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Starting Lettuce Indoors

by dig the dirt editor

Starting lettuce seeds indoors has several advantages over sowing them directly in the garden.


Lettuce seedlings avoid the hazards of being outdoors in early spring, such as frost, birds, and insects. It also permits you to set out the plants at the correct spacing, which lets you skip the extensive thinning that direct-seeded lettuce often requires and enables the plants to grow quicker. In fact, iceberg types generally refuse to form a proper head at all if crowded.

Sow your seed about 8 weeks before the last frost date!  You can set out the first transplants as early as two or three weeks before your last frost. Note that the seeds germinate and grow best in cooler conditions; high soil temperatures cause them to go dormant.


  • Lettuce grows quickly, so use containers that are large enough for the young plants to reach garden size without an intermediate transplanting. Small plastic six-packs, saved from nursery purchases, are fine. Just be sure to clean them with a solution of one part bleach to nine parts water, as young seedlings are vulnerable to disease organisms.
  • Fill the containers with damp but not soggy potting mix to within a half-inch of the rim, tapping them to settle the mix. With the tip of a pencil, push two or three of the tiny lettuce seeds into each cell. Cover lightly with no more than an eighth of an inch of mix, and then firm it gently over the seeds.
  • Label with the variety name and date. Then cover the containers with plastic wrap to retain moisture and then set them in an indirectly lit spot with temperatures of about 70 degrees Fahrenheit, which is cooler than tomatoes and peppers require.




  • Start checking for sprouts three days after sowing. As soon as you see leaves, remove the plastic wrap and set the containers in a sunny south-facing window or about three inches beneath a fluorescent grow light.
  • Try to keep the seedlings at about 60 degrees during the day and 50 degrees at night. Lettuce likes it cool.
  • Water whenever the top of the mix feels dry. To avoid dislodging the small plants, mist them or place the pots in a few inches of water. Remove the flat once the surface of the mix is moist.
  • Once a week, apply a liquid fertilizer such as 5-10-5 at half strength to keep the plants healthy and strong.
  • When the seedlings have two true leaves, thin them to one plant per cell. Use small scissors to cut off the extras—pulling them out will disturb the roots of the plants you want to keep.




  • Before planting the seedlings in the garden, it’s important to acclimate them gradually to the rigors of outdoor life.
  • About 10 days before your intended transplanting date, stop fertilizing and allow the mix to become slightly drier between waterings.
  • A few days later place the plants outdoors during the day in filtered light or in a cold frame. Bring them back in at night, or cover the cold frame.
  • 'Expose them to a little more sun and cold each day. When they reach about three inches, they should be ready for the garden.




  • Lettuce thrives in well-prepared, moisture-retentive soil. Dig in several inches of compost or well-rotted manure, plus a dose of a balanced fertilizer for vegetables, applied according to the directions.
  • If possible, transplant the seedlings on an overcast, windless day to avoid dehydration.
  • Space iceberg lettuce plants one foot apart, with 18 inches between rows.
  • Other types of lettuce can be set eight inches apart with one foot between rows.
  • Water the seedlings immediately and cover the bed with a floating row cover, which will protect them from drying winds and promote growth.



indoor gardening, growing lettuce, Seed starting