How Cold Can Lettuce Seedlings Tolerate? Your Guide to Growing Lettuce in Chilly Weather

Lettuce is a veggie that does best when grown in cooler, moist conditions; temperatures between 45-65 F. (7-18 C. ) are ideal. How cool is cool, though? Will frost damage lettuce plants? Read on to learn more.

Lettuce is one of my favorite crops to grow in my vegetable garden. I love being able to walk outside and pick fresh crispy lettuce leaves for salads or sandwiches. However I live in a region with cold winters, so I often wonder – how cold can lettuce seedlings tolerate?

As a cool weather crop lettuce thrives when temperatures are between 60-65°F. But lettuce plants can actually survive much colder conditions especially if you choose cold-hardy varieties. Read on for tips on growing lettuce in cold weather and how to protect your lettuce seedlings from frost.

Ideal Temperatures for Growing Lettuce

Lettuce grows best when daytime temperatures are in the 60s and nighttime temperatures are in the 40s. Temperatures above 80°F will cause lettuce to bolt and become bitter. Below 55°F, growth will slow down.

According to the University of California Cooperative Extension, lettuce seeds germinate best when soil temperatures are around 75°F. Lower soil temperatures will delay germination.

Mature lettuce plants can tolerate cold better than seedlings. With proper hardening off, most lettuce varieties can withstand temperatures as low as 20°F without damage. Certain cold-tolerant varieties can survive even lower temperatures.

Choosing Cold-Hardy Lettuce Varieties

If you live in an area with cold winters, choose lettuce varieties that are adapted to colder conditions. Good options include:

Romaine lettuces – These have great cold tolerance. Try cultivars like Winter Density, Flashy Trout Back, or Cimmaron.

Leaf lettuces – Green leaf and red leaf lettuces are also quite cold-hardy. Good options include New Red Fire, Red Sails, or Salad Bowl.
Butterhead lettuces – Opt for cultivars specifically bred for cold climates, like North Pole or Crisp Mint.
Winter lettuces – Cultivars like Rouge d’Hiver or Arctic King can withstand freezing temperatures once mature.

Growing Lettuce Successfully in Cold Weather

Here are some tips to help your lettuce thrive in chillier temperatures:

Start seeds indoors – Lettuce seeds will germinate better indoors where temperatures are warmer. Start seeds 4-6 weeks before your last spring frost date.

Use row covers – Cover seeded beds with fabric row covers to retain heat and protect from frost. Remove during the day when temps exceed 70°F.
Amend soil with compost – Rich soil holds heat better than thin soil. Incorporate 2-3 inches of compost before planting.
Use black plastic mulch – The black color absorbs heat. Lay down 1-2 weeks before planting lettuce.

Plant in protected spots – Choose locations sheltered from wind, like against a wall or fence. This prevents too much heat loss.
Harvest outer leaves – Removing outer leaves allows the plant to concentrate energy in its center. This increases cold hardiness.

Protecting Lettuce Seedlings From Frost

Lettuce seedlings are less tolerant of cold than mature plants. Follow these tips to protect tender lettuce from early spring and late fall frosts:

Cover with cloches – Use individual plastic domes, tunnels, or milk jugs to trap heat around plants. Vent during the day.
Use floating row covers – Drape lightweight fabric over plants; secure the edges with stones, boards, or garden staples.

Water before a frost – Moist soil holds more heat than dry soil. Water beds thoroughly before an expected frost.
Use cold frames – These structures have tops that let in sun and trap heat. Close lids at night to protect from frost.
Harvest all leaves – If a hard frost is expected, harvest all leaves so the plant can direct energy to its core. This improves survival.

Caring for Lettuce after Frost Damage

If lettuce leaves show frost damage, don’t panic. The plants can likely recover:

Wait 2-3 days – Frost-damaged tissue often looks worse immediately after the frost. Give it time to recover.

Remove damaged outer leaves – Prune away any leaves showing clear frost damage. New leaves should reshoot from the core.
Provide extra protection – Drape fabric row covers over damaged plants for added warmth until new growth appears.
Harvest damaged heads – If hearts are damaged, harvest immediately and replant. Outer leaves may still be usable if picked promptly.

With proper planning and care, you can grow lettuce successfully in the cold. Just choose appropriate varieties, harden plants off properly, and protect them from severe or prolonged frost. With a little extra attention, you can enjoy fresh lettuce from your garden even during chilly weather.

Does Lettuce Need to be protected from Frost?

Growing your own lettuce is a beautiful thing. It’s fun and satisfying to pick your own fresh food. Plus, lettuce will keep growing after you pick it, so you can keep getting fresh greens. But what happens when it gets close to freezing? Does your lettuce need to be protected from frost? Lettuce seedlings can usually handle a light frost and, unlike most vegetables, will keep growing through the fall when frost is a possibility in some places. Still, cold, clear nights may damage lettuce with frost, especially if the cold spell lasts for a long time.

Lettuce and Frost Resulting Symptoms

Frost damage in lettuce shows up in different ways depending on how bad the freeze was and how long it lasted. When the leaf’s outer cuticle separates from the tissue below, it’s a common sign. The dying epidermal cells give the leaf a bronzed color. When there is severe damage, the leaf veins become necrotic and spots appear on the leaf, which looks like pesticide burns or heat damage. Sometimes, the tips of young leaves die off or the edges get damaged by frost, which makes the leaf tissue thicker. Any frost damage to lettuce should be fixed right away, or the plants will start to rot and become unfit to eat.

How cold can lettuce plants tolerate?

FAQ

At what temperature should I cover my lettuce?

Even these cold-hardy greens will need some extra protection if frequently exposed to temperatures in the low 20s and teens. You can protect your cool season crops (including lettuce, which is more easily injured than other greens), by throwing a blanket or row cover over the plants.

When can I put lettuce seedlings outside?

In the spring, begin setting out lettuce plants about a month before the last frost. Lettuce grows best within a temperature range from 45 to about 80 degrees. Hot weather makes it bitter; extreme cold freezes it. When well rooted, some Bibb types such as Buttercrunch will tolerate a surprising amount of frost.

Are lettuce seedlings Hardy?

Surprisingly it is feasible, and very easy, to continue growing lettuce throughout Autumn and Winter. There are several varieties of winter lettuce available which are specifically cold hardy and able to grow in low light conditions.

What is the night time temperature range for growing lettuce?

Lettuce is adapted to cool growing conditions with the optimum temperatures for growth of 60 to 65°F. At 70 to 80°F, the plants flower and produce seed. Lettuce can tolerate a few days of temperatures from 80 to 85°F, provided that nights are cool.