My neighbors and I count the flowers and the tiny tomatoes on our vines every day. Daytime temperatures in early June are beginning to climb toward 100 degrees and nighttime temps remain above 60 degrees affecting flower production and retention on many summer vegetables. The tomatoes (and cucumbers, melons, beans and squash) we have ripening on the vine now may be the only ones we’ll have to eat until temperatures begin to cool again in late August.
Tomato flowers will drop when daytime temperatures are regularly above 90 degrees. Hormone sprays to help flowers set fruit without pollination are no help in hot weather. Keeping the soil consistently moist will help flowers hang on. Irrigate tomatoes (by hand if need be) when the top inch of soil has dried. Tomato plants need about 2 gallons of water per week.
Tomatoes are sensitive to high amounts of nitrogen and will produce more vine than flowers when high nitrogen fertilizers (above 5 percent) are applied or when planted in locations where beans and peas were previously planted. (Beans and peas fix nitrogen into the soil.) Switch to a low-nitrogen fertilizer with high percentages of phosphorus which promotes flowering or apply a few tablespoons of bone meal, bulb food or bloom food (which also have high percentages of phosphorus) or a cup of compost monthly. Bone meal and bulb food also contain calcium which is the remedy for blossom-end rot in tomatoes. Blossom-end rot causes the bottom end of the tomato to turn gray and mushy. The unaffected portions of the fruit are still edible.
Melons, cucumbers and squash
Melons, cucumbers and squash are all members of the cucurbit family which are pollinated only by bees. Bees slow their pollination work during hot weather. Partial pollination by heat-stressed bees causes misshapen fruit and poor yield.
Members of the cucurbit family bear male and female flowers. Humans can hand-pollinate melons, squash and cucumbers during hot spells by using a clean artist’s paint brush to move pollen from the male flowers to the female flowers. On squash, the male flowers develop first and stand on a long, slender stem. The female flowers come later to the party, bloom for one day, and have a small immature fruit at the base of the flower. On cucumbers and melons, the male flowers grow in clusters on short stems; the female flowers are single and on longer stems.
Beans, peppers and eggplants
Beans are considered a warm-season crop and our summers are hot, not warm. When temperatures are above 90 degrees, bean flowers will drop. Hot weather also stresses the bean vines as well, leading to insect infestations. Beans should be planted from seed as soon as temperatures warm in late February or early March; we can have a late-season planting of beans as well in late August. Keep the soil around beans evenly moist and pull off mature pods to promote continued flower production. If pest insects (mites, whiteflies) are a serious problem, pull out non-productive bean vines and replant another crop in late August.
Peppers and eggplants that were planted at the same time as tomatoes or cucurbits may not yet have flowers. Not to worry; peppers and eggplants hold their flowers well and produce fruit nearly constantly during the hot months of summer.
Send Elinor Teague plant questions at firstname.lastname@example.org.