Alternative Lifestyles: Planting with Nature in Mind

By: John Peter Thompson, Chairman, Behnke Nurseries; for more information on invasive species and sustainable, conservation landscaping go to his web log, INVASIVE NOTES 

For many gardeners, the term “invasive plant” spreads terror and discord, creating waves of anxiety and resentment. Currently, invasive plants are defined to be non-native, exotic aliens which reproduce furiously, replacing native plant species and complex self-sustaining ecosystems with, in some cases, biological deserts or monocultures.

The same qualities that make these plants invasive–they reproduce freely, grow voraciously and are virtually indestructible–ensure that they will become champion garden-trade species.

One way to think of invasive species is to think of all the weeds we do not want in our own gardens. The worst ones are those that creep in from our neighbors’ untended yards. Think “running bamboo,” and understand the feelings of those who are tasked with protecting natural areas. They are gardening with a “native-only” concept, and we are gardening with the “anything goes” model. This situation makes for uneasy neighbors, and opportunities for stress and discord.

Not all invasive species were introduced by gardeners or garden centers. Many simply hitched a ride on the bottom of a boot or in the cargo hold of a transport ship; even in the crates of packing materials we use to ship our consumer goods. But some, like kudzu, were originally introduced by the horticulture industry (1876), even though it took federal help to establish kudzu in our southern landscapes. Callery pear hybrids abound in the mid-Atlantic region as a highly recognizable invasive species, and are still recommended by local government agencies (Prince George’s County tree) as a street tree choice, even though the tree is almost always a bad long term landscaping solution.

When choosing plants for your garden, you should know the needs of each plant you select. Does it need light or shade; what are the optimum soil types; how wet or dry is best for your species; and what are the potential impacts on your immediate and regional ecosystem? Using native alternatives to invasive plants reduces the environmental impact and allows you to concentrate on the right plant in the right place.

What are some of the bad actors and what can we replace them with? Lythrum, or purple loosestrife, is a spike-flowered invasive perennial which can be replaced in the garden by Liatris spicata (also known as gay feather or blazing star), an excellent native alternative. Liatris is easily grown in average, medium-wet, well-drained soils in full sun. Once established, liatris tolerates poor soils, drought, summer heat and humidity, but is intolerant of wet soils in winter. The two foot tall clump-forming perennial has long spikes of rounded, fluffy, deep purple flower heads, appearing atop rigid, erect, leafy flower stalks.

If you are seeking a long summer bloomer to match the floral display of lythrum, try hybrid hibiscus such as ‘Lord Baltimore.’ Huge flowers, reliably perennial and fast growing, this plant will fill the summer and fall garden with knock-your-socks-off beauty until frost. Although they prefer wet soils, I have seen them tolerate some fairly dry conditions. And since they grow so fast, they can out-compete many pests, such as another invasive species, the Japanese beetle.

Another bad actor is English ivy. Drive through Rock Creek Park in Washington, DC (or the grounds of my house, and probably your house, too), and the evergreen vine which is pulling off branches of the shade trees is Hedera helix. It is tough to beat English ivy for an all-purpose, practical, indestructible, inexpensive and easy-to-grow ground cover. You do not need to weed it, feed it, water it, mow it, trim it or think about it until it pulls down a major shade tree or your gutter system to your house.

A terrific alternative is Pachysandra procumbens, or Allegheny spurge. This plant is native to the eastern United States and is not to be confused with the evergreen pachysandra you are used to seeing everywhere; that one is not native, and shows up on some “good plants gone bad” lists. Allegheny spurge is best in rich, moist soils and grows to around 12 inches high. It will grow in shade to part shade. In mild winters it may be partially evergreen.

Another great native alternative, Polystichum acrostichoides, Christmas fern, grows in the natural areas of the mid-Atlantic. An absolutely wonderful, shade loving, no-maintenance plant, it has the additional feature of being evergreen. It thrives under trees, and can often be seen in quite dry conditions. Planted en masse, this 24 inch tall species is a workhorse of the shade garden.

An added bonus is that the Eastern white-tailed deer, with its voracious appetite and very bad manners, will eat almost anything else before the Christmas fern. In fact I have a rule which states that deer eat five hundred dollar exotics first, followed by many rare and endangered natives second, and then pretty much everything else. The Christmas fern manages to find a way off of the dinner menu and thus is a perfect choice for a native, natural, and non-controversial landscape solution.

There are other Maryland natives which are easily found in nurseries and can be used as groundcovers, including Tiarella cordifolia, or foam flower, with white flowers and a preference for moist shade locations. Another is Phlox stolonifera, or woodland phlox, in pinks, blues, and whites, which rise to 8 inches tall when in bloom in April.

As a rule, vines are troublesome. Their rambling nature predisposes them to invasiveness. A list of vines which have gotten loose in natural areas is a list of the naturalists’ most abhorred. Consider porcelain berry, Japanese and Chinese wisterias, Asiatic bittersweet, Japanese or Hall’s honeysuckle: these plants terrorize natural areas and native ecosystems. But all is not lost, for there are many well behaved native alternatives such as Wisteria frutescens, or American wisteria, which produces a gentler, not-so-over-the-top inflorescence and a willingness to live with its neighbors, gently draping itself across lateral tree branches.

