Gardening success in the heat requires that plants have enough water to keep hydrated, and shade protection from the scorching sun to stop them from wilting and scalding. Certain flowers and vegetables grow well when temperatures are 90 degrees F and higher. Providing water at the root zone, where the plants need it most, conserves the amount of water used. Native species that are drought and heat tolerant are a good choice for areas that experience frequent hot temperatures.
When temperatures are more than 90 degrees F, heat stress, withering, and disease can damage, and even kill, plants. Plant tissues will become dehydrated and will cease to function if not provided with 1 to 2 inches of water per week. Bright sunshine can scald plant leaves, killing them. Shady areas under the north eave of a house or under a tree are areas that provide cooler shade for plants to grow in. Plants succumb to disease easily when stressed.
Supply 1 to 2 inches of water per week via an in-line water timer attached from the house line to soaker hoses lying under a mulch layer. A butter tub under the soaker hose helps to measure water emitted. Another method is to cut the bottoms off 2-liter plastic bottles, poke holes with a nail at the spout end, and bury them in the soil every 3 feet, next to plants. Fill with water twice a week.
Cool, refreshing shade provides shelter from direct sunshine. A nearby tree or the north side of an outside wall reduces sun-scald during the day and is an ideal place for plants to be located during summertime. Flower pots and containers provide the option of relocation to sunny or shady areas. A bench in cool shade under a tree is a perfect place for either flower pots or for a gardener to refresh with a glass of water.
Heat Resistant Flowers
Flower varieties that remain bright and happy in the heat are begonia, black eyed Susan, coreopsis, cosmos, hibiscus, marigold, periwinkle, portulaca, rudbeckia, roses, 4-O'clocks, salvia, sunflowers and zinnias. Heat and drought resistant types such as these bloom well from July through September and are proven performers. In Southern Texas, Southern California, and Southern Florida, these flowers grow well in light shade. Drought-resistant native plants from your region are great choices and are available at native plant nurseries.
Heat Resistant Vegetables
Successful vegetable crops for summertime can be harvested from these heat lovers: amaranth (aka callaloo), black-eyed peas, cucumber, crowder peas, Chinese spinach, Chinese asparagus pea (goa pea), Chinese yard long bean, eggplant, Malabar spinach, melons, mustard greens, New Zealand spinach, okra, peppers, summer squash, sweet potatoes and watermelon. Vegetables love growing in loamy soil, compost, and earthworm castings, as they hold water like a sponge, and are best applied around the plant's root zone to provide needed nutrients and good soil tilth.