Gardenias need much care in our climate
Gardenias are one of my favorite flowers, but caring for the plants is tricky business. Gardenia jasminoides is a beautiful tropical plant that produces pure-white blooms with a heady fragrance. The dark-green, glossy leaves are another lovely feature, making the plant quite attractive even when it isn't in flower.
In the Southern United States, where the plants are fully hardy, gardenias grow outdoors and can reach up to 6 feet in height. But here in Pennsylvania, where they will not survive the winter, they are grown as a houseplant, though they often spend their summers outdoors.
To best care for a gardenia during the winter months, provide it with plenty of bright light (preferably in a west- or south-facing window), moderate humidity and cooler temperatures. Ideal winter daytime temperatures for gardenias are between 55 and 65 degrees. Because gardenias prefer cooler temperatures and moderate humidity, keep them away from heat registers and other drafts. To increase the humidity around the plant, set the pot on rocks or pebbles in a tray of water, but do not allow the base of the pot to sit in the water, as this will cause the roots to rot. You also can mist your gardenia with chlorine-free, room-temperature water every morning.
Provide water when the soil is dry to the touch and the pot feels light by moving the plant to the sink and allowing the water to flush through the container. If the plant dries out, the buds will drop. On the flip side, overwatering will cause the leaves to turn yellow and fall off.
Fertilization should only take place from April through August in the form of monthly applications of a liquid fertilizer designed for use on acid-loving plants. Do not over-fertilize. Doing so attracts pests and causes salt to build up in the soil.
During the growing season (from mid-May to early September), move gardenias outdoors. Put the plant in a shady spot, away from any direct sunlight, and keep it well-watered.
To control spider mites, scales, aphids,and other pests, examine the plants on a regular basis. Because gardenias are sensitive to many chemical pesticides and miticides, you should avoid using them. Before bringing plants indoors for the winter, spray them with a sharp stream of water from the hose to dislodge any pests. You can also put the plant in the shower and gently wash or wipe the pests off the leaves.
Ultrafine horticultural oils are an option if the infestation is difficult to control. This lightweight oil smothers and kills many different pests and is not harmful to humans or pets. It must be applied to both upper and lower leaf surfaces, as well as to stems. Be sure to read and follow the label instructions carefully and confirm that the brand you choose is labeled for use on gardenias.
Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio. She is the author of several gardening books, including “Attracting Beneficial Bugs to Your Garden: A Natural Approach to Pest Control” and “Good Bug, Bad Bug.” Her website is www.jessicawalliser.com.
Send your gardening or landscaping questions to tribliving@tribweb.com or The Good Earth, 503 Martindale St., 3rd Floor, D.L. Clark Building, Pittsburgh, PA 15212.
