Roasting Vegetables: Managing A Garden in Hot Weather

wilted tomatoes

Wilting tomato plants

by Elizabeth Cornell Fake, Fairfax Master Gardener
In case you haven’t noticed, it is hot in your vegetable garden. A beautiful, balmy May in Virginia’s Zone 7 has turned into the humid inferno of June, July and August. With temperatures fluctuating from 90+ degrees during the day to 75+ degrees at night, torrential rainstorms and 3 to 5 day periods of drought, it should come as no surprise if your vegetables are struggling. Signs of stress are abundant including production of poor or sterile pollen, failure to blossom and set fruit, poor quality fruit, sun scalding, blossom end rot, fertilizer burn, powdery mildew, fungal diseases and the arrival of deadly insects. It is a war, but you can win with some advanced planning and disciplined gardening practices.

Here are some tips for making sure your garden is the place for your prize vegetables to grow.

Plan Ahead — It is not a secret the summer will be hot, damp and humid. Since you know in advance, prepare your vegetable beds by having the soil tested by the Virginia Tech lab in the spring, adding compost to the soil and following directions from the soil lab about the additives, nutrients and fertilizer needed to grow healthy vegetables.

Research Heat Resistant Plants — Some plants thrive on sun and warmth, and it is good to keep them in mind as the baseline of your vegetable garden. These include Cowpeas, Yardlong Beans, Okra and Sweet Potatoes. Others include species bred to withstand heat and humidity. Many commercial plant catalogs or websites identify heat resistant cultivars. Take some time to look at what is available both by mail order and in your local garden center. Here are some suggestions to get started: Malabar Spinach (Basella alba), Summer Squash, all varieties of Peppers, Cherry Tomatoes, Eggplant, Cucumbers, Swiss Chard, Kale, Collards, Watermelon, and Pumpkins.

Consider Planting Quick Maturing Plants — These are vegetables you can harvest before the sweltering drought begins. Plant them in the spring as soon as the danger of frost has passed and within 55 to 65 days of transplant, they will be ready for the table. Here are a few of the many tomato cultivars that mature and produce fruit by early July: Solanum lycopersicum ‘Early Girl,’ ‘Fourth of July’ and ‘Juliet.’

soaker hose

Soaker Hose for watering

Use Mulch For Temperature Control –- As you are planting your heat resistant vegetables, keep the garden mulched to conserve water and discourage weeds that will compete for soil nutrients and water.

Water To Win The Day –- Avoid overwatering. Watering two to three times a week should be enough to keep the soil damp unless there is excessive heat or long periods of drought. Aim for 1 inch of water a week or 6 gallons of water per square yard. A good test for soil dampness is to dig 2 inches down to see if the dirt is wet at that level. If it is dry, then it is time to water. Sandy soil dries fast but clay soil will retain water longer. Newly planted seedlings and seeds need more water than established plants. Watch for wilting and water as soon as possible. Water in the morning by 9 a.m. using a soaker hose if available, aiming at the plant roots. Avoid overhead sprinklers that will leave too much water on foliage and encourage fungal diseases, mildew and blight.

testing vegetable shading

Testing various vegetable shading

Consider Shading Systems — Create shade for hot plants in several ways. If you are using containers, move the containers to a shady spot for the evening hours. Shelter hot plants by covering them with an inverted folding chair. For caged tomatoes, tuck the leaves growing outside the cage back into the metal structure to create a dense layer of protective foliage. Tomato enthusiasts boast spectacular results through the use of commercial woven or knitted shade cloth systems available from gardening centers or online outlets.

Be On The Watch For Fungal Disease and Pests –- In the heat they are just waiting for an opportunity to strike. As part of your garden plan, be sure to space plants the recommended distance apart to encourage airflow between plants. Prune lower leaves on squash and tomatoes to improve circulation. Apply organic fungicides such as copper spray or neem oil as a preventive measure. When common pests such as aphids, spider mites, flea beetles and squash bugs arrive for dinner, hand pick them off and apply insecticidal soap or neem oil to discourage their presence.

Encourage Abundance — Hot weather promotes the rapid growth of vegetables. Harvest frequently when fruit begins to mature. Do not let squash and cucurbits grow to gigantic size which will inhibit the growth of other fruit. If vegetables aren’t thriving, pull them out and replace them with new plants.

Take Care Of The Gardener — Don’t forget gardening is hard labor and in hot weather, the gardener needs care, too. Try to space out gardening chores over several days a week for one or at most two hours before the heat of the day begins. Wear a hat and loose clothing, drink lots of water and take frequent breaks in the shade to read your new vegetable catalogs, rest and relax.