Subtract 10–14 days for late spring or early summer, warm weather transplanting. DAYS TO MATURITY: From date of cool weather, spring transplanting. MT0 SEEDS: A variety's description followed by "MT0-30" indicates that the seed offered for sale has been tested for the presence of Lettuce Mosaic Virus and that no LMV was found in a sample of at least 30,000 seeds. For one-cut types, extend season in cold weather by holding cut heads in cooler up to two weeks to process into salad mix. Head Lettuce: Keep 14–20 days, less for delicate types like butterhead and oakleaf, and longer for lettuce grown slowly in cooler temperatures. Grow several varieties with different maturity dates for a continuous supply.
STORAGE: Keep cold at 35–40☏ (1–4☌) with high humidity but free of standing water. Make succession plantings every week or two. Remove harvest debris to improve regrowth quality. Baby Leaf: Harvest about 1" above the growing point when leaves reach desired harvestable length, about 3–4" long. Wash off sap and cool immediately to prevent staining and dehydration. Pack heads in layers facing cut ends away. Lettuce seed and transplants should be watered frequently the first 2 weeks to keep the seed bed moist but not waterlogged. Consider cutting alternating plants to extend harvest window, allowing remaining plants to continue to grow. HARVEST: Head Lettuce: Cut at base, keeping wrapper leaves for handling loss. Lift the lettuce seedlings from the seed tray and place them into the holes. Dig holes in rows 16 inches (40.6 cm) apart, just deep enough to plant the root balls underground. Dry soil must be watered to ensure coolness and moisture for uniform germination. The earliest you can transplant your seedlings is two weeks before the last spring frost date. Sow 4–6 seeds/inch in rows at least 2" apart. DIRECT SEEDING for BABY LEAF: Seeds can germinate well in soils as low as 40☏ (4☌) but often poorly above 75☏ (24☌). Transplant iceberg, romaine, and butterhead lettuce 10–12" apart in rows 15–18" apart, other types 8–10" apart in rows 12–18", and mini heads as close as 6" in a grid. Young plants properly hardened at least 3–5 days before planting can survive temperatures as low as 20☏ (-6☌). If necessary, utilize shade and frequent misting to keep trays cooled below 75☏ (25☌) during germination. TRANSPLANTING for HEAD LETTUCE: 3–4 weeks before field planting, sow in 128-cell trays barely covered with vermiculite or fine soil. The priming process in pelleted lettuce seeds broadens the temperature range in which the seeds will germinate, overcoming some of their thermal dormancy. Either follow the recommended plant spacing when transplanting (refer to the Lettuce Planting Guide, Table 2) or scatter seeds (broadcast) in a 2-inch-wide. Optimum germination results at soil temperatures of 60-68☏ (16-20☌). THERMAL DORMANCY: Lettuce seed can enter thermal dormancy when exposed to high temperatures.
Sow every 2–3 weeks for a continuous supply of either full heads or salad mix. It grows best at 60–65☏ (16–18☌) and germinates best below 70☏ (21☌), so careful variety selection is key for success in hotter weather. SCIENTIFIC NAME: Lactuca sativa CULTURE: Lettuce is a hardy, cool-weather crop and can be planted with your earliest worked soil.