If you want to try growing lettuce transplants at home, you’ll need a cold frame, greenhouse, or a hotbed. In a cold frame, you’ll need about 11 weeks to grow your seedlings so that they’re ready to plant in the garden. If you use a hotbed or a greenhouse, your seedlings may mature as quickly as in a month.

Plant the seeds about 5 inches apart and as they grow you can thin them to about 2 ½ apart so that they have plenty of room to grow. Providing ample space for your seedlings also helps avoid problems with fungal diseases.

When you’re ready to transplant your lettuce, you should get it used to outside conditions. About a week before you’re ready to plant, set your plants outside a few hours, increasing the time to a full day after about 3 days. Your lettuce should be ready to plant after a week of exposure to outside temperatures. Wet down your garden beds several hours or a day before you transplant.

 

Kansas State University has an excellent site about growing lettuce and other vegetable transplants.

Harvesting your lettuce at the correct time is important for maximizing its flavor and texture. If you let your lettuce crop sit in the garden too long, it will increase in bitterness and the leaves will become tougher. Lettuce is generally ready to harvest about 80 days after planting with seeds and about 60 days after using seedlings.

If you grow romaine or butter leaf lettuce, you should first remove the outer leaves, then dig up the entire plant and cut it off at the base. This way, it’s possible to have a second crop. With leaf lettuce, simply remove the outer leaves and let the plant continue to grow. For crisphead lettuce, let the center reach full firmness before you harvest.