Behnkes Late Spring 2008 GardeNews

Behnke GardeNews is now available for download on our main website. All of the articles in our newsletters will be published online here within a few weeks, but you can get your copy  now by going to our web site and downloading the Behnke GardeNews today!

Click Here for a direct link: Behnke GardeNews

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.

Plant Ghosts of A Christmas Past
by James Dronenburg, Plant Specialist

Let’s remember the plants of Christmas past. They aren’t with us the way they used to be. The reason? People’s houses then were cold, by our standards. Early houses had fireplaces—the earliest had huge, walk-in hearths—which did triple duty in cooking, washing, and heating the room. The open fireplaces sent huge quantities of heat up the chimney, rather than into the house. In the 1700’s, stoves started to come in, and the houses could be heated more efficiently. Furnaces came in by the late 1800’s, but windows were uninsulated—ditto the walls and roof! (They used far less light than we do, too. More later.)

People thought nothing of this; it was the norm. They just wore more clothing. But these conditions—not freezing but cold by our standards—let them do a lot of things that we find hard today. They kept all sorts of plants in their windows, which tended to have nice deep sills. Things like primrose, cyclamen and gardenia were very popular, because these plants need cool night temperatures and a fair bit of temperature change between the day and night. They forced bulbs more easily, because the bulbs were not blasted by our hot, dry air. The average cooler house of yesteryear had far more humidity. As a general rule, the plants that were favorites then were favorites because they did well in those conditions.

“Let the windows be well stopp’d up at night, so that water does not freeze, and there needs no fire.” (Advice over two centuries old)

Some plants, such as geraniums, survive today. They can take the dry heat; they were desert plants to start with. But the Christmas cactus, for example, needs a cool-night temperature, or failing that, a long period of darkness, to set bud. Lamplight across a warmer room wasn’t enough to mess with their little green minds, but electric light is. The best place for a Christmas cactus is, in fact, an unused room that you don’t go into very much. (Quite a few orchids, by the way, also like a day-night temperature change.) They could have roses in sunny windows, and gardenias too. Gardenias will take night temperatures down into the high 50’s without dropping their buds—but in a modern house, drop they will.

People— including my own great-grandmother, in Adamstown, Maryland — grew citrus trees, orange and lemon, in large tubs. Down they went to the basement for the winter, and stayed dormant. More affluent people put them in rooms with large south windows, and they did not go dormant. The trees did very well in the cold. Often there was a bay tree or a pot of rosemary upstairs on the windowsill.

These will dry out at the drop of a hat nowadays. And to add a nasty non-holiday note, you will find that a hot, dry house encourages the spread of spider mites and/or mealy bugs. Give your plants the occasional mist or a shower right in the tub to stave this problem off, this is a crutch not a cure, and consider putting gravel in their saucers or trays to let a little water stand in without rotting their roots off.

The grizzled of pelt among us, of my age and older, will remember Christmas greens lasting longer. This isn’t just a reminiscence — with forced air heat things dry out quicker. If you have the time, take your Christmas greens and mist them or lay them in water for an hour or so on occasion. You can also give greens a misting of Wilt-Pruftm, which cuts down on transpiration of moisture into dry air. You can’t untrim your tree and do that to it—but you can make sure that its pan of water is full at all times. And, with a living tree, try to lower the temperature of the room.

Outside and in, we trim with greens. Henry Mitchell (whose columns for the Washington Post have been reprinted in three books, The Essential Earthman, One Man’s Garden, and Henry Mitchell On Gardening—these are must-reads— see page 6) in his time mentioned five generally accepted “traditional” greens—rosemary, bay, holly, ivy and mistletoe. He personally considered yew, box and juniper “equally necessary.” Odd, very odd, that he did not mention four others, mainstays around here, pine, spruce, Magnolia grandiflora and crowsfoot. And occasionally you see wreaths and swags of mountain laurel used. Most of these greens will last longer with lower temperature and more humidity — even the greens used outside will benefit from the occasional sousing-down, and/or a bit of Wilt-Pruftm applied after the soaking.

Your great-grandmother would have had fits at the very idea of a throw-away plant.

