How to Grow Lettuce Indoors

How to Grow Lettuce Indoors
  • 2-6 hours
  • Beginner
  • 150-250
What You'll Need
What You'll Need

Growing lettuce indoors is a simple process. The only special equipment required are grow lights, and those are available at most hardware stores and garden centers. The process is easy enough to be followed by a complete novice, and parents may even want to involve their children to teach them the beauty of organic gardening. Follow the simple steps outlined below, and you can have fresh lettuce in a matter of weeks.

Step 1: Prepare Grow Boxes

Some of the best containers for growing lettuce are the plastic clamshell boxes in which fresh fruit and vegetables are stored and put on display at supermarkets. Cardboard egg cartons are another great way to start plants. All you need to do for either one is to punch or cut small slits in the bottom to allow water flow, and to put about an inch of sifted potting soil in the boxes.

Step 2: Plant the Seeds

Next, you need to add the seeds. Plant approximately 25 seeds in each container. If you are using egg cartons, reduce the number of seeds to about 5 to 10 seeds per cup. When the seedlings start to grow, you can easily thin out the plants to keep the strongest ones, so don't worry about having too many seeds in the mix. Cover the seeds with about ¼-inch of soil, and spray lightly with the water.

Step 3: Adjust the Lighting

The amount of light available is important for growing lettuce seeds because it determines the speed of growth and lushness of the plants. Using electric grow lights is not absolutely necessary, but it is recommended that your new plants receive at least 10 to 12 hours of light per day. For best results, keep in mind that lettuce is a cool weather plant; keep the growing container from getting above 75 degrees. Higher growing temperatures will not harm the plants, but the temperature will have a tremendous impact on how well the lettuce is able to ball into a pronounced head.

TIP: Our expert gardening advisor Kathy Bosin adds, "Critical here is that the light needs to be placed directly over the plants--it's best to hang them off of chains that can be lifted as the plants grow. The bottom of the lights should be within 1 inch of the top of the soil or plants."

Step 4: Weed the Early Shoots

As the lettuce shoots begin to sprout, weed out the weaker plants in each container.

TIP: Kathy suggests, "Weed by pinching the stems off with your fingernails--we don't want you to pull the tiny shoots out of the soil, or they could disturb the roots of the plants you want to keep."

Step 5: Care for the Seedlings

Keep the soil moist. In as few as 7 to 10 days, you will be able to make the first leaf cuttings. By the end of the first month, your lettuce plants should be strongly rooted and you will be able to harvest the first tender shoots. By the 6th week, you will be ready to transplant the lettuce plants to more permanent containers.

TIP: Kathy adds, "It's always better to water deeply and allow soil to almost dry, than it is to keep soil constantly wet. Check to see if your soil is dry every day, but it's not necessary to water every day, every other day is usually fine."

Step 6: Transplant

Transplanting is a very simple process. Dig a small hole in the new container that is approximately the size of an individual seedling container. Take the growing box in one hand and carefully remove the entire plug of soil. Transfer the entire clump to the new container, and pack it loosely into the soil. Water lightly, and water again in 4 to 6 hours.