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Over the Garden Fence

Hot weather in the vegetable garden

The prolonged hot, dry weather pattern has created some vegetable gardening challenges. Garden plants (and all other kinds of plants) respond to the weather conditions by adjusting vegetative (foliage) and reproductive (fruiting) growth.

Vegetable plants respond to environmental conditions. When it is too hot for us, we go inside to the air conditioning or move into a shady spot in the yard. Our vegetables are out there in the full sun, so if it is too hot and dry, tomatoes and peppers will abort any unopened flowers until better weather conditions return. This protects the plant from attempting to fulfill a fruit when water is lacking and maintaining itself under better conditions.

Right now, as our vegetables are moving from the general growth stage to producing flowers and fruits and seed pods. A consistent level of soil moisture is critical for health and for harvesting high quality, nutritious fruits and pods. Cucumbers, for example, will go from a pollinated flower to a harvestable fruit in about a seven day period. If soil moisture is lacking at any point, you find yourself with cucumbers that appear normal on one end and taper down on the other and can be bitter tasting. If you’re going for a larger, longer cucumber, the fruit may appear “fat-skinny-fat as the available water has changed. Snap bean pods will have a similar reaction to a lack of available soil moisture. We expect a nice full bean about 4 to 6 inches long with seeds inside just pushing at the bean pod wall. What we get is like those cucumbers. While not a fruiting vegetable, our lettuces will not be able to grow as rapidly as expected and the lettuce leaves will not have that expected tenderness. Another vegetable that can disappoint us during hot dry weather are the onions, especially if growing bulb onions. If at any time during bulb growth and expansion, the onion does not receive enough water, bulb growth stops at that point. Even if we water or it rains, the bulb with not continue with expansion.

So we are not disappointed in the productivity of our vegetable gardens, here is a list of critical dry periods for some of our favorite vegetables:

  • Crucifers: head development

  • Sweet corn: silking, tasseling and ear fill

  • Cucurbits: fruit development

  • Tomatoes and peppers: fruit development

  • Beans: flowering through pod fill

For some of your vegetables, like the cabbage family and sweet corn, you only have one chance to get something worth harvesting and eating. Others like cucumbers, melons, squash, beans, tomatoes and peppers will hesitate until better growing conditions return, yet you do get harvestable produce at other times.

Have more questions? Learn how to contact your local Master Gardener Help Desk in DuPage, Kane and Kendall counties, or find your local county's information online.

About the author: Richard Hentschel’s expertise extends across several subject areas with specialties in lawn care, fruit tree production, woody ornamentals, and home and community gardening. During his 45-year career in horticulture and agriculture, Hentschel became a well-known and respected expert for commercial and homeowner audiences, industry organizations, and media. He retired from University of Illinois Extension in April 2022 with nearly 30 years of service as a Horticulture Specialist and Educator in northern Illinois.