Days to germination: 2 to 12 days
Days to harvest: 30 to 50 days
Light requirements: Full sun, with shade in the heat
Water requirements: Regular watering
Soil: Rich and well-drained
Lettuce comes in roughly 2 main types: leaf lettuce and head lettuce. Leaf lettuce is loosely bunched and you often pick the outer leaves for use without harvesting the entire head, whereas head lettuce is tightly packed and used as a whole.
You can find dozens of lettuce varieties with mixture of textures and colors. Cimmaron is a romaine type of lettuce with red leaves, and Merlot is a variety that is deep purple. Lettuce like Salad Bowl has frilly but crisp leaves.
Depending on the type of lettuce, the leaves can be packed with vitamin A, C, K and folic acid. Minerals like manganese and potassium are also found in lettuce. Darker leafed lettuce tends to have more vitamins.
Lettuce is one of the few garden vegetables that is almost exclusively eaten raw. It’s a favorite in salads and it’s enjoyed through the summer.
Starting from Seed
For eager gardeners who want their lettuce early, you can start your seeds indoors. You can start them out about 6 weeks before the last frost date, and they germinate best in cooler temperatures so don’t overheat your seed trays.
Lettuce produces very shallow roots, so your seedling pots needn’t be too deep. The seeds should only be lightly covered with soil, or even just left on the surface. They germinate best with a little light.
You can put your seedlings out into the garden about 3 to 4 weeks before your frost date. Choose a spot that will get plenty of sun, but will get a bit of shade during the hottest parts of the day.
To protect your little plants from the shock of cool spring weather, you should “harden them off” by putting their pots outside during the day for 3 days before your planting date. Bring them back in during the night.
Your garden soil should be well-drained but you don’t really need to dig it up very deeply before putting in your seedlings because of the shallow roots. Add some compost and lime to the soil while you’re at it. Space your seedlings between 8 and 12 inches apart.
If you’ve decided to plant your seeds directly in the garden, you should space them out the same distance. Seeds can go out around the same time as you would put out transplants, about 3 weeks before that last frost date. Don’t cover the seeds with much soil.
Lettuce is a typical spring crop, but you can also plant a fall crop if you want to take advantage of the cool autumn weather. Put in another batch of seeds after the hot weather has passed, allowing enough time for the lettuce to mature before frost hits again (anywhere from a month to a month and a half).
While your lettuce is growing, make sure to water consistently. It’s a very trouble-free kind of plant to grow that doesn’t require a lot of attention except to check for insects and watch for maturity.
If your lettuce starts to wilt during the day, you may need to shade the plants from the heat. Temporary covers can help keep your plants from getting too hot.
Lettuce grows exceptionally well in containers given its small size and shallow roots. Depending on the size of your container, you could grow several heads in each but one head per pot is ideal even for the smallest gardens. Some varieties of lettuce are quite ornamental, especially those with dark green or purple leaves. You could easily plant them in with your flowers.
Mix a little lime in with your soil, and water often to keep your plants from drying right out.
Pests and Diseases
One of the biggest problems with lettuce is slugs. They love to eat the tender leaves, and can be hard to spot especially with lettuce that forms a tight center. There are many home-made remedies for slug infestations, such as beer traps. A shallow saucer with beer will attract slugs during the night, and they will drown in the liquid.
Diatomaceous earth (DE) works very well to repel slugs, as well as a number of other insect pests. It’s finely crushed diatom shells and looks like flour. It’s completely harmless to people and animals, but the tiny shells are sharp enough to cut insects and soft-bodied pests like slugs. Sprinkle a good layer of it in the soil around your lettuce, and reapply after a rain storm.
Cutworms can also attack your lettuce plants. They come out in the late evening, and you can pick them off by hand if you go check your garden around twilight. They are fairly plain black caterpillars. Keep the soil around your plants tilled to keep them from taking up residence around your plants during the day. Insecticides may help if the worms are small. Big ones aren’t bothered by most sprays. They can live in nearby weeds, so don’t plant your lettuce at the edge of your garden near any “wild” areas of your yard.
If you find the tips of your lettuce leaves turning brown, its probably tip burn. It can also be caused by a lack of water, so if you’ve not been watering your lettuce, that could be it. Otherwise, tip burn is a result of calcium deficiency. Mix more lime into the soil to help correct the problem.
Harvest and Storage
Harvesting times can really vary, and it also depends on whether you intend to take the entire head at once or just pick a few leaves at a time.
If you’ve planted lettuce that grows a fairly tight head, and it referred to as a “head lettuce” then you should wait until full maturity for harvest. Then cut the head off under the lettuce, right at ground level.
Any looseleaf or romaine lettuce can be harvested much sooner than maturity if you want to just pick a few leaves at a time. In this case, you can usually start plucking leaves when the plant is about half-way to full maturity. If you prefer, you can still harvest leaf lettuce as a complete head when the plant is ready.
After you harvest, expect to find insects in among the leaves. Wash your lettuce thoroughly before use. It doesn’t stay fresh for very long, so plan on using it up quickly. There is no way to store lettuce for later use.
Once the warm weather set in, your plants are going to stop making leaves and will produce a tall stalk (in other words, they “bolt”). Once that happens, your plants are finished producing. If you’ve put in a fall planting, you can usually keep harvesting lettuce right up until the first frost.