Anyone who has tried Roberta Bailey’s mixes knows that they are among the best in the business. She chooses from all the superior organically grown bronze and red varieties that we have. Sure to please, sure to dazzle.
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. Sesquiterpene lactones produced in the latex render lettuce bitter when it bolts.
Sow every 2 weeks for continuous supply. Lettuce will not head unless thinned frequently and ruthlessly to final distance of 1'. Heavy nitrogen feeders.
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.