By Amy Grant
Lettuce is a veggie that does best when grown in cooler, moist conditions; temperatures between 45-65 degrees F. are ideal. How cool is cool, though? Will frost damage lettuce plants? Read on to learn more.
Does Lettuce Need to be protected from Frost?
Growing your own lettuce is a beautiful thing. Not only is it rewarding to pick your own fresh produce, but once picked, lettuce will continue to grow, giving you successive harvests of fresh greens. But what happens when temperatures dip toward the freezing mark? Does your lettuce need to be protected from frost?
Lettuce seedlings will generally tolerate a light frost and, unlike most vegetables, continue to grow through the fall when the possibility is a probability in some regions. That said, cold, clear nights may create frost damage in lettuce. especially if the duration of the cold snap is very lengthy.
Lettuce and Frost Resulting Symptoms
Frost damage in lettuce causes a variety of symptoms relating to the severity and length of the freezing period. A very common symptom is when the outer cuticle of the leaf separates from the underlying tissue, causing a bronzed color due to the death of those epidermal cells. Very severe damage causes necrotic lesions of the leaf veins and spotting of the leaf, similar to pesticide burn or heat damage.
On occasion, the tips of young leaves are killed outright or the frost damages the edges, resulting in thickening of the leaf tissue. Any damage to lettuce due to frost should be removed or they will begin to decay, causing the entire head to become inedible.
Lettuce and Frost Protection
Lettuce is tolerant of cold temperatures for short periods of time, although the plants’ growth will slow down. To protect lettuce in frost prone areas, plant romaine or butterhead lettuce since they are the most tolerant of cold temperatures. If you already have a variety of lettuces growing, pick other types prior to the romaine and butterhead if you are concerned about imminent frost.
When frost warnings are reported on the weather forecast, cover the garden with sheets or towels to engender some protection. This will help in the short term, but if prolonged frost is due, the life of your lettuce is likely in jeopardy.
Finally, outdoor freezes may not be the only concern for lettuce and frost. Frosty conditions in your refrigerator will definitely damage the tender lettuce greens, leaving you with a slimy mess. Obviously, do not put lettuce in the freezer and adjust the setting of your fridge if it is prone to frosting up.