Lettuce is a cool-season vegetable, and in most home gardens, it is planted in the early spring, harvested in late spring to early summer, and then discarded in favor of other vegetables for the middle of the summer.
Some gardeners might replant a second crop of lettuce as the days grow cooler in fall, but most do not grow lettuce at all in the midsummer period, focusing instead on warm-season vegetables. Savvy gardeners plant lettuce among other warm-season vegetables, such as tomatoes, so that by the time the lettuce is finished in early summer, the warm-season vegetables are beginning to take over the garden space.
Lettuce grows best in a temperature range of about 45 to 75 degrees. In weather hotter than that, the leaves become bitter to the taste. When leaf lettuce bolts—which means they begin to send up its flower shoots—its a signal that the production of edible lettuce is done for the season. Leaves harvested after this point will be quite bitter to eat.
But here are some ways in which you can keep lettuce plants producing throughout the summer.
Lettuce is a cool-weather crop that can be tricky to grow in the hot summer months. However, with some planning and preparation, you can have a bountiful harvest of lettuce all summer long. Here are the key techniques for growing lettuce in summer:
Choose Heat-Tolerant Varieties
Not all lettuce varieties are created equal when it comes to heat tolerance, Look for looseleaf and oakleaf lettuce cultivars that are specifically bred to withstand summer temperatures without bolting or becoming bitter, Some great options include
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Black Seeded Simpson – A fast-growing, looseleaf lettuce with excellent heat tolerance One of the most reliable summer lettuces.
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Salad Bowl – A frumpled green oakleaf type that stays sweet even in hot weather.
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Red Sails – A stunning red oakleaf variety that holds up to summer heat.
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Green Star – A ruffled green leaf lettuce that resists bolting and bitterness.
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Buttercrunch – A super heat-tolerant bibb-type lettuce that forms loose heads.
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Jericho – A romaine lettuce bred for hot climates like Israel. Extremely slow to bolt.
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Craquerelle du Midi – A French heirloom romaine with good summer performance.
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Little Gem – A compact romaine-type that thrives in heat.
Consult seed catalogs or local nurseries to find heat-resistant varieties best suited to your climate. Stay away from more sensitive types like iceberg, butterhead, and crisphead lettuce.
Plant at the Right Time
Timing is everything when it comes to growing summer lettuce. In most climates, the ideal planting window is in late spring after the last frost but before the onset of hot weather. This gives the lettuce a chance to mature and be harvested before the peak of summer.
For a continuous crop, sow small batches of seeds every 2-3 weeks until temperatures rise above 80°F. You can also start transplants indoors and set them out in early summer. Focus on seeding in the coolest part of the day and keep newly seeded beds well-watered.
In very hot climates, grow lettuce as a fall/winter crop and avoid summer plantings altogether.
Provide Partial Shade
Lettuce prefers cool, moist conditions. Help keep your summer lettuce crop in the optimal temperature range by providing some shade, especially during the hottest part of the day.
Use taller vegetable plants like tomatoes, pole beans or corn to shade lettuce beds. Or plant lettuce on the east side of trellises so vines will shade the beds later in summer. Dappled shade under trees or shade cloth also helps. Just be sure lettuce gets sun early or late in the day for best growth.
Maximize Soil Moisture
Consistent moisture helps lettuce tolerate heat stress. Use drip irrigation or hand water to keep soil moist but not soggy. Mulch heavily around plants to conserve moisture and keep roots cool.
In very hot, dry conditions, an afternoon shower from the hose can revive wilted lettuce plants. Just don’t blast them directly.
Harvest Frequently
Regularly harvesting outer leaves prompts the plant to generate new growth. Leaving mature leaves to sit promotes bolting in hot weather.
Make your way through the lettuce patch at least once a week, harvesting the largest leaves and leaving the small, immature ones at the center. This will extend the productive life of the plant.
Grow in Containers
Lettuce is well-suited to container gardening. Focus on compact varieties and keep pots in a partly shaded spot, moving them as needed to avoid excessive sun exposure. Make sure containers have drainage holes and use a high quality potting mix. Keep soil consistently moist.
Containers heat up quickly so pay close attention to watering and shade needs. But they offer more control over growing conditions compared to in-ground beds.
Time Summer Plantings
In hot climates, grow lettuce as a fall/winter crop and take a summer break. Start seeds indoors in mid to late summer and set transplants out approximately 6-8 weeks before your first fall frost date. This avoids the pitfalls of growing in summer.
Focus on faster maturing leaf varieties over head-forming types which take longer to mature. Beans, peas, chard and kale are better summer vegetable options.
Adapt Your Expectations
The bottom line is that lettuce will never thrive in peak summer. But by selecting the right varieties and managing conditions, you can continue harvesting a modest crop. Just temper your expectations in the hottest months.
Prioritize pest and disease prevention as plants under stress are more vulnerable. Be diligent about heat mitigation techniques. And stay on top of watering as lettuce relies heavily on moisture. A little extra care goes a long way!
Troubleshooting Summer Lettuce Issues
Even if you follow best practices, lettuce can still struggle in hot weather. Here’s how to address common problems:
Bolting – Rapid growth of the central stalk and onset of flowering. Reduce stress and harvest leaves early and often.
Bitterness – Heat and age cause leaves to become very bitter. Frequent harvesting helps avoid this.
