Lettuce Bolting: Can It Be Stopped?

Lettuce is the crop of choice for both experienced and beginner garden enthusiasts. A quick-growing plant that can be eaten during almost any of its life stages, and available in hundreds of varieties, this vegetable is everywhere! But just like any other plant, lettuce goes through a life cycle. It starts as a seed, developing leaves, putting out a flower stalk to get pollinated, and then producing seed and dying. This natural process can mystify some, until now. While bolting lettuce is inevitable, controlling bolting lettuce is something that you can do to extend your harvest. 

Lettuce loves growing in the garden during the cool season, be it spring in the US’s Midwest, or winter in coastal California. This vegetable will quickly start bolting in heat or any temperatures above 80 degrees. By mimicking a cool season with just a few tricks when it’s actually the mild heat of summer, it’s possible for lettuce plants to prolong their production phase and delay bolting. 

Tricking lettuce into believing it’s still in a cool season may seem difficult at first. However, by keeping direct sun off the leaves or planting under the cover of trees or shade of a building, these leafy vegetables can be tricked into believing that it’s not quite time to bolt. 

Later in the summer, depending on your region, these greens may just be impossible to grow. As one of the early vegetable crops that prefers temperatures below 75 degrees, you may want to wait until temperatures are ideal again. When it’s 80 degrees or more during the heat of the day, these vegetables just won’t thrive anymore. It would be best to wait until the fall before adding lettuce to your garden again.  

What Causes Bolting Lettuce?

Lettuce bolting
When the weather warms up, lettuce bolting is nearly inevitable. Source: woodleywonderworks

Lettuce bolts because it is trying to move onto the next step in its life cycle. These leafy vegetables don’t bolt because a gardener is ‘doing it wrong’ or is killing their plants. Bolting is the natural progression of the life cycle in the lettuce’s attempt to reproduce. 

When lettuce bolts, it’s attempting to flower, which once pollinated will turn to seed. Lettuce isn’t so much on an ironclad timetable but instead responds to its surroundings to know when it’s time to reproduce. When days get longer, hotter and dryer (i.e. when summer starts), lettuce will start to flower. As pollinators are more active in the spring time when flowers are blooming, lettuces have grown and adapted their life cycles to when they’re most likely to be pollinated. 

Signs of Bolting

Gardeners can watch for early signs of bolting by keeping an eye on the center of the lettuce head. The center will thicken and begin to elongate forming a new center. This is where the flower stalk is forming. It’s possible to snip back this centerpiece to delay the bolting process, but the leaves may still taste a bit bitter afterward. 

How To Slow Or Stop Bolting

Bolted lettuce buds
Tips of bolted lettuce forming flower buds. Source: wayneandwax

As lettuce responds to physical responses, you can extend the life of lettuce, and delay (not stop) the bolting process by trying to replicate the factors it wants to live in. On hotter days, shade it from blaring sun and heat. For dryer days, make sure that the ground around it is moist, and on longer days, provide shade so that the lettuces internal clock doesn’t start the bolting process. 

Extending the Grow Season

Gardeners can mimic the ideal garden that these leafy greens want to live in, even during weather where it would otherwise bolt. By tricking the plants into thinking it’s living in a different season, you can prolong your harvest. The most important factor in growing lettuce at times of the year when temperatures get near 75 degrees during the day, is to provide shade. 

Shade cloth comes in handy under these circumstances and conveniently comes in several different types. For growing lettuce during a warm season, a woven white or red cloth is ideal. The woven fabric provides more airflow, keeping the plants cool and discouraging diseases. Make sure to avoid buying a shade cloth designed to shade humans or plants such as orchids, as they will block out too many of the sun’s rays. A shade cloth that advertises itself as shading out 30-60% of the sun’s rays is ideal. Make sure to install it high enough above the plants that it doesn’t weigh down the leaves. This type of cloth is ideal for use in the summer as it lowers the temperature the lettuce grows in while retaining moisture. 

Bolt Resistant Varieties

You are not the only gardener battling heat and trying to get your leafy vegetables to grow even when the weather isn’t ideal. Many new varieties have been developed over the years to be bolt resistant crops. This means that while the plant will eventually put out a flower stalk and complete its life cycle, that process is delayed to help you extend your lettuce harvest. Some of those varieties are: 

  • Sparx (romaine)
  • Salvius (romaine)
  • Starfighter (green leaf)
  • New Red Fire (red leaf) 

These seeds may be a little hard to find at first (try online providers like Jonny’s), but are well worth the search as they will extend your growing season for what many gardeners call their favorite crop. 

Bolting Possibilities

Once a lettuce plant bolts, the world doesn’t end! There are several possibilities for what to do with your bolting lettuce plant. Lettuce can provide a range of beautiful flowers once it has bolted, and these flowers can attract pollinators to your garden to pollinate other plants you have growing nearby. If you need the garden space, pulled plants can be safely fed to pets such as a guinea pig or rabbit. You can even wait until aphids appear on the tender leaves of the plant to pull it – using it as a trap crop to help protect nearby plants. 

Lastly, and one of the most important uses for bolting lettuce plants is using it to collect seed for the following year! Many home gardeners (and farmers as well!) love to save their own seeds to keep for the following year or trade with other growers. This is an age-old practice and a wonderful way to help grow crops that are adapted to where you are growing. Keep in mind that if you’re growing a hybrid, the plants you get the following year will most likely be a bit different. In order to save seeds correctly, let the lettuce plants continue to grow and put energy into the seeds throughout summer. Place a small mesh bag around the seed head to collect it and keep it from being carried away in the wind. 

Frequently Asked Questions

A row of lettuce in flower
Once flowering, leaves will be more bitter although technically still edible. Source: photofarmer

Q: Is it safe to eat bolted lettuce?

A: It is safe to eat bolted lettuce although the flavor will be more bitter than is usual. 

Q: Will bolted lettuce regrow?

A: Bolted lettuce, when cut down to its base will regrow under the right conditions. If summer is too hot, the entire plant may die, but in cooler temperatures, it may resprout and continue to produce. 

Q: What to do with lettuce when it bolts?

A: Growers have several options when lettuce plants bolt, flowers can be used to attract pollinators, it can be used as a trap crop, given to pets that can eat leafy greens (chickens or bunnies), or even saved for seed.