Tony O’Neill, gardener and author of the popular “Composting Masterclass” and “Your First Vegetable Garden,” combines lifelong passion and expert knowledge to simplify the art of gardening. His mission? Helping you cultivate a thriving garden. More on Tony O’Neill
‘Bolting’ refers to running away. And while plants cannot essentially run away, bolting is, in fact, the plant’s survival mechanism that is triggered when it experiences stressful conditions. The term is used for plants beginning to flower and setting seeds too early, preventing the plant from bearing a vigorous harvest.
It will bolt if the plant is under stress, like extreme temperature changes, changes in day length, or any other strain. It will then focus on producing the next generation (seeds and flowers) rather than growing leaves, roots, or stems.
Broccoli, cilantro, basil, cabbage, and lettuce are some plants known for bolting. Once a plant bolts, it becomes woody, tasteless, or bitter, leaving vegetables inedible. However, delaying or temporarily reversing the bolting process is sometimes possible.
Let us now discuss the various reasons that can cause vegetables to bolt and some ways to prevent or postpone bolting.
Reasons for Bolting in Plants
As mentioned, plants bolt in response to stressful and unsuitable weather conditions. It should also be said that annual crops flower naturally in the first year. On the other hand, biennials typically do not flower until the second year.
In biennials, bolting occurs when an over-wintering organ flowers before the winter. This usually happens with carrot roots. And in annual crops, bolting usually occurs before they are ready to gather. Moreover, some other reasons are responsible for the plant to bolt:
· Increased Day Length
As summer approaches, the days get longer, and exposure to sunlight also increases. This can potentially damage garden plants, especially annual crops. Also, cool weather crops such as lettuce and spinach will bolt in hot and dry spells. Moreover, this can also increase the soil’s temperature, further triggering plant bolting. This is usually a problem observed in plants grown too late in the spring.
· Cold Temperature
While increased day length and excessive heat can damage cold weather crops and annuals, cold temperatures can also harm biennials like onions, leeks, beets, and carrots. A sudden cold snap during spring can signal the plant that the winter season has commenced, triggering bolting.
So, if you grow these plants way before the spring season, you will expose young seedlings to cold temperatures, damaging them.
· Root Stress
Transplanting can quite often disturb the plants’ root systems. Other than this, growing a plant in a smaller container can also cause root stress which can, in turn, lead to bolting. Thus, it is essential to ensure that you pick the right pot for your plant and take proper care while transplanting it.
· Plant size
It is usually observed that larger plants are more likely to bolt than small ones in unsuitable weather conditions or temperatures.
· Insufficient Mineral or Water Supply
As we all know, soil rich in nutrients and balanced moisture levels promotes the healthy growth of plants. Thus, an imbalance, particularly during summer, can cause the plant to bolt. Also, increased salt levels in the soil can stress the plant, especially in structures like hoop houses.
Some more susceptible plants to bolting are cauliflower, rocket, and spinach. This is when they do not get enough moisture.
To ensure that your soil has balanced moisture levels, you should ensure that your garden gets at least one inch of water in a week. You can further increase the amount if you have sandy soil. Also, if the weather gets warm, you should ensure the soil is soaked in water to ensure the plants are not stressed.
Ways to Prevent Your Plants from Bolting
There are quite a few things that can help prevent bolting. This is extremely important since once it has started, it can be impossible to stop it. You can try multiple methods to ensure your plants are not stressed and increase your chances of having a healthy and bountiful harvest. Here are a few ways in which you can avoid bolting and encourage a healthy growth cycle:
1. Grow Bolt-Resistant Varieties
Growing “bolt-resistant” or “slow bolting” seeds is one of the easiest ways to decrease bolting significantly. All you need to do for such labels are the seeds that have developed resistance to conditions that may cause bolting.
For instance, you should seek heat-treated onion sets to grow onions. These varieties can withstand high temperatures and are much more unlikely to bolt. Also, one should avoid red onions, which are usually more prone to bolting than white or brown varieties.
2. Use Mulch
Usually, plants like broccoli, cauliflower, and cilantro have heat-sensitive roots, making them more susceptible to bolting. One can consider spreading a layer of mulch to prevent the soil or roots from overheating. This would keep the topsoil cool and help in locking in moisture. A gardener should not have bare soil in the garden unless seeds are about to germinate in a newly planted bed.
Suppose you have no idea about using mulch. I have a video about garden mulch ideas. You can watch it below.
