Celtuce is known also as stem lettuce, celery lettuce, and asparagus lettuce. It looks like a cross between celery and lettuce. This type of lettuce is grown for the edible enlarged seed stalk. The outer leaves resemble loose leaf lettuce, but are a lighter green. These leaves may be eaten in salads at a young tender stage. However, they become bitter and unpalatable rather quickly due to the formation of a milky sap.
Soon after the development of the outer leaves, a central stalk bearing tiny leaves at the top starts to elongate. Allowed to grow, this flower stalk will reach 4 to 5 feet in height. It acts very much like regular lettuce bolting to seed. The outer edges of the round stem contain the bitter milky sap.
When the stem is about 12 to 18 inches long, it should be cut off down into the leafy portion of the plant, being sure to peel the outer skin, removing the portion containing the bitter sap. The soft, translucent green central core is the edible part. It may be eaten fresh, either sliced or diced into a salad. The flavor is somewhat like a cucumber, yet different. In China, where it is grown in commercial quantities, the fleshy stem is cut into sections and cooked by broiling or stewing.
Celtuce should do well whenever and wherever leaf lettuce is grown successfully. Since it is a cool weather crop, it should be planted from seed in the fall, winter, and early spring, spaced at about 8 inches in the row, and treated about like regular lettuce. Many seed catalogs advertise seed for sale.
Celtuce grows better at higher temperatures than lettuce but quality is better when grown cooler. Plant the seed 1/4 inch deep in rows 18 to 24 inches apart. Thin to 2 inch spacings when the plants are 2 inches tall. When plants are tall enough to use as leaf lettuce, thin to 8 to 10 inches.
Harvest celtuce when the stems are 3/4 inch in diameter. It is the stem the plant is grown for however, the leaves may also be used whenever they are large enough. Chill the stems as soon as the leaves have been removed.