Thursday, May 19, 2011
Plants for wet clay: Zenobia pulverulenta
After a few years of growth, this shrub has grown large enough to make a significant visual effect. Zenobia seems to be a rather rare plant in cultivation, and the glaucous form isn't the only one. Some are simply green. I bought two at the Native Plants in the Landscape conference, a well known native plant gathering held annually at Millersville University in Pennsylvania, three or four years ago.
I was uncertain how the plant would fair in my often saturated, wet clay; its natural habitat, which is wet but apparently well drained, very acidic and low in nutrients, is quite different from conditions in my garden. So far my Zenobias appear to be thriving, vigorous, and in pristine condition. Their small, bell-shaped white flowers are borne in profusion in the summer, and the plants are bulking up into admirable specimens.
The lesson, I suppose, is that you can research a plant's origins and native conditions, but you can never successfully predict how well it will adapt to differing conditions in the garden. You just have to make educated guesses, and see what happens. Take a risk. There are serendipitous surprises.
Friday, June 04, 2010
Change?
It wasn't anything I would have expected. I've been attending the Native Plants in the Landscape Conference since yesterday (it ends tomorrow). This conference, held at Millersville University near Lancaster, Pennsylvania for the past 20 years, is one of the major native plant conferences in the US. Until this year, I've felt something of a heretic, never having been a purist where use of native plants is concerned.
This year there appears to have been a programmatic effort to question the lock-step approach to "natives only" that has characterized the native plant movement for so long in this country. This year, a definite theme seems to have emerged, beginning yesterday with the keynote talk by William Cullina, a well known author and Director of Horticulture/Plant Curator for the Coastal Maine Botanical Gardens. The title, "Unraveling and Re-raveling the Web of Life," only hints at a message I think long overdue--that the very concept of native plant is a changeable thing, subject to the changing conditions of the earth, in different times and places. Plants move in response to these changes, and their native ranges change over time. Cullina gently but persuasively broadened the definition of native, raising such difficult questions as whether isolated pockets of native vegetation on their way to extinction should be moved to new places, where the climate and conditions are more suited to their needs. The thrust of his talk was that the definition of what is native is not a simple or easy question to answer.
The second keynote talk of the day, "Perennial Plant Communities: The Know-Maintenance Approach," was really about plant sociology, plants growing in communities, though the word sociology was never used. (I think even our "experts" feel they have to be gentle, and do a little "dumbing down" to avoid alienating North American audiences.) This second keynote talk was given by Roy Diblik, co-owner of Northwind Perennial Farm in Wisconsin. Roy is the man who supplied Piet Oudolf with plants for the Lurie Garden in Chicago's Millennium Park, and he is quite a garden designer in his own right, having recently designed beautiful plantings for the Chicago Art Institute. He spoke about the necessity of growing plants in plant communities (another very important theme of this year's conference), and the need to move away from the awful American compulsion to dot a few plants about amid mounds of wood chips and mulch, toward a more natural style of planting based on intimate knowledge of plants and their individual needs. Roy's approach is very closely akin to the approaches to planting design I've read about for years in the works of English garden writer Noel Kingsbury, Piet Oudolf, the American design firm of Oehme & Van Sweden and, of course, many others in the "New Perennials" movement, and, before that, in the seminal work Perennials and Their Garden Habitats, originally written in German by Richard Hansen and Friedrick Stahl, and first published in English in 1991. The concept of plant communities, or course, raises the bar, so that we think holistically about systems of life and not about just individual plants, how communities function and grow, and how much labor is involved in their upkeep (not a lot since stable communities don't require a lot of human intervention). Roy also struck an extremely romantic note, stressing the emotional component of beautiful, carefully orchestrated plantings, and noting how ugly some native plant restorations are--because no consideration was given to these broader concerns of the garden, the gardener, and the garden visitor.
The third keynote talk, by Niel Diboll, owner of Prairie Nursery, and an acknowledged leader of the native plant revival, particularly prairie plants, declared war on the American lawn. With a passion and style that reminded me of a bible thumping preacher on a revival crusade, Diboll enumerated the extravagant costs of the American lawn in terms of what he called the four Es--esthetics, environment, energy, and economics. He's convinced the American love affair with the useless, polluting, environmentally sterile (no, environmentally harmful), and costly lawn will end, not because Americans will be converted to more ecologically sound beliefs, but because the cost of maintaining this socioeconomic shibbolith is simply too great and it will eventually collapse under the weight of its unsustainablility. Diboll's vision to use native plants to help restore the balance of nature, and the sanity of our insane culture, reflects a profound understanding of the complexity of plant communities, and of the need to think about planting in terms of community.
Larry Weaner was the major speaker this afternoon. His ostensible subject was incorporating ecological restoration techniques into landscape design. He, like Roy Diblik, emphasized the importance of understanding the whole plant community and its behavior over time. Larry's talk was much more technically detailed than Roy's, and he demonstrated the immense knowledge needed to create a successful meadow. Near the end of his talk, he also introduced the concept of allowing a certain element of chance to participate in the design of a planting (self-seeded plants, or plants introduced by animal life), an intriguing idea for the more conceptually oriented gardeners and designers in the audience. Weaner's talk helped elevate the conference to a new level of sophistication.