We still trim our houses, but we tend to use things like poinsettias which are bred and greenhouse-grown for modern conditions. We couldn’t grow these ourselves. (You can bring a poinsettia into flower. Put it in a room where there is no light between sunset and sunup. But let it get one good flash of light in the middle of the night, and pfui! It thinks it’s summer and cramps up, at least for that night. If you’re in that room with the lights on regularly, the thing will not color up.) And we buy holiday plants to throw away, because we can. Because the plants are there, easy and available. Gardenias, cyclamen and chrysanthemums are still here—but are grown to be thrown away after flowering.

Amaryllis are with us still; they are tropical bulbs with a waxy covering on their leaves, and take no guff from anybody. Let them flower, keep watering and fertilizing for the months it takes until the foliage goes yellow on its own, and your bulb will last longer than you will, and multiply. These days the mini-amaryllis are the rage. They take up less space, can be used as a centerpiece, and are very forgiving. These mini-amaryllis come from species that actually have been in general circulation for over a century, did you know? I had one in the late sixties, from my junior high school librarian; it had been passed along in her family forever. Thought I’d never lose it…gave away the babies…lost it. Rats.

We have filled the space our ghosts left behind. Orchids are popular nowadays, especially the forgiving, high-temperature ones like phalaenopsis. They are spectacular in the variations available now, and bloom for months. Other plants, like kalanchoe, have made the transition by being bred down to a better size and lots more colors. (An old fashioned kalanchoe is fire engine red and about two feet high.) Being succulents, hot dry air holds no terrors for them.  

But… Would you like to try your hand at the things your grandmother had for the holidays? Make a cool spot in your house. It may be as simple as turning down the air flow or the baseboard in one room, and shutting the door; it may be rigging your curtains so that they can be shut at night with your plants between them and the windows. I have, in my own house, two rooms so shut off, and in them I can put forced bulbs and they last and last; in a still room, the fragrance is unbelievably good. I buy cyclamen for the holiday season and they bloom until April or May. Some of the orchids, the miltonias and the tiger orchids, like the cool. Overwintering plants like gardenia, brugmansia, and Christmas (Thanksgiving, Easter) cacti will thank you profusely. And you can enjoy the “ghosts” of Christmas past once again.

Holiday Greenery

This year, treat your family to the finest possible Christmas tree – a Behnke tree! Behnke Nurseries carries a large variety of trees such as Fraser Fir, Balsam Fir, Douglas Fir, Noble Fir and Grand Fir in a wide range of sizes. We carry only the finest quality trees, harvested at the last possible moment to insure that all of our customers receive the freshest and most beautiful cut tree available.

Choose from the area’s finest selection of wreaths, roping, swags, candle rings and other specialty items. If you desire, our award-winning designers will create the perfect wreath to suit your holiday decor. Or make your own with our fresh-cut evergreens including Port Orford Cedar, Holly, Boxwood, Magnolia, Incense Cedar, White Pine, Winterberry, Silver Fir, Juniper, and Concolor Fir.

Sharing of the Greens
by Larry Hurley, Horticulturist

The celebration and symbols of the Christmas holiday are of complex and multiple origins. Many ancient peoples observed the winter solstice, the shortest day of the year, honoring their gods to ensure that the days would again grow longer and winter would pass to spring. Romans had the Saturnalia festival to honor Saturn, the god of time. It was held in December, and placing Christmas at this time of year grew out of this rambunctious Roman holiday.

Plants used for modern holiday decoration played a part in ancient religious celebrations. Evergreens were of particular interest to the ancient Europeans, as they symbolized life in the midst of winter death. The Romans considered holly to be a plant sacred to Saturn, and holly wreaths were given as gifts at the Saturnalia. Holly was adopted by the Christians, who not only used its prickly green leaves and red berries to symbolize the Crown of Thorns, but also believed it was the wood used to build the Cross.

A charming tradition in England is for beekeepers to put a sprig of holly on their beehives. It is said that in the manger in Bethlehem, bees “hummed in honor of the Christ Child.” You can almost hear them humming as an undercurrent to “Pa-Rum-Pum-Pum-Pum.”