3. Plant During Cooler Months
Growing a plant in early spring can still be warm in some regions. Thus, it is essential to consider your local climate before sowing the seeds. Also, you can try growing spring vegetables in the fall. This is when hot temperatures are not usually expected. You can grow brassicas such as kale, cabbage, and bok choy during spring or fall.
4. Offer Shade for Cold-Weather Crops
As mentioned, growing plants in hot-weather climates can overheat the soil and roots. This would require you to ensure that the plants get enough shade. While this is primarily for your cool-season crops such as spinach, lettuce, and radishes, vegetables, like exposure to sunlight, may also bolt if the weather is extremely warm or dry. So, it is vital to offer them natural shade.
Planting these crops near taller plants can be a great trick. You may even consider planting them in garden beds in an area located in partial shade. Or you may even use draping shade cloth over them.
5. Use The Right Fertilizer
If you wish to treat their crops with fertilizer, you must ensure that it is customized to your needs, i.e., growing leaves and stems. This will ensure that the plant is not encouraged for flower growth. For this, you would need a fertilizer with a high level of nitrogen content.
6. Avoid Transplanting
As mentioned, certain plants such as carrots, turnips, beetroot, radishes, and herbs are prone to bolting due to root stress. These tend to grow the best when they are sown outdoors directly. So, it is better to avoid transplanting them, which is often associated with root stress. This will ensure that your plants grow without any disturbance.
How to Identify Bolting?
To prevent your plants from bolting, you first need to identify the first signs of it. And the good news is that it is easy to do. The bad news is that once you have identified bolting on a plant, it is too late to do much about it. Here are a few things that you may notice when a plant is bolting:
- Tough talk with only a few leaves
- The rapid and upward growth
- Stalk starts to form buds that first become flowers, followed by seeds
- The slow rate of edible and vegetative growth
- Less desirable taste (bitter and unpalatable) of the remaining leaves
However, there are chances that it is already quite late, and you might not be able to do a lot to stop it. But one can always try and temporarily reverse the adverse effects of bolting by harvesting often and pinching off flowers.
What to Do When Plants Bolt?
Plants usually bolt, and it is not much you can do about it. So, if your plants bolt even after trying the abovementioned methods, you must understand that this is not the world’s end. You can still do quite a few things to help you make the most of your plants.
You may still be able to rescue some of the leaves (peppery arugula or slightly bitter lettuce) by mixing them with other salad greens. Some people prefer the taste of it over the bland-tasting lettuce available in the market. You can also chop up root vegetables and use them in stews. And when it comes to onions and leeks, you can usually chop out the usable parts and use them.
While you cannot control the climate or the weather conditions, changing your attitude is relatively easy. Other than using the remaining veggies, it would help if you were pragmatic. One should learn to appreciate all the goodness that it can offer.
Bolted vegetables are often thought to be useless. However, they can be a boon for pollinating insects like bees. Consider them to be a feast for them while they also offer your garden some attractive blooms. Some of the most eye-pleasing ones are said to be the bobbing globes of alliums, lace-like carrot umbels, and yellow brassica flowers.
Also, according to some, flowering bok choy stems pretty sweet and tender, which would make for an excellent ingredient for stir-fry dishes or salads. This is why some gardeners often let vegetable plants flower for a little while before getting them out and planting a new crop.
FAQs on From Bolting to Beautiful Transforming Your Vegetable Garden
Can you eat lettuce after it bolts?
It’s possible to pick and eat bolted lettuce. However, if the leaves are left on the plant for too long, they will turn bitter and unpleasant, so pluck the leaves as soon as possible after lettuce bolting and remove the entire plant once all edible leaves have been plucked.
What do you plant after lettuce bolts?
For most gardeners, Bush beans are the most delicate vegetables to plant after lettuce. Carrots, cucumbers, squash, and the second sowing of basil are all beautiful vegetables to grow, following lettuce to see you through the summer.
Will lettuce regrow after cutting?
If routinely watered after clipping, head lettuce will die back, but most leaf lettuce plants will restart their efforts to produce leaves. Although the crop will usually be smaller than the first, you may be able to harvest a second, tasty crop in as little as two weeks.
Conclusion on what causes vegetables to bolt
A gardener should understand that every plant has the genetic prerogative to make seeds. They react differently to different climatic changes. So, when a plant starts bolting, knowing this has nothing to do with your gardening skills is essential.
One of the best ways to prevent it is by learning how mother nature works and going with it. Plan to grow cool-season plants in the cool season and not delay when they peak freshness and health.
We are sure that at least one of these tips will help you make the most out of your plants and help you delay, if not prevent, bolting.