Lettuce can be harvested year round. It prefers partial shade in the hot summer months. It can be planted directly from seed or from transplants. The wide array of colors and textures make lettuce a beautiful container crop. Plant closely for salad mixes, or spaced apart for heads. Lettuce can even be grown indoors!
Lettuce needs at least 5 hours of direct sun to produce full heads. Leaf lettuce can produce in partial shade. In the peak of summer, shade lettuce during the hottest parts of the day. Lettuce prefers rich, well‐drained soil. Mix 1‐3” of composted manure into planting area. Also mix an all purpose granular fertilizer into the bottom of each planting row.
Start early crops indoors mid‐March, about 3‐4 weeks before the last frost. Harden off seedlings when they are 1‐2” tall or 3‐4 days before planting outdoors. Seeds and transplants can go directly in the ground mid‐ April through early October. Plant a new crop ever 3‐4 weeks for a continual fresh lettuce harvest. Focus on heat resistant varieties June and July and cold tolerant varieties August and September.
Winter lettuce needs to be protected by cold frames or cloches. Lettuce can be grown indoors any time of year.
Plant seeds 1/8” deep, in rows 16‐18” apart. For heads of lettuce, thin seedlings 10‐16” apart after 2‐3 sets of true leaves appear. Transplants should be planted 10‐14” apart for loose leaf varieties and 12‐16” apart for Romaine and iceberg types. Water in new starts with liquid seaweed or B1.
Lettuce grows extremely well in containers at least 6” deep. In the heat of summer, keep lettuce containers in partial shade and water daily.
How much water your plants will require depends on the soil and weather. Lettuce loves water and will become bitter if it dries out. Water when the top 1” of soil is dry. Mulch with a 1⁄2” layer of compost to retain moisture and prevent over heating. Drip irrigation is the best way to provide even moisture and while avoiding disease issues. However, in extremely hot weather overhead sprinklers can help cool the plants and prevent bolting.
Side dress rows with an all purpose fertilizer 2‐3 weeks after planting. Or apply a foliar spray of compost tea or fish emulsion every 2 weeks until plants are 4” tall.
Lettuce can be harvested in entire heads or by the leaf. All lettuce is best harvested in the coolest parts of the day. Heads of lettuce can be cut just above soil level once the heads form. Loose leaf lettuce can be picked as soon as the leaves are big enough.
Pick a few of the outer leaves at the base leaving the center of the plant intact. Baby lettuce and salad mixes can be harvested using the cut‐and‐come‐again method. Hold a handful of leaves and cut them 3⁄4” from the soil line. You should have a new flush of lettuce in 3‐4 weeks.
It is best to harvest lettuce as you need it. Heads of lettuce will keep in the refrigerator for up to a week. Loose leaves will keep for only a few days.