Most Americans experienced one of the hottest summers on record last year, and die-hard summer vegetable gardeners were more intimately tuned into the heat — spending untold hours watering and nurturing crops through the worst of the weather. This year, wise gardeners will enter the season prepared with proven heat-tolerant summer vegetables able to produce even through the worst heat waves.
Even among warm-season vegetables, some are more resilient to harsh, hot growing conditions than others. For example, not all tomatoes and peppers continue producing fruit once temperatures exceed 95° Fahrenheit, while others seem made for hot days and nights. Likewise, some bean and squash species are better adapted to heat than others.
Over the years, researchers and trial gardeners across the country have tested many vegetables for heat tolerance, with some varieties showing exceptional resilience. Then there are those popular southerly vegetables that everyone knows make good in the heat.
Summer Vegetables for Heat
Here are some “hot,” reliable favorites to consider adding to your midsummer garden this season.
The unique red leaf vegetable amaranth (Amaranthus tricolor) is like most amaranths, tough and resistant to both high heat and moderate drought. Its tender green leaves have reddish-purple inner markings and a flavor comparable to spinach. Young leaves can be eaten fresh in salads or sautéed like spinach or Swiss chard. It is a must-have green for the sustainable vegetable garden.
Beans are favorite summer vegetables, but the vigorous, vining asparagus or yardlong bean (Vigna unguiculata ssp. sesquipedalis) grows particularly well when daytime and nighttime temperatures are high. Asian in origin, it is widely cultivated in both temperate and tropical Asia. Its tender pods grow to great lengths of 16 inches or more, and vines begin to produce very quickly in warm weather—usually only two months after planting. When picked young and tender, the beans are wonderfully crisp and flavorful, and well-harvested vines produce longer-than-average pole beans, even in scorching hot, humid weather. The purple-podded form is particularly high-performing, tasty, and loaded with nutrients.
Similarly, the sweet, non-bitter, Southeast Asian eggplants are some of the most delicious and best adapted to high heat. Two of the finest varieties for flavor and performance are the tender, long-fruited ‘Thai Long Green’ (8-10” long green fruits) and Taiwanese ‘Ping-Tung Long’ (12-16″ long purplish-red fruits). Both are mild, thin-skinned, and produce reliably in sweltering weather.
Peppers, sweet and hot, are always good for a very warm warm-season garden. Hot peppers are especially reliable in the heat; three highly recommended varieties include the super spicy classic jalapeno ‘Tula’, wonderfully flavorful pasilla-type pepper ‘Holy Molé’ (2007 AAS Winner), and classic spicy-sweet red bell pepper ‘Mexibell’ (1988 AAS Winner). Of the sweet bell peppers, nothing beats the tough, disease-resistant ‘Orange Blaze’ ( 2011 AAS Winner) and its crisp, bright orange peppers.
Okra (Ablemoschus esculentus) is the poster child for deep southern cooking and hot, humid summer weather. When choosing an okra variety, it pays to choose a spineless variety with pods that remain tender. Two winning cultivars are the very tall (5 to 8’), high-producing ‘Emerald’ and the compact, high-performing ‘Annie Oakley’, which bears loads of tender green pods.
Sweet potatoes are another southern favorite that won’t flag when the temperatures rise. Space-saving bushy (rather than vining) varieties tend to be most desirable for home gardeners, and of these, ‘Carolina Bunch’ and ‘Vardaman’ are two of the best. The disease-resistant ‘Carolina Bunch’ is highly productive, offering loads of pale-orange-fleshed tuberous roots, or “potatoes.” The equally productive ‘Vardaman’ has deepest orange sweet potatoes with award-winning flavor. If planted along berms amended with Black Gold® Garden Compost Blend, both varieties will bear loads of roots, even in the worst summer heat.
When it comes to tomatoes, a few perform exceptionally when summer days exceed 95 degrees Fahrenheit and nights remain warm, while most simply stop growing until scorching days subside. A great classic red slicer for heat is ‘Heat Wave II’, which bears meaty, flavorful, medium-sized tomatoes, even in 100 degrees Fahrenheit heat. And luckily, the finest tasting cherry tomato, ‘Sungold’, just happens to be a top performer in hot weather. Its bright orange, super sweet, highly flavorful fruits resist cracking and are produced in profusion. The 2013 AAS award-winning cherry tomato ‘Jasper’ has also been shown to perform well under stressful summer weather conditions.
Zucchini and Summer Squash
Summer isn’t summer without summer squash, and the best-of-the-best for taste and heat tolerance, high yields, and good flavor is Zucchetta Rampicante Tromboncino (Cucurbita moschata ‘Tromba d’Albenga’). The vines are large and rambling, but they produce delicious, long, curved summer squashes all summer — through hot and cool weather — up until frost. Towards the end of the season, let a few hang on the vines until their skin hardens. These can be saved and eaten as winter squash.
Caring for Summer Vegetables
For best plant health and yields, be sure to feed all your vegetables with organic fertilizer early in the season. Amendments such as Garden Compost Blend and Earthworm Castings Blend will also ensure your plants thrive by maintaining proper soil moisture and aeration. Doing this will encourage vigorous root growth. Double–digging is another great way to optimize health, deep root growth, which enables plants to better withstand moderate drought and high heat.
Get this summer’s crop started off right with a well-prepared garden by planting tougher, heat-tolerant summer vegetables, and this year’s yield is sure to beat the heat.