Usually I sow a row of lettuce seeds every 2 weeks between mid-May and late-June to assure a constant lettuce supply all summer into autumn. In episode 32 I detail how I do it. Also, below the photos are some tips on growing lettuce in the brutal summer heat. First please indulge my need to kvetch, wannabee poet style.
Too darn hot to plant seeds but,
wash most seeds away but,
1. Grow leaf lettuce varieties that can handle the mid-summer heat such as jericho, anuenue, black-seeded simpson, new fire red, radichetta, victoria and batavian nevada. Green varieties generally tend to be better. Look for 'slow-bolt' indications on the seed packets.
2. Plant the lettuce in shady parts of your garden to avoid midday sun
3. Plant lettuce in containers on a shaded porch or patio
4. Harvest lettuce leaves often and while they are young so they don't get bitter
5. Water in the morning and evening. On the brutal 90+ days give 'em a little mist frm a spray bottle.