The Nuts & Bolts of Bolting

  • Difficulty Rating: Beginner
The Nuts & Bolts of Bolting

What’s it Mean When a Plant “Bolts” or “Goes to Seed”?

Bolting is one of those terms long-time farmers know and bemoan, but say, “Hey, your lettuce is about to ‘bolt’” to a newbie gardener, and a quizzical look is probably going to be their response.Bolting sounds like the plant is about ready to pull up roots and start running for the hills, and in a way it is.

Bolting is a term used when a plant rapidly transitions from a vigorous green-growth phase to suddenly sending up unwanted flower heads. So, when a squash or tomato plant begins to put on flowers, which will become edible fruits, that is not bolting. But, when an edible leafy green like spinach sends up a flower head, that growth is called bolting. It happens rapidly, within just a few days. And, it means that the leafy green crop is about kaput for the season.

In the case of the tomato, we want it to put some focused energy into producing flowers that become tasty fruits, and it will do this for most of the growing season once it begins to flower. But with leafy greens like basil or cabbage or kale, we want the plant to stay focused on generating big crops of robust leaves rather than squandering its limited resources on creating flowers for seed.

Bolting can happen for a number of reasons, most of which come down to stressful impacts. These traumatic moments trigger the plant to refocus its growth patterns, investing in creating seed, which will create its next generation. In the process, it begins allowing itself to peter out. Stems become tough and sturdy to support seed heads, and leaves become less plentiful and sweet.

Many spring crops are sensitive to high heat days of summer, which may cause them to begin forming seed.  In other situations, plants like chard may try to set seed when stressed by droughty conditions or pest infestations.  Overcrowding plants is another cause for bolting; too little room may mean too few resources for congested veggies. And, in some cases, seasonal light changes can also trigger a plant to bolt.

broccoli harvest; some stalks beginning to bolt

To avoid bolting in the heat, try planting heat-tolerant varieties. Seeding them into partially shady locations may also keep your salad bowl full for summer. Be sure to thin your crops, monitor for pests, and keep your watering consistent to encourage your leafy edibles to keep calm and plod along cooperatively. If your bolting crop is an edible flower like broccoli or artichoke, harvest it before the flower even hints at opening.

Even if you employ all of these techniques, some plants will just up and bolt on you anyway. Putting on flowers to create seed and spread their genetics and progeny is part of nature. If you happen to see your crops sending up a tiny bud, try pinching it out early using a pair of Fiskars® Softouch® Micro-Tip® Pruning Snips for a clean, precise cut. Sometimes, this will help the plant revert to its green growth plan instead. Or, just uproot the uncooperative edible, and serve it for your next meal. The seeds from many crops won’t hold true to form for planting in the future without some very careful pollination management.

Cilantro flowering will form Coriander

That being said, one crop that’s notorious for bolting is Cilantro. When flowering, Cilantro makes a great pollinator attractor. Plus, the seeds that eventually form are the spice Coriander, which is fantastic in any number of cuisines – used green or dried for winter meals.