QUESTION: Can I grow lettuce indoors? What growing conditions will the plants need indoors? -Ken P.
ANSWER: You can grow lettuce indoors and enjoy homegrown salad greens all year long. Lettuce should ideally get 10 to 12 hours of sunlight each day, so it grows best in a south-facing window. The spot where you grow lettuce indoors should also be free from heat sources, drafts, and the danger of interference from pets or small children. If an appropriate window isn’t available, you can still grow lettuce indoors using grow lights.
The best containers for growing lettuce indoors are flat and shallow, with good drainage, or plastic pots four to six inches in diameter with good drainage. To grow lettuce from seed, use a seed starting mix rather than potting soil or garden soil. The best lettuce varieties to grow indoors are loose-leaf types, and head lettuces should be avoided.
Fill your containers with three or four inches of moist soil, then sprinkle your lettuce seeds on top, spacing them about an inch apart. Very lightly cover the seeds with seed starting mix. Place a tray underneath your lettuce containers to catch the drainage of water, then place them in their growing location. Cover the containers with loose plastic wrap or, if a lid was provided, use the lid. This will help keep humidity high while the plants are sprouting.
Check the seeds each day, and once you see evidence of sprouting, remove the cover and thin the sprouted plants to leave an inch of space between them. Thin the plants using clean, sterilized garden shears or kitchen scissors. Young plants should be kept moist but not waterlogged; a spray bottle is a good way to water seeds and seedlings.
Begin providing your lettuce plants with fertilizer once their first true leaves appear. In three to four weeks, leaves should be about four inches long and ready to harvest as baby lettuce. Cut only the leaves you need, and the plant will keep growing so you can harvest from it again and again.