It was heartening to hear Roy Diblik recommend one of Noel Kingsbury's books. In the past, the Europeans have been virtually non-existent at this conference ... are we, perhaps, about to break the blood-brain barrier between British (and European) gardening and American gardening? Whether this new direction at the Millersville conference illustrates a new direction in the native plant movement, a maturing of the movement in general, remains to be seen. But it is certainly a hopeful and exciting change.
Saturday, June 07, 2008
Native plants: gardening without guilt
C. Colston Burrell's opening presentation on the 20th Century Native Plant Movement in America was a refreshing, highly entertaining, and appropriately generalist take on this sometimes politically charged subject. Yes, native plants are important to maintaining local and regional ecosystems. No, we don't have to plant only natives so long as we are responsible and don't use species proven to be highly invasive and disruptive to the environment. Yes, aesthetics is a valid concern in gardening. After all, humans are part of the ecosystem too; we get to have a say. Yes, it's hard to define "native." But, no, the arrival of white Europeans on American shores isn't a good basis for a valid definition. Regional differences in plants, even plants of the same species, and local genetic provenance, are much more important.
This conference attracts numerous professional garden designers, experienced gardeners, and nursery men and women specializing in native plants, so the level of discourse tends to be quite high. I hope to report on one or two of the more specialized sessions I attended in another posting. I particularly enjoyed Don Knezick's "Genetic Integrity of Native Plants: Provenance is Forever" and Dr. Roger Tai Koide's "Mycorrhizal Fungi: Hidden Friends of Plants."
A highlight of this conference is the native plant sale, and it's one of the best. Nurseries from eastern Pennsylvania down into the Virginias offer perennials, shrubs and trees, many of which are rare in trade and difficult to find. I came back with four winterberry hollies (Ilex verticillata) - nothing rare in that selection but needed in my garden nevertheless, five Iris versicolor of sufficient size to divide into ten plants to join my late May/early June iris splash, two sizeable copper irises (Iris fulva) to go by the pond, two "Dolls eyes" baneberries (Actaea pachypoda) for the woodland garden, one Sagittaria latifolia to go into the pond, and ten Meehania cordata to try out as groundcover in the woodland. Okay, I confess, there's nothing particularly rare in my selections, but other offerings included Moosewood (Acer pennsylvanicum), various native gingers (formerly asarum, now hexastylis), all sorts of big leaf magnolias, Jeffersonia diphylla, and on and on.
If you live within driving distance of Millersville, consider the conference in 2009.
Friday, June 09, 2006
Plant Stewardship Index
We went to the annual Native Plants in the Landscape conference at Millersville University last week. I attended two presentations on the Plant Stewardship Index.
The name makes you want to run for your garden spade? Don't.
Though I do not limit my plant selections exclusively to natives, I understand the value of preserving local, native plant genotypes, fighting invasive alien species, and saving natural lands from development. We have two exquisite watersheds in our little part of New Jersey - the Wickecheoke and the Lokatong. Both drain somewhere around 25 square miles, and share a rocky, picturesque plunge over their last few miles into the Delaware. These two watersheds, and the surrounding lands - particularly the sublime Rosemont Valley - need to be preserved.
Several local governments and nonprofit organizations are having success preserving farms and natural lands. But as more and more land is preserved, and development forces exert pressure to take the land for their own benefit (profit), it will become increasingly necessary to be able to show the value of preserving land, and to clearly demonstrate that preservation measures are improving the value of these lands.
Thus, the Plant Stewardship Index. This is a scientific tool that can be used to evaluate the value of natural lands, and to measure the efficacy of management measures used to improve the quality of these preserved lands. The PSI provides an index, a number, that indicates the quality of native habitat by measuring the numbers of plant species present.
It is a highly localized tool because its foundation is a list of plants that grow in a specific area, both native and non-native, each with a number assigned between zero and 10. Plants that are native, and that indicate a high quality habitat by their simple presence, have higher values. Such a list - consisting of over 4,000 plants - exists for New Jersey. It was developed by professional botanists meeting and coming to consensus on each plant's value as an indicator of high quality habitat. A similar list for Pennsylvania will soon be available.
A mathematical formula is used to calculate the PSI. It looks a little foreboding because it incorporates a statistical technique to assure more accurate results, but it's quite simple. Of course, calculating a PSI requires you to perform a survey of the land, and to be able to identify the majority of plant species living there. You don't have to actually count the numbers of individual plants in each species, just the presence of a species.
Bowman's Hill Wildflower Preserve (BHWP), just south of New Hope, Pennsylvania, has taken on the challenge of introducing the PSI to our area. This is a major undertaking for such an organization, and they deserve support. Many governmental and academic organizations have declined take on introduction of the PSI in New Jersey and Pennsylvania, so BHWP is doing a really good thing. They will soon make available on their web page all the information needed to calculate the PSI for a given piece of land. I understand this tool will be available to the general public. BHWP will also give a series of classes in use of the PSI and identification of native plant species. I intend to participate.
Here is the BHWP web address. Keep a watch for the PSI tool to appear in the very near future.
Bowman's Hill Wildflower Preserve