds, butterflies and such.

Is the mid-Atlantic region close enough? Or should we zero in just on plants native to Pennsylvania’s boundaries? Or should we narrow it down even more than that?

The logical answer is, the closer the better.

But is it even possible to figure out what was growing in the immediate area when the Europeans first colonized here? (Picking that time frame also is arbitrary, by the way, since plant colonies creep, change and disappear over the centuries.)

That’s what Cumberland County Master Gardener Susan Skender decided to find out.

Susan is a proponent of an up-and-coming style called “naturalistic planting,” which involves blending native and non-native plants in intermingled swoops that mimic nature.

An example of a naturalistic design using native plants, by Pennsylvania designer Larry Weaner.

It’s a sort of peaceful middle ground in the conflict over natives vs. traditional green-meatball landscaping. (Read more about naturalistic planting in my Pennlive/Patriot-News garden column.)

Like most gardeners, Susan loves plants and doesn’t want to get into checking passports to determine what’s allowed in her yard.

On the other hand, she recognizes the value of natives and wants to use those, too, for their ecological benefits.

So for the recommended 50 percent of non-natives in a naturalistic garden, she turns to plants adapted to climates as much like our own as possible.

For the 50 percent native plantings, she tries to keep them as local as possible.

That’s what led her to check and cross-check every plant-origin source she could find to come up with incredibly meticulous lists of plants that are native to each of six counties surrounding Harrisburg – Adams, Cumberland, Dauphin, Franklin, Perry and York.

“After collecting a massive number of plants, I compared them to the plants that Allan Armitage (noted author and researcher) felt were garden-worthy,” Susan says. “I was not looking for restoration plants. I wanted something that the normal, every-day gardener would find attractive in the backyard.”

Susan has shared her list with Master Gardeners and other local plant geeks. I saw her work recently and was astounded at the detail and usefulness of what she found.

You’ll be surprised, too.

Fothergilla is usually listed as a “native plant,” but it’s not native to Pennsylvania.

For example, witch alder (Fothergilla) is almost always listed as a native shrub. But it’s native to the southeastern United States and not Pennsylvania at all.

Summersweet (Clethra alnifolia) is another commonly listed native shrub that’s native to eastern Pennsylvania but apparently not to any of our six central-Pennsylvania counties.

And if you really want to get picky, scarlet bee balm (Monarda didyma) is native to Cumberland, Dauphin, Franklin and Perry counties but not to Adams and York.

Susan agreed to share her list here, so for your native-plant-perusing pleasure, you’ll find her lists under “Ultra-Local Native Plants of South Central Pennsylvania” in the George’s Favorite Stuff section of this website.

The lists spell out which counties each plant is native to, and asterisks indicate which plants Allan Armitage considers to be garden-worthy.

Susan used such online plant resources as the U.S. Department of Agriculture, the University of Pennsylvania’s Morris Arboretum, the Pennsylvania Natural Heritage Program, Manada Conservancy, and Bowman’s Hill Wildflower Preserve as well as Ann Fowler Rhoads and Timothy A. Block’s “The Plants of Pennsylvania” encyclopedia, Allan Armitage’s “Native Plants for North American Gardens” and numerous catalogs of native plant growers.