The holidays are history, seed catalogs are piled in a basket next to a comfortable chair by the fire and I’m looking for lettuce to grow indoors.
The quality of grocery store lettuce reaches its low in the dead of winter. Half-rotted, tasteless leaves and astronomical prices are prompting me to grow a decent salad indoors, because of the foot of snow on the ground and sub-zero temperatures.
I usually start Bibb and Romaine seeds under lights in early March and set out seedlings in pots and beds when days warm and nights stay in the 20’s. But this year I’m starting seeds as soon as they arrive from various catalog sources.
Growing lettuce under lights is easy. All you need are flats or shallow pots filled with potting mix, slow-release fertilizer and a light source. A south-facing window with supplemental light works, but plants will be leggy. Grow lights are the best, but if you use a shop light fixture with two fluorescent bulbs, you’ll save big bucks. The fixture and two bulbs come in at under $20 versus $75 or more for grow lights. Shop light fixtures are 48 inches long, but you
can find some that are 36 inches in length.
I suspend the fixture on chains from ceiling hooks in my sunroom. You can do this any place where the temperature stays between 50ºF and 70ºF, including basements. Lettuce grows best in cooler temperatures, so avoid areas near heat vents that blast hot air.
If you don’t want to use chains and hooks, stack books or bricks in two piles and use them as pillars on which to suspend the light fixture. Because plants grown indoors need about 16 hours of light daily, plug the fixture into a timer.
Fill containers with potting mix, scratch fertilizer into the top two inches of the mix and then space seeds across the surface. Press so they make contact with the mix. Lettuce needs light to germinate, so don’t bury the seeds.
Place containers under lights and adjust so lights are about two inches above containers. As seeds germinate and seedlings grow tall, adjust lights upward so that they are about two to three inches above plant tops. Keep containers watered; spray water on the container surface to keep seeds hydrated until they sprout. Add diluted water-soluble fertilizer to the water weekly.
You should be harvesting your first salad within 35 to 40 days. Pick outer leaves only so that plant crowns or centers will produce more leaves.
Suggested Lettuces for Indoors
- Baby Oakleaf
- Lollo Rosa
- Tom Thumb
- Garden Babies
- Red Deer Tongue
- Black-Seeded Simpson
- Salad Bowl
- Any salad lettuce mix
Doreen Howard has written for The Old Farmer's Almanac All-Seasons Garden Guide for 15 years and is the former garden editor at Woman’s Day as well as a photographer. She has grown more than 300 varieties of heirloom edibles and flowers in the last two decades.