Lettuce in garden

Lettuce comes in many varieties

In among my posts on sociohorticulture, or how people and communities relate to gardens, I’d like to share some of my tips for how to raise a home garden. This week, I’ll talk about one of my favorite cold-weather crops, lettuce.

Lettuce is a staple in the home garden.  Iceberg head lettuce, long the mainstay in supermarkets, now has competition from the many other types of lettuce. For home gardeners, iceberg lettuce is actually a poor choice compared to other varieties.  For most of us iceberg lettuce is the most difficult to grow in the home garden and takes the longest time to produce.  Most other types of lettuce grow faster, are easier to produce and are more nutritious.  These include the “loose” leaf lettuces, romaine lettuce, bibb lettuce (pictured at top) and Boston lettuce.  There are many excellent cultivars of each type and several leaf colors and textures to choose from.

Lettuce can be seeded directly in the garden or transplanted.  Grow it close together to produce microgreens or plant it about a foot apart to produce the large plants commonly offered in most markets.

In warmer climates, germination can be a problem.  In order to sprout, lettuce needs cool temperatures.  In the north lettuce can be planted in the spring, summer, and early fall, while in the south lettuce is a good crop for the fall, winter, and early spring.  When it’s too warm, lettuce seeds will go into dormancy rather than sprouting.

Lettuce spread across a plot

Varieties of lettuce seeded in a garden

Lettuce also needs light to sprout. This can be a problem if the seeds are planted too deep in the soil.  Lettuce germinates best when the seed is planted very shallowly so that it can get some light to help stimulate germination. Even a one-inch furrow would be too deep and dark for this crop.  For best results I like to make a shallow furrow about ½ inch deep for the seeds, soak the shallow furrow with water, set the seeds on the wet soil and then cover them with a thin layer of dry soil.  The thin layer of dry soil acts as a mulch, which will cause the seedlings to emerge very quickly.

In warmer climates like Texas, the fall crop of lettuce is usually planted around September-October when the soil is warm.  As a result, it often does better if it is transplanted, rather than planted directly from seed.  If the seeds go into heat dormancy in the warm weather they will not germinate for weeks or months.  Instead, I like to sow the seeds shallowly in trays, packs or pots and keep them indoors where it is cool.  There, germination usually begins in two to three days.  Once germination begins I move the seedlings outdoors so that they do not get spindly.  After 4-5 weeks in their containers outdoors, the little plants get planted in the garden soil.  There, they are planted to about the same depth that they were growing in their potting medium.

lettuce bolting

Lettuce bolting from hot-weather stress

Lettuce bolts, or goes to flower, in response to warm to hot temperatures.  This can happen at any time of the year that the temperature gets warm.  In the South this can even happen in winter.  Therefore, timing the planting date is important since even small lettuce plants can be triggered to bolt prematurely.  One way to reduce the problem is to choose slow bolt or “bolt resistant” cultivars.  All lettuce varieties will bolt in hot weather, but slow bolt varieties need a longer exposure to hot weather to trigger bolting.

Another problem that may develop in any lettuce is that it may taste bitter when it is harvested.  This is especially common if the lettuce was stressed near the harvest time, perhaps by lack of water or exposure to warm weather. There is nothing about home gardening that turns lettuce bitter.  I have been in many commercial fields of lettuce and found it to be quite bitter when it is growing in the field. And yet, when we get that same lettuce in the market it is not bitter. The trick is refrigeration.  Since commercial lettuce is chilled immediately after harvest and shipped in refrigerated trucks, it is not bitter by the time it gets to market.  The same thing will happen to homegrown lettuce that was bitter when it was harvested.  Put it in your refrigerator for several hours or a day before using it, and the bitterness will go away.