When should you plant your warm season vegetables?

This weekend, May 11 and 12, the Community Garden Coalition will offer warm season plants like tomatoes and peppers to gardeners. See times and other details.

So, we thought we’d take a moment to explain why we chose a date in mid-May despite some long periods of warm weather in April.

Weather in Mid-Missouri is highly variable, as anyone who has lived here for more than a month knows! When gardening experts discuss freeze dates for our area there are two critical time periods. The first is the average frost-free date. The second is the final frost-free date.

Although these dates shift over time, a recent report by Pat Guinan the state climatologist lists April 10 as the average frost-free date for Boone County. However, local factors can impact this. For instance, valleys tend to be cooler than hilltops, and urban gardens are usually warmer than rural ones because all the concrete holds the temperature higher.

The latest frost on record in Columbia was May 9, 1906. That may seem like a long time ago, but we were close to freezing this year on April 27. We want to give our gardeners, especially eager new ones, the best chance for success. Distributing sensitive plants a little later can avoid the sad circumstance of a late frost killing everything.

Here’s what my vegetable garden looked like in preparation for the cool weather at the end of April. As an experienced gardener, I am a gambler and my heirloom tomatoes were getting too big for my indoor pots. As you can see, protecting those transplants from frost was a lot of work, and not many gardeners are up to that sort of challenge—material and time wise.

Another consideration is that many warm season plants, especially eggplant and peppers, don’t like “cold feet.” They want warm soil to send their roots into, and can become stunted and drop their flowers when temperatures dip below 50 degrees.

It’s always a guessing game to pick the optimum time to plant in mid-Missouri, but these are some of the factors we try to balance when we plan our events. Hopefully the warmer weather will hold for the rest of May and your garden will grow happily.