Growing lettuces in the heat of summer and all year round
By Katie Jackson
This is such an excellent time to make cool, refreshing salads with the many summer fruits and vegetables currently available from home gardens and produce stands, but don’t forget that we can also add crisp homegrown salad greens to our plates, too.
Even though lettuces and other salad greens are considered cool-season crops, a number of heat-tolerant cultivars can be grown during the summer as long as we provide them with the proper growing conditions to weather the hot weather. Plus, it’s not too early to get ready for fall salad season and establish a growing system that provides fresh salad greens all year long.
The term “salad greens” includes several different leafy greens, most of which hail from three primary botanical families. Lettuces belong to the aster or sunflower family (Asteraceae); kale, arugula and mustard greens are members of the cabbage (Brassica) family; and spinach and chard are kin to the beet and quinoa (Amaranthaceae) family. Each of these greens has their own distinctive flavor and texture qualities, from sweet and delicate to spicy and fibrous, but the easiest of them to grow this time of year are the lettuces.
Lettuces are typically grouped into four major categories: crisphead (iceberg), loose leaf, romaine (cos) and butterhead (semi-heading). Loose leaf cultivars, which includes oakleaf lettuces, are usually the most heat tolerant followed by the butterheads. Crisphead and romaine lettuces are often the hardest to grow in the heat of summer; however, a number of heat-tolerant cultivars have been developed in all four of these lettuce categories, so the options are improving.
Since lettuce seeds are relatively inexpensive and store well (in a cool, dry place), consider buying seed for lots of different cultivars. That way you can try some now and have the others ready for use into the fall and throughout the year. This time of year it may be difficult to find prepackaged lettuce seed at local nursery centers but you can order them year-round from your favorite seed supplier.
Once you’ve got seeds in hand, the biggest challenge to growing a successful late summer lettuce crop is likely going to be soil temperature. Lettuce seeds will not germinate in soil or growing media that is warmer than 80 degrees so you may want to start the seeds in growing flats that can be kept indoors or in a cool, shaded outside area until the seedlings have emerged. They can then be transplanted into the garden, which this time of year should be in an area that gets morning sun and afternoon shade.
If you don’t have such a location or if it’s especially hot outside, cover them with a light layer of mulch or a shade cloth and keep them well watered.
Another planting option that is perfect this time of year (and any time of year) is to plant lettuce in containers that can be kept outside the kitchen door or inside the house in a warm (but not directly in the sun) location. That way you can better control air and soil temperatures and you’ll have lettuce close at hand when you’re ready to harvest some for a summer meal.
In addition, lettuces and other leafy greens are pretty so they make nice, edible ornamental plants for pots and in flowerbeds throughout the year.
If you want to have a crop of lettuce growing all the time, try succession planting. Just sow new batches of seed every two to three weeks throughout the year so as one crop tapers off, a new crop of fresh greens is coming on.
As you’re exploring all the late summer/early fall lettuce options, remember that now is also the time to begin buying and starting seeds for other fall crops such as bush beans, beets, carrots, cole crops (broccoli, Brussels sprouts, cabbage, cauliflower, kale and kohlrabi), leeks, mustards, onions, peas, radishes, spinach and turnips.
If you need guidance on what to plant when, check out the Alabama Cooperative Extension System’s free Planting Guide for Home Gardening in Alabama publication, which can be found at www.aces.edu/pubs/docs/A/ANR-0063/ANR-0063.pdf or through your local Extension office.
Katie Jackson is a freelance writer and editor based in Opelika, Alabama. Contact her at firstname.lastname@example.org.