As temperatures rise, gardeners look to warm-season vegetables

COLUMBIA, Mo. – Home gardeners can finally put their green thumbs back to work on garden mainstays like tomatoes and peppers.

Warm-season vegetables need the milder temperatures of late April and early May to ensure successful growth from seedlings to fruitful plants. The average frost-free date—the day when the chance of a late freeze falls to 50 percent—was April 10 for southern Missouri, April 15 in central Missouri and April 20 in the northern part of the state. With each passing day, the chance of frost become lower throughout the state.

Peppers, green beans, cucumbers and eggplant are all warm-season vegetables, but many consider the true start of gardening to begin with planting tomatoes.

“The taste of homegrown tomatoes makes them America’s No. 1 home garden vegetable,” said David Trinklein, a University of Missouri Extension horticulturist. “Tomatoes and other warm-season vegetables don’t tolerate frosts, so waiting until temperatures remain above 50 degrees at night can ensure the best climate for your plants.”

While there are many varieties of tomatoes, they can be divided into two basic types: vining and bush. Vining types continue to grow at their tips throughout the season, while bush types reach a certain size and put clusters of blooms out at those branch ends. To encourage earlier, larger fruit and help prevent diseases of vining tomatoes, many gardeners stake their plants and prune them of “sucker” shoots, normally found where a leaf is attached to the main stalk.

“The purpose of pruning is to limit fruit setting,” Trinklein said. “The food reserves that the plant makes are put into fewer fruit that are larger and mature a few days earlier than unpruned plants. A few days means a lot to an avid tomato grower.”

Green beans are a garden staple that make efficient use of space.

“Bush beans are popular, but there are climbing beans that use space three-dimensionally,” Trinklein said. “Beans are a perfect succession-planting crop to follow an early crop such as spinach. Additionally, beans can be planted as a late-season crop in the same space during an ideal year.”

Sweet corn is another favorite. Early-maturing varieties of corn can give you a jump on harvesting fresh corn on the cob. These early varieties tend to better withstand the cool soil and air temperatures of spring, but they also have drawbacks.

“It takes nature a given amount of time to produce a cob of corn, so you won’t have the big, full, round ears with early-season varieties compared with those that mature in July or August. But it is still sweet corn.”

For some vegetables, it just doesn’t pay to rush. Squash, peppers, melons, pumpkin and sweet potato are among those warm-season vegetables that you should not plant until both soil and air are warm enough.

“You don’t do peppers a favor at all putting them out early, because they will not set fruit at temperatures below 55-60 degrees. Early planting risks a frost without an advantage,” Trinklein said.

Read more about vegetable types and recommendations from the MU Extension guide “Vegetable Gardening” (MG5), available online at www.extension.missouri.edu/p/MG5.