Lactuca sativa 1 gram packet sows 25 ft; 2 grams, 50 ft; 1 oz, 500–700 ft. Varieties average 875 seeds/1g pkt, or 1,750 seeds/2g packet. All lettuce is open-pollinated.
Culture: May be started indoors in March and at regular intervals thereafter, or sowed outdoors as soon as ground can be worked. Many varieties won’t germinate in soil temperatures above 75° and most shut down above 80°. Where available, we present data here from a California germination experiment at 84°.
Hardy. All save icebergs tolerate heavy frost. Grow best in cool weather with ample moisture, many kinds suffer bottom rot and tipburn in heat; select summer varieties carefully. Use shade cloth to keep summer lettuce tender and sweet longer. Sow every 2 weeks for continuous supply. Lettuce will not head unless thinned frequently and ruthlessly to final distance of 1'. Heavy nitrogen feeders.
Look for the snowflake symbol after each cultivar description for indication that a variety is hardy through at least a part of our Maine winter.
Minimum germination soil temperature 35°, optimal range 40-80°, optimal temperatures 70-75°, emergence takes 15 days at 41°, 7 days at 50°, 3 days at 68°, 99% normal seedlings at 77° but only 12% normal at 86°.
Days to maturity are from direct seeding.
- BOR: Bottom Rot
- DM: Downy Mildew
- LMV: Lettuce Mosaic Virus
- PM: Powdery Mildew
- SC: Sclerotinia
- TB: Tipburn
- X: Xanthemonas
Pest: Aster Leafhopper (vector for Aster Yellows disease)
Cultural controls: control perennial broadleaf weeds near lettuce plantings, plow lettuce fields immediately after harvest.
Cultural controls: avoid mulch or nearby grassy areas.
Material (see OGS catalog
): Sluggo (8911-6
Disease: Bottom Rot
Cultural controls: rotate with grass-family green manures, plant in well-drained soil or on raised beds, more upright varieties escape infection.
Diseases: Downy Mildew, Grey Mold, White Mold
Cultural controls: rotation, reduce duration of leaf wetness, plant parallel to prevailing winds, use wide spacing, control weeds, use well-drained fields in spring and fall.
Material: Actinovate (8851
Batavians have good hot-weather germination, and excellent heat & cold tolerance.