Understanding Plant Bolting and Strategies to Avoid it

Understanding Plant Bolting and Strategies to Avoid it

Bolting is what happens when a plant flowers and produces seeds before its expected time. It is not desired, and thankfully, numerous strategies exist to help reduce or avoid it. Here, we'll discuss why plants bolt early, which plants are most vulnerable, methods to prevent bolting, and how to make the best of it.

Bolting 101

A horticultural term, bolting, describes when a plant produces a flowering stalk before it has been harvested. This is the plant's attempt to make seed, shifting its energy from growing the desired crop to reproduction. This process is often referred to as "going to seed."

Generally, a small flower bud appears in the middle of the plant or stem and then rapidly grows in height. Some vegetables, such as broccoli, cauliflower, lettuce, bok choy, and other leafy greens, are particularly prone to bolting in hot weather.

Generally speaking, bolting happens only after months of providing a good harvest. However, sometimes the plants are induced to move on to this stage too early, thus bypassing the normal expected growth and production. 

Why Do Plants Prematurely Bolt?

The common factors that induce bolting include temperature changes, heat waves, the temperature of the soil, and cultivating crops out of season. Other reasons for bolting may include lack of sufficient sunlight, too much shade, infrequent watering, inadequate nourishment, or root-bound plants when they are still seedlings.

The Effects Of Bolting

When a plant bolts, its flower spike and seeds emerge while the other parts of the plant become less palatable. This is especially true for lettuce, spinach, and similar leafy greens, which become both more bitter in taste and tougher in texture. Accordingly, it is wise to harvest as much as possible as soon as signs of bolting become evident. Some people don't mind the slight bitterness, so it is up to you whether you continue harvesting from bolted plants.

Is It Detrimental To The Plant If It Bolts?

Crops are still edible after they bolt, even if they're not perfect. The bolting stems and flowers can be edible, too. They might be a bit hard sometimes, but they make a great addition to soups, stews, roasts, and more.

In addition, pollinators are attracted to the blossoms of bolting plants. We frequently leave them in our garden, even after they are no longer useful to us, to provide a food source for bees. Our bolted brassicas and herbs are especially popular.

Five Strategies to Avoid Plants Bolting Prematurely

  1. Pick plants that are suitable for the climate and time of year.

    Before sowing any plants, research the preferred temperatures and conditions of the vegetable. Trying to cultivate a cool-weather vegetable during the summer is unlikely to be successful.  

  2. Provide shade and adequate hydration during heat waves.

    No matter how much thought has gone into what to plant and when, a sudden heat wave can still affect the garden. Therefore, heat-sensitive plants should be given extra attention and care during such times. 
    • Set up temporary covers such as shade cloth.
    • Apply mulch to the soil to reduce any temperature fluctuation in the area around the roots.
    • Make sure to give your garden an extended and thorough watering the day or morning before a heat wave.

  3. Mulch at planting time to prevent future temperature issues.

    It may surprise you to learn that the temperature of the soil surrounding plant roots is more impactful on plant growth than the air temperature. To help keep soil temperatures consistent, a layer of mulch, such as compost, wood chips, straw, or shredded leaves, should be placed around the base of plants and should be around 1-2 inches thick. This mulching technique insulates the soil and helps keep moisture levels steady.

  4. Set up a regular watering schedule.

    A regular watering schedule is essential to maintain consistent ground temperatures and reduce plant stress, thus preventing them from bolting. Instead of watering a little bit each day, water generously, slowly, and deeply a few times a week. This will ensure deep root development, further protecting plants from extreme temperatures or drought.

  5. Make sure the plant is getting adequate sun.

    If a plant does not get the sunlight it needs, it will start to grow tall and spindly in an effort to reach the sun. This will lead to a decrease in the plant's ability to photosynthesize and use nutrients and will cause stress for the plant. As a result, it may start to generate seeds instead of an excellent edible crop. So, it is crucial to adhere to the sunlight requirements for any given plant.

Can You Prune Bolted Plants To Continue Growth?

You are probably wondering if it is possible to end the bolting process by snipping the flowering stem. Unfortunately, no. It is too late to change the course of the plant as it has already shifted to seed production internally. There's no way to reverse it now.

Still, it is possible to decelerate the bolting by snipping off the early flowering buds or stem. For instance, it is common to routinely pinch back the flowers on annual herbs such as basil to lengthen the harvesting period.

Pruning the flower stalks from plants that create multiple small leaves (like arugula or basil) is particularly successful in prolonging the plant's life. However, cutting the flowering stem off something like broccoli, cabbage, or cauliflower will not cause the plant to generate a large head. Instead, these may generate small side shoots or more flowers.

Back to blog