A crisp salad is one of the first dishes you can enjoy out of your garden in spring. A cool-season vegetable, lettuce matures quickly. Looseleaf varieties, as opposed to those that produce heads like iceberg, are well-suited to the container garden. Lettuce continues to produce until temperatures get to warm and cause it to bolt and produce seed. You can extend the life of lettuce grown in containers as they can be moved to cooler or shadier areas of the garden come summer, helping to prevent the bolting process.
Fill an 8- to 10-inch diameter container with a moist potting mix. Leave a 1-inch space between the top of the potting mixture and the rim of the pot.
Sow the lettuce seeds on the surface of the potting mixture, following the seeding rate recommended on the package as this differs depending on lettuce variety. Generally, sow three seeds for large looseleaf varieties and six to eight seeds for small varieties. Cover the lettuce seeds with ¼ inch of soil after sowing.
Place the pots in a warm, 65 to 75 degree Fahrenheit area to germinate. Only place the containers outside for germination if temperatures above 65 F, otherwise germination can be slowed down. Water the soil as needed to keep it moist. Lettuce usually germinates within a week.
Thin the pots down once the seedlings emerge by pinching off the excess seedlings at soil level. Thin, larger varieties to one plant and small varieties down to three plants per pot. Ensure the plants are fairly equally space in the pot.
Set the container in an area that receives full sunlight and water it when the soil surface begins to feel dry. Water from the top until the excess moisture begins draining from the bottom of the pot, which ensures the soil is evenly moist throughout.
Mix 2 cups of 10-20-20 analysis fertilizer with 1 gallon of warm water. Mix 2 tbsp of this solution with 1 gallon of room-temperature water and water the lettuce with this dilute solution once per day.