Last week brought the first truly hot spell of July with several days above 100 degrees and nighttime temperatures dropping only to the 70s. Cooler than normal spring weather in April, May and June slowed the normally rapid growth of heat-loving summer vegetables, but did allow for very good vegetative growth and flower production. If July and August temperatures continue to remain within the normal really hot summer range, our vegetable plants will undergo changes these next weeks.
Eggplants and peppers require warm to hot weather to produce well. They will continue to set and hold fruit with temperatures up to 100 degrees, but when temperatures rise above 100, fruit set, flowering and pollination slow down. Because of the cooler spring weather this year, many eggplants and pepper plants are slightly stunted. Really hot weather such as we had this last weekend will also slow growth and flower production again. That may mean smaller than usual crops this year. Like tomatoes, eggplant and pepper flowers are self-pollinating (no need for insect pollinators); shake the plants daily at midday to release pollen from flowers that are still holding on.
Tomato blossoms drop when temperatures are above 90 degrees. The fruit will ripen so quickly that cracks can form in the skin. Keeping the soil around tomatoes consistently moist is key to preventing cracking. Cracked tomatoes are still edible; just cut around the cracked areas. Lightly tap, shake or tickle any remaining tomato flower clusters to loosen wind born-pollen and encourage pollination. In our climate, we often get two harvest seasons of tomatoes-the first in late June/early July and the second starting in September and lasting through the warm fall days.
Many varieties of beans and cucumbers, which are warm-season vegetables, become heat-stressed during our hot summers. With heat stress comes pest insects, especially whiteflies, mites and aphids and the diseases they carry. Pull out bean plants when they fail to set pods or if leaves dry out. Beans can be replanted from seed again in August for a successful fall, warm-season crop.
Cucumbers are members of the cucurbit plant family which also includes squashes and melons. Cucurbits are pollinated only by bees and by humans with an artist’s paint brush In hand. In hot weather, bees tend to stay home and fan themselves to stay cool. Cucumbers will set few if any flowers in hot weather. Cucumber plants should recover vigor as temperatures cool in late August and early September. Keep the soil around them consistently moist and provide afternoon shade to protect them from the summer sun’s intense rays.
Check heat-stressed plants often for signs of pest insects. Look for aphids inside curled leaves and wash them off with a gentle spray from the hose. Use a dedicated handheld vacuum to suck up whiteflies as they fly up from infested plants or place yellow sticky traps around the edges of the vegetable patch and replace the traps when they’re full. Wash dust off plants and check the undersides of leaves for the webs of red spider mites. Mites can be washed off with water, killed with insecticidal soap or smothered with neem oil.
Harvest all summer vegetables regularly. Letting old vegetables rot on the stem slows plant growth.