Because lettuce is a cool-weather crop, it can handle some frost. However, extended exposure to freezing temperatures can damage the plant if not protected. In many growing climates, gardeners can grow lettuce in the spring and fall. Some of these areas are at risk of freezing or frost as their lettuce plants start out or reach the end of their life cycle, depending on the season. Due to this, many gardeners want to know how to keep lettuce from freezing.
If lettuce plants are at risk of an extended period of freezing or frost, it’s important to protect the plant to prevent damage. Methods to keep lettuce safe from freezing include planting cold-tolerant varieties, covering the plants with sheets or towels, moving plants indoors, watering during the warmth of the day, and harvesting early.
Read on to learn more about caring for your lettuce crop in freezing temperatures.
Methods To Protect Lettuce Crop From Frost or Freezing
No one likes frozen lettuce plants that end up wilting and not making it past the seedling stage. Here’s a couple of proven methods to protect your lettuce plant.
Cover With Sheets Or Towels
One of the quickest and easiest ways to protect lettuce from a hard freeze is to cover the plants with an old sheet or lightweight towel. It’s best to avoid heavy-weight fabric to avoid weighing down the plants. However, lightweight fabric can create a barrier of warmth, protecting the lettuce from freezing.
As an avid gardener living in a seasonal climate, I recycle bed sheets that are past their prime to the gardening shed just for this purpose.
Hoop houses can be purchased or built using PVC pipes and sheets of plastic. These structures act as a temporary greenhouse when temperatures are too cold for lettuce or other crops.
They are ideal for larger gardening setups that may require too much coverage for old sheets. Plants can overheat in hoop houses, so it’s essential to not set them up until later in the day and remove them in the morning so your crop can breathe.
If your lettuce plants are in pots and your indoor space allows, it may be most beneficial to move lettuce or other smaller plant varieties indoors before an anticipated freeze. If the weather requires plants to be indoors for an extended time, it’s important to have a solid light source near a well-lit window or with grow lights.
When freezing temperatures are expected, water lettuce and other plants earlier in the day than when temperatures are hot. If the plants are still wet when the sun goes down, this can promote freezing, even when covered by sheets or hoop houses. Try to water the soil and roots as much as possible, avoiding the lettuce leaves, and provide enough time for any moisture that does hit the leaves to dry out before sundown.
In some growing climates growing a fall lettuce crop can be a gamble. Sometimes autumn is short-lived, and freezing temperatures come on too quickly for an abundant harvest. If growing lettuce in the fall and a long cold snap is in the forecast, it might be best to make the call and harvest what you have rather than risk losing the crop to a hard frost.
Plant Cold Tolerant Varieties
While lettuce is already a fairly cold tolerant plant, some varieties can withstand colder temperatures than others. Some of these varieties are temperature tolerant overall and can withstand hotter conditions. The most commonly known cold-tolerant lettuce varieties are Romaine and Butterhead. However, several Loose Leaf varieties can survive freezing temperatures.
Loose Leaf lettuce varieties tend to be easier to grow than Romaine and Butterheads, with Romaine being the most challenging of the three. Loose Leaf lettuce varieties are what I prefer to grow because you can harvest leaves regularly throughout the growing season rather than waiting on one final harvest. Some Loose Leaf lettuce varieties that are hardier to cold weather include Grand Rapids, Salad Bowl, Green Forest, and Drunken Woman.
Butterhead or Bibb lettuce varieties are also reasonably easy to grow. The plant’s leaves grow in a lovely roselike pattern with growing similarities to Loose Leaf and head lettuce varieties. Leaves grow more tightly with Butterhead varieties but are still somewhat loose and can be harvested throughout its growth, not just at the end as with head lettuce.
Some Butterhead varieties will form a small lettuce head at the core of the rosette of leaves that can be harvested and eaten towards the end of the lettuce’s life. Butterhead varieties that are cold and frost-hardy include Winter Marvel, Esmeralda, and North Pole.
Romaine lettuce varieties are typically categorized as heads of lettuce. However, most of Romaine’s leaves are more open than other head lettuce varieties.
Romaine leaves are crisper than Loose Leaf and Butterhead varieties, making them more challenging to grow. In addition to being cold-tolerant, many Romaine varieties are also heat tolerant. Some Romaine varieties that do well in frosty weather are Frisco, Winter Wonderland, and Little Gem.
Lowest Temperatures Lettuce Can Withstand
While some lettuce varieties may not be considered “frost hardy,” all are frost-tolerant. Frost-tolerant plants can handle some frost and short-term temperatures as low as 28 degrees Fahrenheit. Depending on the plant hardiness zone in which you live, you may be able to grow lettuce in any of the four seasons.
Many areas in the United States allow for a spring and fall lettuce crop, and temperate growing zones like the Pacific Northwest allow for lettuce gardening year-round. Knowing your plant hardiness zone and following a planting and growing schedule designed for the said zone is ideal for healthy lettuce plants.
Signs of Lettuce Frost Damage & Recovery
If freezing temperatures have damaged your lettuce crop, it is most noticeable on the outermost leaves of the plant. The edges of those leaves may appear lighter and wilted compared to the healthier leaves if damaged by frost. In extreme cases of freezing, the lettuce leaves may shrivel up and disintegrate to the touch. Most often, lettuce that has suffered some frost damage is still edible within those outer-wilted leaves.
If you find that your lettuce crop has frozen or been exposed to more than a light frost, it’s crucial to get light and warmth to those plants immediately. If grown in containers moving lettuce plants to a sunny, south-facing area to dry out and warm up will help bring those plants back to health.
If freezing conditions are expected to continue, then following the previous steps to protect your lettuce crop is most important. Some lettuce varieties may take longer to bounce back after prolonged freezes, and in the more extreme cases, they may be beyond recovery. Paying attention to your geographical area’s weather patterns and having a frost plan is most important in avoiding freeze damage to your lettuce.
Final Tips on Lettuce Care
Lettuce is diverse in varieties and is one of the most enjoyable plants to grow for some. Every gardener loves a homegrown salad in the center of the dinner table. Providing a cool, somewhat shaded environment with plenty of water and well-drained soil will only add to your lettuce crop’s success.
Knowing and following the care instructions for the variety of lettuce you’ve chosen to grow is imperative. In addition, always remember to follow the guidelines for which lettuce varieties grow best in your geographical area. Sticking to these tips, as well as what is shared previously in this article, should help you reach at least one, if not a few, abundant lettuce harvests each year.
Hi there, my name is Allie and welcome to my blog; GareningWithAllie!
Much of what you see written here is just our personal experiences with gardening. Along with the content I write here, there is also a unique collection of gardening topics covered by some of our close friends. I hope you find everything you read here to be helpful, informative, and something that can make your gardening journey the most lovely experience ever! With that said, Happy Gardening!