Lettuce is a hardy annual that can tolerate light frosts and can be easily grown from seed or transplants. Lettuce need sunny locations early but can tolerate some shade and as the days get warmer, more shade is better. Sunlight combined with warm summer temperatures usually make the lettuce bitter. Lettuce grow best when the day temperatures are between 60-70 degrees F and when planted in well-drained soil that is kept evening moist with light watering.
Leaf lettuce is the most popular type of lettuce grown by gardeners, but you can also grow iceberg, butterhead, and romaine lettuce.
Sow leaf lettuce in rows with 10-20 seeds per foot and space rows about 12” apart. Thin out seedlings after sprouting to a spacing of 6” apart. If transplanting, plant individual plants 6” apart. For head lettuce plant 12-18” apart. Lettuce can be planted in between other crops that shade the lettuce during the heat of the day.
Lettuce has shallow roots so cultivate or hoe shallow to keep the weeds down. Overwatering can cause disease problems, and any overhead watering should be done in the morning to allow the foliage time to dry. Mulching is also beneficial since it keeps the leaves off the ground and the soil cool.
Generally, lettuce should be planted and enjoyed in the spring then abandoned when the it gets hot and the taste gets bitter.
Lettuce mature between 40-80 days depending on the variety.
Harvest leaf lettuce when the plants reach 5-6” tall. Harvest the older outer leaves first. Harvest bibb lettuce when the leaves begin to cup inward. Harvest romaine lettuce when when the leaves have overlapped and formed a tight head that is about 4” wide and 6” tall. Crisphead lettuce is ready to harvest when a head is formed that looks like head lettuce in the grocery store.
Click here for more information on growing lettuce from the University of Arkansas Cooperative Extension Office.