[title subtitle=”words: Megan Lankford, Horticulture Supervisor,
Botanical Garden of the Ozarks
Most of us have heard of the USDA cold hardiness zones map. This map tells you what zone you’re in, and you can then see if what you want to put in your yard is hardy in that zone. While cold tolerance is very important, gardeners must also consider heat tolerance. A plant may be able to survive the winter cold, but not the southern summer sun.
There is a new map from the American Horticultural Society that tells you what heat zone you live in. The heat zone is based on the number of days in an average year that are above 86 degrees, which is the temperature at which many plants begin to suffer. It is set up similarly to the USDA cold hardiness zone and is easy to use. This system has not been adopted by all nurseries yet, but many have, and you can find the information on the plant tag. If the information is not available there, you can often find it with a quick internet search.
You may wonder why some plants wilt in the afternoon when the temperature is high. Plants transpire water to cool themselves, similar to human perspiration. While this works well most of the time, when the temperature rises above 86 degrees, some plants are unable to get enough water from the roots to keep up with the amount transpiring from their leaves. If you see your plants wilting, dig down a few inches in the soil, if there’s adequate moisture no worries. If not, you can water your plants, regardless of the time of day.
You Can Plant:
Arugula, Beets, Beans, Cucumbers, Peas, Radishes, Scallions, Spinach
Sow in Dappled Shade in Beginning of August:
Bok Choy, Broccoli, Cabbage, Collard Greens, Kale, Leeks, Mustard Greens, Onions, Scallions, Spinach, Swiss Chard
In late August:
Cilantro, Parsley, Dill, Fennel, Lettuce