15 Heat-Tolerant Lettuce Varieties to Grow All Summer
Leafy lettuce tastes great until it doesn’t! Hot weather forces these tender crops to bolt. They sprout flowers and their leaves turn bitter. One solution is to grow heat-tolerant lettuce varieties. Seasoned grower Jerad Bryant shares 15 favorites that excel from late spring through summer.
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Lettuce is an annual crop that bolts according to temperatures, day lengths, and soil conditions. As the weather warms and the soil dries, the lettuce plants respond by growing tall flowering stalks. This response is a survival strategy known as bolting.
Bolting directs energy from leaf production into flower and seed production. The plants suck nutrients and energy from the leaves, turning them bitter in the process. You may let a few lettuce plants bolt to save seeds; otherwise, you’ll want your crops to stay leafy throughout the season.
When looking for lettuce types that’ll thrive in the summer, search for bolt- or heat-resistant varieties. Either term indicates varieties that resist bolting and grow well in hot climates. In the warmest regions, try growing these leafy greens in partial shade with consistent moisture to help prevent bolting.
Start with one or a few of these 15 heat-tolerant lettuce varieties. They’ll grow all summer!
‘Black Seeded Simpson’
Leaf lettuces grow individual leaves for fresh eating, though they also form loose heads later in the growing season. Harvest them by picking their outer foliage and letting the rest of the plants regrow. Or, cut the heads off two inches above the base and let them resprout for a second harvest.
Many leafy cultivars exist, though a few special types resist bolting in summer. ‘Black Seeded Simpson’ is one such cultivar with frilly, green foliage that forms a loose head as it matures. The small leaves are ready to eat as baby greens a few weeks after planting, and full-size ones appear after a month or more of growth.
This cultivar is heat-resistant and tolerant of light frosts. In temperate zones, grow it from spring through fall, or as a winter crop in frost-free regions.
‘New Red Fire’
Cultivars with burgundy foliage are my favorites, as they’re incredibly ornamental in the vegetable garden. Curly, wrinkly red lettuces stand out from other leafy greens. ‘New Red Fire’ is one such cultivar with maroon leaf tips and green bases. They’re frilly, fringed, and form a loose head perfect for salads, wraps, and sandwiches.
This loose-leaf variety is perfect for gardens with long, warm seasons. It’s resistant to afflictions like downy mildew, rot, and tip burn, making it an ideal choice in poor growing sites with hot weather.
‘Red Sails’
A major reason to grow lettuce is to cultivate types you can’t find at the grocery store. ‘Red Sails’ is one such variety that’s difficult to source at markets and stores. It sprouts wrinkly, red leaves in tight bunches. Chop baby greens after a few weeks, or let the plants mature into large heads for six weeks.
‘Red Sails’ sprouts buttery, tender foliage that’s great tasting no matter how hot the weather gets. Grow it in partial shade during the middle of summer, or grant it full sun in early spring and fall when the weather is cool, mild, and moist.
‘Paradai’
Sometimes, studies are necessary to help us gardeners understand which lettuces perform best during hot days! One such experiment from the Fair Oaks Horticulture Center in Sacramento proved that specific lettuces thrive despite warm temperatures and intense sunlight.
The experiment applied anti-bolting cultivation techniques on bolt-resistant varieties and then tested the results. They found that ‘Paradai’ was one of the best varieties for hot zones. Transplants planted on June 1st lasted 60 days before they grew flowering stalks. ‘Paradai’ is also gorgeous, with red oak-like leaves that form loose bunches.
Though ‘Paradai’ is excellent for warm regions like Southern California, Florida, and Texas, it’s hard to find! Most seed retailers have stopped selling it. Peruse local seed banks for seeds, or ask neighbors and friends who garden if they have a source.
‘Great Lakes 118’
Crisphead lettuces form tight-wrapped bunches of crunchy, tender leaves that resemble cabbage heads. They’re perfect for slicing into salads, burgers, or wraps; their crunchiness and mild flavors blend well in many fresh recipes. Sometimes labeled iceberg lettuce, crisphead types are common in grocery stores. Grow one yourself to see how homegrown produce tastes better than storebought!
‘Great Lakes 118’ is an improvement of the famous ‘Great Lakes’ cultivar. This new version is bolt-resistant and tolerant of heat. It’s an iceberg type with many layers of thin, crunchy, and green foliage. You’ll harvest the mature heads two to three months after planting.
‘Ice Queen’
‘Ice Queen,’ or ‘Reine des Glaces,’ sprouts frilly, fringed foliage in tight clusters. It eventually forms tight clusters of crispy greens that are mild, tender, and nutritious. Though it forms heads like iceberg cultivars, it also has dense layers of loose leaves that resemble summer crips types.
You may harvest ‘Ice Queen’ in a few different ways. Baby greens are ready for picking two or three weeks after planting, while loose leaves are pickable throughout the growing season. Mature heads form after two months—cut them off at their base for a complete harvest, or chop them two inches above the base to encourage new growth.
