When the glossy gardening catalogs come in the mail, or when you stop by to see what’s new at your local nursery, it’s tempting to dream—wouldn’t those pink-hued purple coneflowers be lovely in the front yard? Or what about that new, show-stopping snowflame hibiscus?
But before you grab your credit card, consider the pertinent question: which plant would work best in your garden? That’s where the Chicago Botanic Garden’s Plant Evaluation Program comes in. For more than three decades, the program has conducted scientific studies to determine which plants offer superior performance in the Upper Midwest and in areas with similar climate and soil conditions.
“So many plants have a premium price, and if they don’t perform as expected, people get disenchanted,” said Richard Hawke, plant evaluation manager. “You’ll find what’s hot and new in catalogs and magazines, but I’m all about the tried-and-true. We’re here to tell the average gardener and the green industry how plants performed in our evaluations.”
Few plant evaluation programs are as large or as diverse as this one. There are currently 30 groups of plants growing in the Bernice E. Lavin Plant Evaluation Garden, a 2.5-acre site in full sun, and in the William Pullman Plant Evaluation Garden, which has perennials, vines, shrubs, and small trees growing in partial shade.
Plants are rated based on their ornamental characteristics, how well they adapt to the site, whether they are winter hardy, and how well they resist diseases and pests. “When we look at winter hardiness, it’s not just for cold temperatures but for wet soil, which can be very detrimental,” Hawke said. None of the plants is treated for diseases or insects.
The length of the evaluation varies from four to ten years based on the type of plant. Perennials are studied for four years, while shrubs and vines are a six-year study, and trees may take seven to ten years. “We observe and review them over a long period so we can say with fair certainty how the plant performs for us,” Hawke said.
The results are published in the Garden’s Plant Evaluation Notes, a series of reports made available to home gardeners and the green industry and available on the Garden’s website at www.chicagobotanic.org/plantevaluation.
Hawke is also involved in evaluating the potential for some popular ornamental plants, such as maiden grass (Miscanthus) and smartweed (Persicaria/Polygonum), to be invasive. This is a concern not only for home gardeners, but also for forest preserves and other open spaces where invasive plants compete with native plants.
It’s easy for visitors to check out the plant trials underway—the Trellis Bridge connects Evening Island to the Lavin Evaluation Garden across from the Daniel F. and Ada L. Rice Plant Conservation Science Center, and there’s a new path within the evaluation site. “What’s great about the evaluation gardens is they are densely planted with things that you won’t necessarily see anywhere else in the Garden,” Hawke said. “You can see a group of different filipendulas or lavender growing side-by-side.”
The Plant Evaluation Notes are made possible in part by the Woman’s Board Endowment for Plant Evaluation Research and Publication. This post was adapted from an article by Nina Koziol that appeared in the winter 2013 edition of Keep Growing, the member magazine of the Chicago Botanic Garden.
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