If you don’t mind dealing with its aggressive tendencies, then the native trumpet vine, Campsis radicans, is for you. Although aggressive to the point of being rampant, it provides brilliantly colored flowers which serve to attract hummingbirds. The orange, yellow or red flowers are true show stoppers.

Tiarella cordifolia

Another great native alternative, Polystichum acrostichoides, Christmas fern, grows in the natural areas of the mid-Atlantic. An absolutely wonderful, shade loving, no-maintenance plant, it has the additional feature of being evergreen. It thrives under trees, and can often be seen in quite dry conditions. Planted en masse, this 24 inch tall species is a workhorse of the shade garden.

An added bonus is that the Eastern white-tailed deer, with its voracious appetite and very bad manners, will eat almost anything else before the Christmas fern. In fact I have a rule which states that deer eat five hundred dollar exotics first, followed by many rare and endangered natives second, and then pretty much everything else. The Christmas fern manages to find a way off of the dinner menu and thus is a perfect choice for a native, natural, and non-controversial landscape solution.

There are other Maryland natives which are easily found in nurseries and can be used as groundcovers, including Tiarella cordifolia, or foam flower, with white flowers and a preference for moist shade locations. Another is Phlox stolonifera, or woodland phlox, in pinks, blues, and whites, which rise to 8 inches tall when in bloom in April.

As a rule, vines are troublesome. Their rambling nature predisposes them to invasiveness. A list of vines which have gotten loose in natural areas is a list of the naturalists’ most abhorred. Consider porcelain berry, Japanese and Chinese wisterias, Asiatic bittersweet, Japanese or Hall’s honeysuckle: these plants terrorize natural areas and native ecosystems. But all is not lost, for there are many well behaved native alternatives such as Wisteria frutescens, or American wisteria, which produces a gentler, not-so-over-the-top inflorescence and a willingness to live with its neighbors, gently draping itself across lateral tree branches.

If you don’t mind dealing with its aggressive tendencies, then the native trumpet vine, Campsis radicans, is for you. Although aggressive to the point of being rampant, it provides brilliantly colored flowers which serve to attract hummingbirds. The orange, yellow or red flowers are true show stoppers.

by Melodie Likel, Perennial Plant Specialist

Schizachyrium

As winter approaches the perennial garden’s vibrant hues fade and turn to shades of tan and brown. In the warm days of Indian summer the job of cutting back the summer bloomers can begin. As these become tired and worn looking each may be cut to the ground to let the fall bloomers shine. After two or three killing frosts have extinguished the bold colors of autumn, the job of tidying the beds for winter begins in earnest.

Andropogon

First, select the plants that will be left standing for interest through the winter. These may include ornamental grasses whose resilient stems will rustle in the winter winds and spring back amazingly even after being weighted down with snow or ice. Rusty brown flower stems of tall sedums stand proudly in the winter garden.

Leaving the dry seedheads of black-eyed susans and purple coneflowers will provide winter food for yellow and purple finches as well as slate gray juncos. On a frosty morning, these bright seed-eaters are lovely to see as they flit and alight on the stiff flower stems.

The bone white branches of Russian sage reach skyward waiting for the return of spring. Cut these back in spring after tiny new leaves can be seen, cut back to within 2-3 inches of the ground. This leaves a bit of stem that will be visible to locate the plants in spring when clearing leaves, removing mulch and fertilizing.

Generally garden debris can be added to the compost pile to enrich gardens to come. If however, the plant was in some way diseased or infested with insects it may be best to dispose of the dead material with your regular trash. Discarding this material reduces the possibility of repeat infections the following season. Foliage of irises especially should be removed from the garden to prevent borer infestations.

Many perennials form a rosette of leaves that lies nearly flat on the ground. The upright, flowering stems should be cut down leaving this basal rosette of foliage, which often will remain green all winter.

Panicum virgatum 'Heavy Metal'

Many perennials are actually evergreen or partially evergreen and should be left standing in the winter garden. Candytuft (Iberis), rock roses (Helianthemum), and Lenten roses (Helleborus) are true evergreen plants.

Salvias, heucheras, some daylilies, low-growing sedums, some perennial geraniums and woodland phlox all remain at least partially green during the winter. Leave these to provide a bit of color in the winter garden. If care is taken to leave a variety of plants after the late fall chores are finished, the winter landscape will be filled with crystal-spangled stems, graceful bowing grasses and bright spots of green that promise spring’s arrival.

The winter garden need not be bare earth or simply a mulched bed. Add a few pansies, noted for their cold-tolerance, and you’ll be surprised to see spots of cheerful color on warm winter days and an early spring show that will last until nearly next summer.

After the ground freezes, usually after the winter holidays, a layer of mulch should be added to the garden to protect from repeated freezing and thawing that can cause frost heaving of plants.

Now that the beds are neat and ready for the wintry wind’s blast, the gardener has time to take stock of the garden that was and to imagine the garden that will be.

