What to Do About Bolting Lettuce: 8 Simple Steps

Prevent Bolting for Fresh, Tasty Lettuce Leaves

By
Marie Iannotti
Garden Writer Marie Iannotti
Marie Iannotti
Marie Iannotti is a life-long gardener and a veteran Master Gardener with nearly three decades of experience. She's also an author of three gardening books, a plant photographer, public speaker, and a former Cornell Cooperative Extension Horticulture Educator. Marie's garden writing has been featured in newspapers and magazines nationwide and she has been interviewed for Martha Stewart Radio, National Public Radio, and numerous articles.
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Updated on 06/04/24
Reviewed by
Barbara Gillette
Barbara Gillette
Reviewed by Barbara Gillette
Barbara Gillette is a Master Gardener, herbalist, beekeeper, and journalist. She has 30 years of experience propagating and growing fruits, vegetables, herbs, and ornamentals.
Learn more about The Spruce's Review Board
Lettuce leaves bolting between dark red vegetation

The Spruce / Randi Rhoades

Project Overview
  • Working Time: 15 - 20 mins
  • Total Time: 15 - 20 mins
  • Skill Level: Beginner
  • Estimated Cost: $3 to $5

Vegetable gardeners often talk about their plants "bolting," which simply means that the plant sends up a flower stalk and goes to seed. When plants flower, it's generally considered a good thing; however, a quick growth in vegetables grown for their leaves, such as lettuce, spinach, cabbage, and other cole crops, bolting causes the flavor to turn bitter and the leaves to get smaller and tougher, making them inedible. Bolting is completely normal and common in cool-season greens, like arugula, lettuce, and spinach. Other common garden plants that bolt include beets, broccoli, and herbs such as cilantro, basil, and dill. Today, we'll be discussing what to do about bolting lettuce, why it bolts, and how to prevent it in the first place.

Why Lettuce Bolts

Bolting tends to happen when the temperature heats up. Heat may be a factor in bolting if high temperatures occur when the plants are nearing maturity. If lettuce seedlings are exposed to 40 to 50 degrees Fahrenheit temperatures for several days in a row, they will start forming flower buds, although the flower stalk won't shoot up until the weather warms. Monitor your lettuce for bolting when daytime temperatures reach above 75 degrees Fahrenheit and nighttime temperatures are over 60 degrees Fahrenheit.

Dry conditions may also contribute to bolting. Plants that feel threatened by harsh temperatures will often go to seed. Even exposure to cold while the plants are seedlings can play a role. Bolting can be delayed to extend the harvesting season if you pinch the buds as they begin to flower.

Fun Fact

The name "iceberg lettuce" dates back to early 20th century California—refrigerators were not available so to prevent spoilage in transit, farmers would cover the lettuce in crushed ice.

What You'll Need

Equipment / Tools

  • Wide wood board
  • Soil thermometer
  • Shade cloth or row covers

Materials

  • Slow-bolt lettuce seeds

Instructions

How to Prevent Lettuce From Bolting

  1. Purchase the Right Seeds

    Some cultivars are quicker to bolt than others. If you have trouble growing lettuce in the summer, it can't hurt to give slow-to-bolt cultivars a try.

    Many of these seeds will have names that hint at their bolt resistance, like "Slobolt" and "Summer Bibb." Among the older seed varieties, crisphead lettuces in the romaine or cos group tend to be the slowest to bolt, while looseleaf lettuce tends to be the quickest.

    sowing lettuce seeds

    The Spruce / Randi Rhoades

  2. Choose a Shady Spot

    Plant lettuce in a shaded spot in the garden, such as tucked under taller plants, or grow it in pots that can be moved to a shadier site. Regular watering helps to keep the soil cool and the leaves succulent throughout summer.

    Choosing a shady spot to grow lettuce

    The Spruce / Randi Rhoades

  3. Keep Soil Temperatures Cool

    When starting seeds in the summer, thoroughly soak the area with cold water a few days before sowing. After watering, cover the damp soil with a wide board. Repeat this process daily if the weather is particularly hot and dry.

    Within a couple of days, the soil under the board will be cooler than the surrounding soil. Test with a soil thermometer to be sure you've achieved the correct temperature for your seeds to sprout.

    Sow your seeds, water them, and cover the soil again with the board. Check daily for signs of germination. At the first sight of green sprouts, remove the board.

    Soaking seedlings

    The Spruce / Randi Rhoades

  4. Try Using Shade Cloth

    Shade cloth also can be used to protect young seedlings and tender leafy greens as it is specifically designed to let in rain and sun but, at the same time, protect the vegetables from strong UV rays that can cause early bolting. You will need to provide supports along with the cover to keep the cloth elevated above the plants and give them room to grow.

    Lettuce head with other herbs and greens growing in garden box under shade

    The Spruce / Randi Rhoades

  5. Water Regularly

    Because of its shallow roots, lettuce requires constant watering. Keep the soil moist at least one inch deep, and check levels and soil moisture at least twice a week. During the summer or when it gets hot, you may need to water lettuce more frequently.

  6. Add Mulch

    You can add about three inches of mulch around the plants to seal in more moisture and keep watering regulated, especially after heavy rain. Mulching can also help control any weeds that may crop up around the lettuce.

  7. Plant at the Right Time

    The season in which you plant seeds can also help prevent bolting lettuce as they will need to be harvested sooner. Try planting lettuce in the early spring, harvesting the crops, and planting again in the fall.

    Tip

    Harvesting the outer leaves of the lettuce plant can extend the season. While it does not delay bolting, it can allow for longer harvests.

  8. Watch for Flower Buds

    If you see your cool-season vegetables start to form flower buds, pinch out the buds. Once the plant has begun the process of flowering and reseeding it will eventually bolt, but you may be able to extend your harvest a little longer by pinching out the flower buds early on.

    Small yellow and white flowers from lettuce bolting closeup

    The Spruce / Randi Rhoades

FAQ
  • Can I eat lettuce that has already bolted?

    Yes, you can still eat lettuce after it has bolted. It is best to eat bolted lettuce in dishes that require cooked lettuce or a bitter green as the lettuce will not be as tender and sweet if it were eaten fresh.

  • Does lettuce grow back after bolting?

    Lettuce plants will not grow back if they have bolted. Bolting lettuce is caused by a lettuce plant flowering and seeding, which signifies the end of the plant's life cycle. If your lettuce plant has bolted, wait until the proper growing season and plant a new crop.

  • How do you make bolted lettuce taste better?

    Soaking leaves in cold water for up to ten minutes can help return some of the sweetness to the lettuce. Be sure to use clean, distilled water when soaking. You can also try washing, patting dry, and refrigerating lettuce that has bolted.

How to Grow Lettuce
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  1. Lettuce. University of Maryland Extension