While it is too early to plant tomatoes, now is the perfect time to plant lettuce. The key to growing a successful crop is to plant and mature the lettuce in cool weather. Lettuce is an annual plant that will bolt (produce a flower stalk) and become bitter when temperatures stay above 70 F.
Iceberg, or more correctly called crisp head type lettuce, used to predominate produce shelves at most grocery stores. Crisp head cultivars require a fairly long, cool growing season of 70-85 days. Indiana’s cool season is usually much too short to produce the crisp head types.
But, in recent years, the more nutritious, leaf-type lettuces have gained in popularity. Most leaf types require only half the growing time, generally, from 40-50 days. Leaf lettuce produces a loose arrangement of leaves on the stalk. Leaves may be green, such as the cultivars Black-Seeded Simpson, Green Ice, and Grand Rapids, or red, as in Ruby, Lolla Rossa, and Red Sails. For a uniquely shaped lettuce, try Oak Leaf, which comes in both green and red leaf forms. Leaf lettuce can be cut whenever the leaves are large enough to use. You can harvest just a few leaves at a time and allow the plants to keep producing more leaves or harvest the entire plant.
There are other non-crisp head types of lettuce that can also be grown successfully in Indiana. Some cultivars produce a loose head, often called butterhead-type lettuce. Butterhead types tend to have very soft, pliable leaves that have a delicate texture and flavor. Bibb, Boston and Buttercrunch are just a few examples and, in general, take 60-70 days from seed to harvest. Using transplants, instead of directly seeding into the garden, will get the plants off to a head start before warm weather arrives.
Cos or romaine type lettuce forms elongated, stiff leaves that make an upright, loose head. Paris Island and Paris White are common Cos cultivars and need about 70-75 days to mature. As with butterhead types, transplanting is recommended.
As temperatures get warm, lettuce begins to bolt, and the leaves develop a bitter flavor. It’s best to pull up and discard bolted plants and replace them with a warm season crop.
If you’ve missed out on planting lettuce this spring, don’t dismay. Leaf lettuce makes an excellent planting for a fall crop. Plant seeds in late August or early September to allow sufficient time to harvest a crop before killing temperatures arrive.