Tipburn – Browning along the edges of leaves due to lack of calcium. Ensure consistent moisture.
Insect pests – Aphids, cabbage worms and slugs target stressed plants. Monitor closely and use organic remedies.
Downy Mildew – Yellow lesions on leaves followed by white mold. Improve airflow and avoid wetting foliage.
Bottom Rot – Wet soil and high temperatures cause rotten stem ends. Improve drainage and reduce irrigation.
Be prepared to pull plants that are under severe disease and pest pressure to avoid spreading issues. Replant in fall when conditions improve.
The Key is Flexibility!
Growing lettuce in summer can be an exercise in adaptability. Stay observant so you can modify your approach as needed to address challenges. Maintaining a garden diary is extremely helpful for this.
Be willing to tweak your lettuce planting schedule, provide extra shade as temperatures climb, or switch to containers if your in-ground beds aren’t working.
Keep notes on which varieties perform best so you can fine-tune your selections each year. Gardening is always a work in progress!
With the right cultivars and care, you can harvest lettuce all season. Patience and persistence pay off when it comes to pushing the limits of heat tolerance. Don’t be afraid to experiment so you can enjoy fresh, homegrown lettuce – even in the dog days of summer.
Harvest Leaf Lettuce Frequently
If you keep lettuce leaves cropped short, the plants will continue to produce new leaves well into the summer. Allowing leaves to become large and mature signals the plant to send up flower stalks and produce seed, which is the point where it will no longer be edible. Keep your leaf lettuce cropped short, even if it means discarding some leaves because there is more than you can eat.
Choose the Right Type of Lettuce
Choose leaf lettuce varieties rather than head-forming lettuces. You can start harvesting leaf lettuces as soon as the outer leaves reach about four to six inches in height. If you cut just the outer leaves, it enables the remaining center leaves to continue growing, and youll have baby leaves to enjoy. This is called “cut and come again” harvesting, and some lettuce varieties are marketed as being especially suitable for this kind of harvesting. Not only do you start harvesting early, but cutting like this tends to shock the lettuce plant, preventing it from thinking it has matured and is ready to bolt and go to seed. Here are a few cut and come again types of lettuces that have a uniform, upright growth for the best baby leaves:
- Romaine
- Summer crisp
- Oakleaf types with flatter, lobed leaves
- Grand Rapids types with broad, crinkled, frilly, loose leaves
- Green leaf and red leaf
Head-lettuces, on the other hand, take a while to develop mature heads, and they sometimes bolt even before decent edible heads can form. Leaf lettuces are a much better choice for continued production. Some common head-lettuce varieties include:
HOW TO SUCCESSFULLY GROW LETTUCE IN THE SUMMER HEAT
FAQ
Can lettuce grow in hot summer?
Lettuce is a cool-season vegetable, but some varieties have been bred to better tolerate hot weather. Here are some of the most heat-resistant varieties that I’ve found: Romaine – Jericho, Parris Island. Batavian – Nevada, Sierra, Tahoe.
Does lettuce like full sun or shade?
Lettuce thrives and grows fastest in full sun, but it also grows well in light shade. In warmest regions, try to select a growing spot that offers afternoon shade. The ideal soil for growing lettuce is moist but well-drained.
Is July too late to plant lettuce?
Lettuce can be sown direct outdoors from early spring until late summer, for crops through summer and fall.Mar 26, 2022
Do you grow lettuce in the summer?
You grow lettuce in the summer! It seems unfair — just when we really need lettuce as the foundation of a summer salad, the lettuce wants to pack up and spend its summer at Lake Tahoe (or some other cool spot). Here’s how you can have your lettuce and heat it too. Lettuce prefers the cool days of spring and fall with air temperatures in the 60s.
How can I keep lettuce going all summer long?
You can keep lettuce going all summer long with a few simple tricks up your sleeve. Here’s what I do in order to harvest lettuce well into September: 1. Grow loose-leaf varieties. In general, loose-leaf lettuces are more heat-resistant and slower to bolt than lettuce varieties that form heads.
How do you grow lettuce in warm weather?
To successfully grow lettuce in warm weather, consider the following strategies: Germinate seeds indoors, managing light, soil moisture, and soil temperatures well. Use shade cloth or grow taller plants as companion plantings to cast shade on your lettuce plants, especially in the midday sun.
Can lettuce go through summer without bolting?
As any gardener knows, it can be a struggle to keep lettuce going through summer without bolting, but there’s hope! You can grow a variety of heat-tolerant lettuces well into September and enjoy fresh, crisp salad greens even when everything else starts to wilt. These are my favorites! 1. Grow loose-leaf varieties. 2. Sow seeds at the right time.
When should I plant lettuce?
In spring when all the plants are still small, your lettuce will have ample sunshine to develop more quickly. As summer gets going and the days get warmer, those other plants will grow taller to provide shade and relief to the lettuces. When deciding where to plant, it’s better to give lettuce morning sun or partial sun (where it’s shaded midday).
What temperature do lettuce seeds germinate?
Lettuce is a cool-season vegetable, and seeds will germinate at 35°F/1.6°C, but the optimum soil temperature is 70 to 75°F/21 – 24°C. The maximum temperature at which lettuce seeds will germinate is 85°F/29.4°C. Extended periods of temperatures above 85°F/29.4°C will cause lettuce to bolt, a common challenge to growing lettuce in summer.