The Main Plant entry for Lettuces (Lactuca sativa)

Lettuce is a cool season crop best grown in early spring or late fall. Keep uniformly moist and cool. All or most lettuce varieties are cold hardy. Some varieties are cold hardy down to 20 degrees F if hardened off gradually before transplanting out.

Most varieties prefer cool soil temperatures for germination, e.g. 68 degrees F or cooler. Germination will occur in soil as cold as 40 degrees F, just more slowly. Most varieties have poor germination in soil above 75 degrees F.

Mulch is advantageous and reduces mud splatter. Lettuce is suitable for starting and growing in containers and/or greenhouses.

Most lettuces can't stand any heat, but some varieties have been selected to have some warmth tolerance (like Romaine). Most will become bitter and then bolt.

However, it is easy to collect seed from lettuce that will "come true" to its parents, even if grown right next to other lettuce varieties. Lettuce does not cross-pollinate (or rather, that is very, very rare). Lettuce has "perfect flowers" (self-pollinating before they open). The anthers are fused and completely surround stigma and style.

Let the best plants bolt and go to seed. Protect the seed heads from rain to prevent fungus. When many seeds seem mature, shake the seed heads into a paper bag or pillowcase every few days to collect mature seeds. Or cut the whole plant down when around half of the seeds are mature, but stand it upright indoors and let more seeds mature and dry fully. "Dry" is key! Lettuce seed will remain pretty viable for three years if stored dry.

Expect approximately 850 seeds per gram (24,000 seeds per ounce).

Sow 1/8" deep indoors in flats or small cells 3-4 wks before transplanting, 68 degrees F or cooler. They'll emerge in 3-5 days. Lettuce is hardy to light frost. If sown 4 per inch in flats, prick out after around 2 weeks and grown them on for another 2 weeks in 3/4" to 1" cells.

Or direct sow as early as soil can be worked, 1 inch apart or 3-4 seeds every 8 inches. Thin to 8 inches.
Fall: direct sow ⅛ - ¼" deep as late as six weeks before your last average frost date. Re-sow every three weeks.


Main types of lettuce:

- Looseleaf (var. crispa) Early, fast growing. Non-heading. Good for baby leaves.

- Butterhead (Buttercrunch, Bibb or Boston). Loose head with smooth or slightly oily leaves. Tender and sweet but bruises and soils easily.

- Romaine (var.longfolia) Tall, dense upright head. Tolerates warmer days before bolting.

- Iceberg (var. capitata). Difficult to grow. Will form a compact round head if weather stays cool long enough and all stress is avoided.

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Most years in spring I just buy a veggie six pack of some type of lettuce seedlings. Although lettuce is quite easily started from seed, I find I don't need very many, so the seedlings are a time saver. I do prefer to grow the looseleaf types of lettuce.

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"Lettuce (Lactuca sativa) is an annual plant of the aster or sunflower family Asteraceae.

A hardy annual, some varieties of lettuce can be overwintered even in relatively cold climates under a layer of straw, and older, heirloom varieties are often grown in cold frames. Lettuces meant for the cutting of individual leaves are generally planted straight into the garden in thick rows. Heading varieties of lettuces are commonly started in flats, then transplanted to individual spots, usually 8 to 14 inches apart, in the garden after developing several leaves. Lettuce spaced further apart receives more sunlight, which improves color and nutrient quantities in the leaves.

Lettuce grows best in full sun in loose, nitrogen-rich soils with a pH of between 6.0 and 6.8."

Taken from wikipedia's page at: https://en.wikipedia.org/wiki/...

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