What Does Bolting Mean?
Bolting is a plant's way of informing you that its time in your garden is almost over. Plants typically bolt due to stress—the weather is changing, the plant has run out of space to reach its full maturity, or it’s used up the nutrients in the soil. Instead of putting more effort into its own survival, the plant will instead begin looking toward the survival of its own kind. It does this through producing seeds.
Plants, you see, have a strong desire to continue their line for generations to come, and the formation of seeds is how it ensures that dozens, if not hundreds, of copies of itself will exist after it dies.
Why Does Lettuce Bolt?
Lettuce typically bolts due to heat stress or lack of water. Lettuce plants love the cooler weather typical of spring and fall in many places (or winter in warm climates), and they'll become stressed as soon as the weather warms (any temperatures above 80 degrees F). Lettuce plants are even sensitive to day lengths, so more hours of sunlight in the summer can sometimes be enough to tell lettuce it's time to produce seeds.
If you think about what the plant wants to do, it’s easy to see how any negative environmental triggers would push the plant into taking action to ensure its survival for the next growing season. Not only are lettuce plants motivated to reproduce, they're also clever. Their wiring tells them to bolt when the days lengthen and grow warm, just when pollinators are most active and likely to pollinate their flowers for them.
What Does Bolting Lettuce Look Like?
When a lettuce plant bolts, it sends up a tall central stalk and begins to form yellow flowers (each of which will produce seeds).
Why Is My Lettuce Bitter?
Once you notice these signs of bolting in your lettuce plants, you might also notice a bitter flavor. This taste remains in the leaves even if you cut off the seed stalk.
You might also notice a white sap coming from the base of your lettuce plant, particularly bolting romaine lettuce. Lettuce plants reaching the end of their lifecycle release this sticky, milk-like substance called lactucarium, which comes from the Latin word for milk: lactus. (The botanical name for lettuce, lactuca, actually stems from the same root, so this milky sap literally gave lettuce its name.)
It's this sap that's giving your leaves the bitter flavor.
So, Is It Safe to Eat Bolting Lettuce?
The leaves of bolting lettuce plants are still 100 percent safe to eat. Their flavor, however, will change. These plants are long past their peak of flavor now that their only focus is producing seeds.
The bigger consideration is not are they okay to eat, but do you want to eat them? You might find the leaves too bitter or rubbery. Do a little taste test and see if the flavor is still acceptable to you.
This might surprise you, but the milky sap is also completely edible, though bitter. It's made of latex that's naturally found in the lettuce plant.
How to Prevent Your Lettuce Plants from Bolting
You can take steps to delay your lettuce from feeling stress and extend its time in the garden before it focuses on seed production.
Plan Ahead
First, only plant your lettuce when you have at least 45 days ahead when the temperatures are expected to stay below 75°F.
Provide Shade
Should the temperatures exceed 80°F, try to give your leafy greens some afternoon shade, perhaps by growing taller plants next to them or moving their container to a covered patio. Shade cloths draped over your lettuce plants can protect them from the full force of the sun and trick them into thinking it's still their ideal climate for a while longer. (If you're shopping around for a shade cloth, look for something that block 30 to 60 percent of the sun's rays for your lettuce plants.) These cloths will also lower the temperature underneath by as much as 10 to 20 degrees and help to retain moisture.
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Water More Often
Instead of giving lettuce plants a deep watering once a week as you might other plants, consider watering your greens a little every single day or every other day to keep the soil moist but not soaking. Water is like a cooling balm to your lettuce on a warmer day.
Harvest Leaves
Lettuce plants will eventually bolt with the changing of the seasons, but you can prolong your plant's remaining time in your garden by harvesting the outer leaves frequently.
Grow the Right Plants
Once your temperatures are consistently above 80 degrees, stop trying to grow lettuce and instead plant greens like New Zealand spinach, malabar spinach, and arugula, all of which can stand the heat, until it's time for your cool season again.
What to Do When Lettuce Bolts
First of all, don't stress. Your lettuce isn't going to seed because you're a horrible gardener. Your garden is not the place that salad greens go to die. Seed formation is a natural progression in the life cycle of a lettuce plant. Remember that our plants have a purpose far beyond what we are growing them for.
As the gardener, though, it’s up to you to determine what happens once your plants are going to seed. You can:
- Pull your lettuce from the garden and replace it with something that will grow more optimally in your current garden conditions. Cut the lettuce right at the base, rather than yanking it out by the roots, to avoid disturbing your other plants. If you compost the plant, it will continue to provide nutrients for your garden as organic matter.
- Harvest a couple of leaves and do a taste test to see if they’re too bitter or rubbery to eat. I keep eating my leaves as long as I can.
There's a third possibility, and I think it's the most fun for us as the gardener. You can leave your bolting plant in the garden to enjoy for a while, assuming you don't immediately need that garden space. In its process of forming seeds, your lettuce plant will also create a lot of beautiful flowers that will attract pollinators to your garden.
Once the seeds form, you can collect them, and then you have free seeds for your next cool season! Assuming the lettuce plant wasn't a hybrid, the seeds will remain true to the original plant. Here are the easy steps to save your own lettuce seeds.
Try to Save Your Own Seeds from Bolting Plants
To me, this is like making lemonade when life gives you proverbial lemons. You can't have delicious leaves from the plant anymore, so you might as well get some seeds out of it, right?
Think about how plants can reproduce themselves, either by growing new roots on a cutting or by growing all the way to the end of their life cycle and producing their own seeds to create more and more of themselves in the seasons to come. I mean, how many other things in the world can do that?
Even cooler, the seeds you save over time will become better and better adapted to your particular growing conditions, which means more garden wins for you!
Thanks for bringing back the kitchen garden with me one bolting lettuce plant at a time!
