Getting fresh, locally-grown salads is a challenge during the warm months in Florida, and other places with hot, humid weather. There are actually lots of leaf vegetables which thrive in these conditions, but the majority of these tropically-adapted leaf vegetables require cooking.
Indian lettuce (Lactuca indica) is a little-known relative of common cultivated lettuce that not only tolerates our summers, but thrives during the steamy months. Most importantly, it tastes good raw, enabling us to extend the season for locally-grown salads to twelve months a year.
The leaves of Indian lettuce are a distinctive pale, whitish-green color. (One of my friends nicknamed it “zombie lettuce” for this pale appearance!). The taste is good, although not quite as good as regular lettuce, the flavor is certainly acceptable as the base of a salad. Sometimes the leaves can have a slight hint of bitterness when this plant grows in full sun or is drought-stressed. Growing in partial shade with good garden soil and regular watering can minimize or eliminate bitterness.
The growth habit of Indian lettuce is a bit different from that of the more familiar forms of lettuce. Common lettuce (Lactuca sativa) at first stays a low-growing plant with a rosette of large, succulent leaves, then it “bolts”, sending up a tall flower stalk lined with tiny, bitter leaves. Indian lettuce, on the other hand, starts sending up a stalk almost immediately, with long, strap-like leaves, and just keeps getting taller and taller, and the leaves stay large and tasty through most of this process. You just keep harvesting leaves as the stalk gets taller and taller, for many months.
At some point during its growth process, the plant starts to branch out and produce leaves that are progressively smaller and smaller, but still good to harvest. Eventually the plant can get up to six feet (two meters) of total height, although at that point it often has flopped over on its side, and the growing tip has turned upward. At around six feet of stalk height the plant starts to flower, with small, whitish-yellow blooms, and then makes tiny, black seeds.
I saw one report claiming that Indian lettuce is a perennial, but the form of this plant that I have is strictly annual: once the plants flower and set seed, their life’s mission is done, and they die.
I’ve found that starting Indian lettuce from seed can be tricky. Sometimes I’ll start a batch of seed and get virtually 100% germination, with seedlings that all rapidly grow into vigorous, healthy plants. Sometimes I’ll get very low germination rates, even as low as zero percent occasionally. And sometimes seedlings will germinate, and a few will grow rapidly, but others will lag behind and eventually die. I haven’t figured out the trick to getting reliable germination and growth. Once the plants get beyond the critical tiny seedling stage, they tend to grow rapidly.
I first got seed of Indian lettuce from the fantastic nonprofit organization ECHO in Fort Myers, Florida, around 2003, and I’ve kept it going since, saving my own seed and sharing it with some other gardeners in the Gainesville, Florida area.
I don’t know if it’s possible to hybridize Indian lettuce (Lactuca indica) with common lettuce (Lactuca sativa), but if so, this could potentially be a way to develop new varieties that combine the delicate, delicious flavor of common lettuce with the heat and humidity tolerance of Indian lettuce. Even as it is now, Indian lettuce is a valuable addition to gardens and farms in tropical and subtropical parts of the world subject to weather too hot and humid for regular lettuce to thrive.
One note of caution: I’ve read that many species in the genus Lactuca contain sap with a compound having a narcotic effect. I don’t know how much of this compound, if any, may be present in Lactuca indica, and I’ve never noticed any effects after eating this species, but it’s something to be aware of.
The name of this species is confusing. Even though both the common and botanical names of it imply that it is from India, reportedly it’s actually native to China (apparently whoever originally named it was mistaken about where it came from). Also, some people use a slightly altered form of the name, calling it “India lettuce”, to avoid confusion of people thinking this species might be associated with the native people of the Americas (it’s definitely an Asian plant).
Indian lettuce is very hard to find seed of. Unfortunately, my own supply of seed of Indian lettuce is extremely limited and I don’t have any available for sale. If you find a commercial source for seed of this species, please post it in the comments.