Selection and use of stress-tolerant bedding plants for the landscape

NC STATE UNIVERSITY Horticulture Information Leaflet 552 Revised 8/99 -- Author Reviewed 8/99 College of Agriculture & Life Sciences Department of Horticultural Science Selection and Use of Stress -Tolerant Bedding Plants for the Landscape Douglas A. Bailey, Professor m ftj Ш A What is Stress? Each of us are subjected to stresses and pressures every day in our home, work, and living environment; plants are no different. Unfortunately, there is no “stressless” environment, and there is no totally stress-resistant bedding plant. Each site has its stress level and each plant has its tolerance level. There are steps that can be taken to reduce or avoid stress in the landscape. However, no program can prevent all problems, and the key to successful landscape color using bedding plants is to match the particular site with specific plant species. But before you can select plants to use, the site should be accurately analyzed and characterized, and preparations should be made to minimize stress conditions that may occur. Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age. or handicap. North Carolina State University. North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating. Characterization of the Landscape Site A site analysis for bedding plants should include ® temperature averages for the color season, d> amount of sunlight received daily, ® rainfall averages and average intervals between rains, and ® soil characteristics such as drainage and moisture retention. Each of these components should be further defined prior to plant selection. Temperature. Very few species look attractive and flower profusely from early spring through late fall, and rotational planting for continuous color should be considered (Table 1.). Cool-season flowers STATE UNIVERSITY A&T STATE UNIVERSITY COOPERATIVE EXTENSION Helping People Put Knowledge to Work such as dianthus, snapdragons, and pansies can be used early in the season. It is possible to extend the flowering season of cool-season annuals by placing them in a protected location, shaded from direct sunlight from 12:00 to 4:00 pm. Heat- loving flowers such as gaillardias, portulaca, sand verbena, and vinca do not begin to flower until early summer and should be used for summer color and high temperature situations. Heat tolerance is an advantageous characteristic, and bedding plant trials can offer cultivar suggestions to landscapers interested in plant performance in high temperatures (Table 2). Another temperature consideration is frost tolerance (Table 1). Avoid early planting of tender plants to prevent frost damage. Tender species also will be the first to be killed from frosts in the fall. Light. Light and temperature are closely related, and plants listed as preferring lower light may tolerate more sun, if temperatures are moderate. When evaluating light exposure, note the duration and intensity of light the site receives. Four hours of full sun during the morning is much different than four hours of afternoon sun. Also, in a shaded location, the degree of light filtration can vary. In general, if the site receives more than 3 hours of unfiltered mid-day sun, it should be treated as a “full sun” site, with respect to plant selection (Table 1). “Partial shade” can be defined as receiving