Bolting

Like an arrow from a bow, many plants may suddenly send up new growth, covered with flowers. This is called bolting.

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There are many causes of bolting and it is not necessarily a bad thing. Here, we will explore the causes of bolting and the plants most likely to demonstrate this behavior.


Plants are hardwired to ensure the survival of their genetic information. Plants have evolved to generate flowers and create seeds at a time of year that increases the chances of success for future generations. Sometimes conditions can cause a plant to go to seed earlier than usual (or earlier than we would like). This brings us to bolting.

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When a plant bolts, it goes to seed suddenly and prematurely. Flowering stems seem to shoot up overnight. These stems pull nutrients away from many other plant processes and edible parts often taste bitter.

Photos of bolting lettuce plants by Kate Russell

What causes bolting?


Bolting is caused internally by plant hormones. These hormones can be triggered by a sudden heat wave or cold snap, changes in sun exposure, water stress, or insufficient nutrients in the soil. Cool season annuals, in particular, have evolved to go to seed when cool temperatures turn warm or hot. Mulching, regular watering, and planting resistant varieties can all help reduce the chance of bolting.


Which plants tend to bolt?

Lettuces are very prone to bolting. Onion, celery, basil, spinach, beets, rhubarb, and members of the brassica family (broccoli, cabbage) are also likely to bolt. Unfortunately, bolting often makes plants taste bitter. In most cases, once bolting starts, there isn’t much that can be done. Harvest what is edible. Rhubarb is generally the only exception. If rhubarb starts to bolt, the flowering stems can be removed without negatively impacting the crop. You can reduce the likelihood of bolting by including these plants in your shade gardens. Before removing other bolting plants, however, consider taking advantage of this garden opportunity.


Take advantage of bolting

Rather than cutting down plants that have bolted, consider leaving them alone and letting them do their thing. By leaving lettuces in my garden after bolting, I now have lettuce popping up all over the place. If a more tidy garden is desired, seeds can be collected from plants that have bolted and planted more deliberately. Personally, I have a high tolerance for a little chaos in the garden. By allowing bolted plants to go through their life cycle, fertilized seeds end up in a larger variety of locations. Plus, the flowers provide pollen and nectar to beneficial insects. As a result, I have a far bigger crop and more biodiversity!

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