Today's Paper News Sports Obits Events Classifieds Digital FAQ Newsletters

Ask a Master Gardener: When to plant lettuce seeds

by Peter Sutter | January 28, 2023 at 4:00 a.m.

According to University of Missouri Extension, it is getting time to dig out the lettuce seed.

Nice lettuce transplants can take 4-6 weeks, depending on the warmth and light level. For six weeks, one should start the seeds by Feb. 7 for the optimal planting date of March 21.

Bottom heat and supplementing with artificial light will reduce the time for producing a nice transplant. If you want to get a head start on a spring salad, now is the time to start.

Some varieties of head lettuce that do well in Mid-Missouri that you might like to try would be: Buttercrunch, Esmeralda, and Sangria.

I have grown Buttercrunch for several years. A few years ago, I tried an heirloom variety called Ice Queen and it did pretty well. I might plant one more of that this year. In the past, I mostly grew romaine and leaf lettuce but in recent years I have grown more butterhead varieties.

It is worth noting that some romaine types, like white cross, can also handle a greater fluctuation in temperature.

As with any cool weather crop, soil temperature will have some effect on the germination rate. Depending on its variety, lettuce seed can germinate when the soil temperature is 35-80 degrees.

The best soil temperature for germination is 70-75 degrees. In cooler temperatures, germination can take longer, so be patient with your early planting. Warmer temperatures (greater than 80 degrees) can lessen the germination rate of the lettuce seed.

Although lettuce plants like plenty of light, they do not like extremes of heat and can turn bitter as the season progresses, so the early plantings are the best. It is advisable to plant your later crops in a place that will be lightly shaded in the afternoon. Choose a spot that receives a minimum of four to six hours of direct, full sunlight each day.

If you want a change from planting in a row, pick an area and scatter the lettuce seeds lightly and evenly over a moist, but not soaking wet, soil surface. Scratch the surface, or lightly cover the seeds with a sprinkling of soil. Lettuce seeds, like most very small seeds, need light to germinate.

One of the best things about growing lettuce is that there are dozens of varieties available. Be sure and plant a variety of colors. I sometimes mix several leaf varieties together and plant them in the same area. Then when harvesting, I get a nice variety that looks great on the table without much effort.

Thin the plants after they reach the seedling stage by pulling out some of the seedlings to leave enough space between the remaining plants. I usually sow the seeds very thickly, which helps eliminate weeds, then as soon as the plants have a few bite-sized leaves I start to thin them out.

These small tender plants are great in salads. If you are growing the head variety and want the lettuce to develop fully grown heads, then leave 10 to 12 inches between the seedlings. Other varieties require less space so be sure to read the seed packet. Not all seeds germinate and lead to plants so plant more seeds than the number of lettuce plants you need.

In 4-6 weeks, the plants will start to mature so pick the leaf varieties often before the leaves get too big. If we happen to have a heat wave when you're ready to harvest and your crop gets a little bitter, try washing and storing the leaves in the refrigerator. The cool temperature will remove a lot of the bitterness in about 48 hours.

Peter Sutter is a lifelong gardening enthusiast and a participant in the MU Extension's Callaway County Master Gardener program. Gardening questions can be sent to [email protected].

Print Headline: Ask a Master Gardener: When to plant lettuce seeds


Sponsor Content