Tips for growing lettuce: Plant lettuce early — directly in the ground as soon as the soil can be worked; or start seeds indoors in cool soil. Move transplants into the garden a good month before the last frost is expected. Snow won’t hurt them, but a desiccating cold wind will. Plant them in a protected area, or use row covers.
Lettuce prefers soil that is high in humus, with plenty of compost and a steady supply of nitrogen to keep it growing fast. Use alfalfa pellets or a slow-release fertilizer.
If you live in an area where spring suddenly turns to summer, try slow-bolting lettuce varieties such as ‘Deer Tongue’ and ‘Oakleaf’. Dark-red varieties such as ‘Ruby’ and ‘Cerise’ do worse in hot weather because their red pigment absorbs more heat.
Lettuce will tell you when it needs water. Just look at it. If the leaves are wilting, sprinkle them anytime — even in the heat of the day — to cool them off and slow down the transpiration rate.
To plant a fall crop, create cool soil in August by moistening the ground and covering it with a bale of straw. A week later, the soil under the bale will be 10° F cooler than the rest of the garden. Sow a three-foot row of lettuce seeds every couple of weeks through the fall — just rotate the straw bale around the garden.