By Larry Hurley 

This is a quiet time in the garden, as October is moving into November, flailing about, looking for the end of daylight savings time which it seems to have misplaced somewhere.

In my shady perennial garden in Bethesda, Tricyrtis (toad lily) is still in bloom, but not much else is happening. Although we got 4 or 5 inches of rain last week, the soil is drier than I would have expected. It is critical that you monitor moisture in your garden as we go into winter. Evergreen perennials, trees and shrubs in particular must be watered during warm periods: winter damage to foliage and dieback of branches are most likely to occur when the plants are dry. Cold dry air and winds pull moisture out of leaves, and when the ground is frozen, the plants can’t absorb water. Plants that have taken up water prior to freezing fare much better than those that start out dry.

Leaves are turning and starting to fall.  Instead of taking all your leaves out to the curb, pile them up in a corner of the yard and compost them, or leave them in your flower beds.  Although you can increase the speed of composting, and the quality of the compost, with additions of vegetable matter from the kitchen, turning the pile, and loads of other tricks, you can do well with just plain leaves, piled and ignored. Eventually they will decay and can be spread back onto the garden. Don’t leave them on the lawn overwinter, as they may mat down and kill the grass.

If you have had disease problems with some plants, such as blackspot on roses, then leaves from those plants should be removed from the garden if possible, as they often contain the spores for next year’s infection. Good luck on that: I always found that advice easier to give than to follow.

If you are in the neighborhood of our garden centers, our perennials are on closeout, 40% off. In early November, we will ship the remaining plants at Potomac to our Beltsville store to overwinter.  We still have several thousand plants, best selection at Beltsville, with a good selection of hosta, asters, hibiscus, silphium, and coreopsis among others. You can plant as long as the ground isn’t frozen, although if you plant quite late (say the end of November or December), you will want to watch for frost heave.

I have found that as I get older, I lose the spirit to plant in the fall, even though it is an excellent time to plant. I usually overwinter a load of perennials in their pots, on the ground, covered with about 6 inches of tree leaves. For the most part they overwinter fine, and when I am mentally ready to start planting again, I have well-established (and cheaper plants from the fall sale) ready to go.

Enjoy your fall garden, take advantage of the nice days, and watch out for that change back to standard time. 

Notes from a Perennial Optimist
Once Again, our Larry Hurley is Out Standing in the Field

Fall is here, and we encourage you to break the football habit, get out into the garden, and enjoy the weather.
Soon, summer will just be an ugly, dry little blur through the rear view window of life. Autumn is a great time to become acquainted with some new perennials-some brand new, and some that you may have overlooked in the flurry of spring.

Ornamental grasses are mostly full-sun plants, but for the “grass look” in a shady spot, try one of the sedges (Carex). Two new ones for fall are Carex `Silver Sceptre’, variegated sedge, a short, clump-forming plant with ¼-inch narrow leaves with white margins. This really helps brighten up a dark corner. Another is Carex `Gold Strike’, growing to 10 inches, with golden-variegated leaves. For sun, look for cultivars of the native Panicum virgatum, or switch grass. Besides the popular `Heavy Metal’, there is `Shenandoah’, `Dallas Blues’, `Northwind’ and `Prairie Sky’. All are tall, late-summer to early-fall bloomers with airy plumes of bloom. Differences tend to be in intensity of leaf color (green to blue to purple) and fall color (yellow to red). Perennial geraniums are staples of the garden, and a couple of new ones have great potential. Geranium maculatum `Espresso’ was recently released by Dale Hendricks of North Creek Nurseries in Pennsylvania. This cultivar has pale lavender-pink flowers over red-brown foliage. “A bold new look for our native cranesbill, useful for groundcover or shade garden feature plant”, according to Dale. Another geranium with some “buzz” is Geranium `Rozanne’. Growing 20 to 24 inches tall, it has deep blue flowers, and is said to have a much longer blooming period than most perennial geraniums.Brunnera, or false forget-me-not, is a spring bloomer which performs well each year and then sits back and sort of calmly waits until next year. Appreciated by gardeners for its nice blue flowers, we are happy to note that there is also a white-blooming cultivar, `Marley’s White’. Horticulturists being what we are, we are also always looking for a little leaf-action in addition to breakthroughs in flowers. Until a few years ago, it was difficult and expensive to get variegated brunnera; now it’s only expensive. ’Jack Frost’ (“This plant displays a frosty silver overlay with light green venations. Leaves resemble crackled porcelain and shimmer in the garden creating a shining contrast against companion plants and its blue spring flowers.”) Pennsylvania perennial potentate David Culp attests that `Jack Frost’ looked terrific in his garden all summer and enthusiastically endorses it.Spigelia marilandica (“woodland pinkroot”; that’s catchy) isn’t “new” per se; in fact it is a native. But until recently it has been hard to propagate so it wasn’t seen frequently. The code has been cracked, and now you too can plant this summer bloomer with intense red and yellow tubular flowers that look almost tropical. Growing best in light shade, spigelia is a “hummingbird magnet” according to West Virginia plantsman Barry Glick. A slow grower, spigelia needs a couple of seasons to look really top notch.