What it needs & gives back
↓ Needs
↑ Gives back
Companions
Chives
Chives can help deter aphids.
Carrot
Carrots can benefit from the shade provided by lettuce, and lettuce can benefit from the soil aeration provided by carrots.
Onion
Onions can deter some pests of lettuce.
Radish
Radishes grow quickly and can be harvested before lettuce needs the space.
Cilantro
Provides light shade for lettuce in hot weather.
Hamburg Parsley
Provides shade and can improve growth.
Leek
Leeks can be interplanted with lettuce.
Dill
Dill is a good companion for lettuce, potentially improving its growth.
Chervil
Chervil is said to improve the flavor and growth of lettuce.
French tarragon
Improves growth and flavor of lettuce.
Through the year
Emergence
Lettuce seeds germinate when soil temperatures are consistently above 5C.
Flowering
Flowering is typically induced by long days and warm temperatures, leading to bolting.
Harvest
Harvest can begin when leaves are large enough, typically 45-75 days after emergence, depending on variety and desired size.
Senescence
Plants senesce after flowering and seed set, often accelerated by hot, long days.
Timing is relative to your local season (temperate Northern Hemisphere).