‘Nevada’
Another summer crisp type, ‘Nevada’ forms lush rosettes full of buttery, tender leaves. The flavors and textures are incredible, adding dimension to salads, wraps, and burgers. You may also blend the lettuce in smoothies, though you won’t enjoy the delectable tenderness you get with fresh eating.
‘Nevada’ stores well in cold storage. The best way to harvest it for storage is to cut off the heads on a cool morning and dunk them in ice water. Then, store the heads in the crisper drawer of your fridge; they should hold up well for a week or two before wilting.
‘Little Gem’
Romaine lettuce is similar to iceberg types, except it forms long spears of foliage rather than round heads. The spears have leaves with thick, crunchy stems and frilly, green margins. Like crisphead varieties, romaine types are commonly available in grocery stores and farmers’ markets.
Not all romaine grows the same. ‘Little Gem’ sprouts tiny rosettes that look more like summer crisp varieties than romaine ones! They’re perfect for fresh eating or any recipe calling for romaine hearts. The soft, green leaf tips are flavorful and tender, making ‘Little Gem’ a favorite of gardeners and chefs.
‘Truchas’
Romaine comes in red! Though most varieties have green foliage, ‘Truchas’ sprouts dense clusters of maroon-colored leaves that shine in overcast weather. It’s considered a mini-romaine variety because of the heads’ miniature sizes. Though they’re heat resistant, they also stand up well against harsh frosts and rainstorms.
‘Truchas’ resists infections from downy mildew and lettuce mosaic virus. It’s a good choice for gardens with recurring lettuce diseases. The plants grow well in the presence of pathogens, sprouting delicious leaves despite external pressures.
‘Parris Island Cos’
This type has been a classic favorite of U.S. gardeners since the 1950s! Researchers and breeders at Clemson University and the USDA created ‘Parris Island Cos’ so that hearty romaine lettuce would be available for farmers and home gardeners.
An upright, vigorous grower, ‘Parris Island Cos’ performs well despite the summer heat, growing long, pale greens with crunchy stems. It’s also a delicious baby green, offering young leaves for harvest 21 days after planting.
‘Rouge d’Hiver’
Red romaine cultivars look stunning in vegetable and ornamental gardens! ‘Rouge d’Hiver’ is one such variety that sports maroon leafy foliage. It stands upright, forming spears full of crunchy leaves. Grow ‘Parris Island Cos’ and ‘Rouge d’Hiver’ to enjoy green and red romaine throughout the warm and cool months.
Because of its frost tolerance, this variety grows well as a winter crop in mild zones without harsh frosts. Plant seeds in late autumn so the heads mature through December, January, and February. You may also grow this type in the summer, though it may taste bitter compared to crops growing under cool weather.
‘Jericho’
‘Jericho’ hails from Israel. It excels during warm, sunny days in late spring and summer, sprouting romaine leaves with crunchy stems and tender outer margins. Like ‘Paradai,’ this cultivar stood up well in tests completed by the Fair Oaks Horticulture Center in Sacramento. The plants grew for 73 days before bolting!
Though ‘Jericho’ forms small heads, it performs better as a cut-and-come-again variety. Snip the outer leaves for baby greens, or let the plants mature into small bunches. Baby greens appear after a month, while mature clusters form a few weeks thereafter.
‘Marvel of Four Seasons’
From romaine, we move on to butterhead lettuce! Butterheads form loose rosettes full of soft, tender foliage that is less crunchy than other types. They’re often the most sought-after varieties for farmers’ markets, fancy restaurants, and home cooks.
Red butterheads are more showy than green types. ‘Marvel of Four Seasons’ stuns growers with its easy-growing foliage and peak performance amidst hot weather. The wrinkled, scaly leaves condense into rough clusters that resemble rose flowers! Ornamental and delicious, this is the perfect variety for pretty gardens with edible plants.
‘Red Cross’
Another red butterhead, the ‘Red Cross’ excels in hot zones with summer drought. It sprouts lush, wrinkly leaves tinged with red where the sun hits them. Harvest the individual leaves, or let the plants form tight bunches after 48 days.
No matter how you grow the ‘Red Cross,’ you’ll love its hardiness. This type excelled in the experiment in Sacramento—the plants bolted after 77 days! Their tips had some singing, though they held up well against recurring heat and drought.
Though this type is drought tolerant, it’s more likely to bolt in hot climates. Keep the soil cool and moist to thwart the flowering period. Mulches like compost or leaf mold can help—add them to the soil in a two to three-inch thick layer to keep the roots cool.
‘Salad Bowl Blend’
If you can’t decide on a single type, try a blend with many varieties! The ‘Salad Bowl Blend’ is a great first choice. It has red and green loose-leaf types that work well for baby greens or individual picking later in the season. A longtime favorite in the U.S., this mix has been wowing gardeners for over 60 years!
Though ‘Salad Bowl Blend’ grows well in summer, it’ll perform better when it starts under cool weather. Sow seeds continuously, starting two to four weeks before your average last frost date. You’ll have lettuce to pick all summer long!
