How to Grow Lettuce Indoors
By Desmond Hale · June 26, 2026 · 7 min read
Quick answer
Sow loose-leaf lettuce thickly in a container at least 6 inches deep, give it 4+ hours of direct light or 12 hours under an LED, keep the mix evenly moist, and start cutting outer leaves at 4 weeks.
Choose loose-leaf, not head lettuce
Head varieties like iceberg need months and space to form. Loose-leaf types — Black Seed Simpson, Oakleaf, Salad Bowl, Red Sails — are bred for repeat cutting and work far better indoors.
Container and soil
A window box 6 inches deep and 18 inches long holds enough lettuce for a salad every few days. Use light potting mix, and make sure there are drainage holes along the base.
Sowing and thinning
- Scatter seed about an inch apart and cover with a quarter inch of mix.
- Mist daily until seedlings appear, usually in 4–7 days.
- Thin to 2–3 inches apart; eat the thinnings.
- Sow a fresh box every two weeks for continuous harvests.
Light and temperature
Lettuce is a cool-season crop and tolerates less light than fruiting vegetables. It bolts — turning bitter and sending up a flower stalk — above about 75°F, so keep it out of hot spots near radiators.
Cut-and-come-again harvesting
Take the outer leaves and leave the growing center intact. One sowing yields three to five cuttings over about six weeks before it is worth restarting.
Frequently asked questions
How much light does indoor lettuce need?
Four or more hours of direct sun, or 12 hours under a full-spectrum LED positioned 8–12 inches above the leaves.
Can lettuce grow hydroponically indoors?
Yes — lettuce is the ideal hydroponic crop and grows noticeably faster in a countertop system than in soil.
How many plants do I need for regular salads?
About 8–12 loose-leaf plants supports a salad for two people every two or three days when cut as outer leaves.
