If you’re trying to grow cool weather crops like coriander and lettuce in early summer, you’ll probably run into this frustrating problem. You will see the plant close the bolt before it starts.
Certain plants are more susceptible to bolting than others, but there are ways to help your favorite plants last a little longer in your garden (even in mid-July).
What is the bolt?
When the plant bolts it out, it sends the flower stems early before they are harvested. Instead of growing larger leaves, the plant transfers its energy to seed production.
Bolting is sometimes also called “sowing seeds” for this reason. This is a plant bolt as a final groove effort to spread seeds and produce offspring. (This is technically different from plants that naturally sow seeds at the end of their growing season.
When the plant tightens its bolts, it stimulates sudden growth. The flower head appears from the center of the plant, very high (taller than the mature height of the plant), with hard, sometimes woody stems and sometimes woody stems.
Boltongs occur for a variety of reasons, but are especially common in heat-sensitive plants such as lettuce, kale, arugula, broccoli, cauliflower, cabbage and other lush greens. However, it can also occur in root crops such as carrots, beets, turnips, parsnips, rutabaga and radish, resulting in a spike in flowers when the plant is barely developed.
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How to prevent or delay bolting
If you are trying to maximize your harvest, here are some ways (or at least slow it down) that you can prevent your plants from bolting.
1. Directly adjust the seeds.
Certain plants (carrots, beets, parsley, etc.) tend to bolt due to root stress. These plants grow best when they are sown directly into the garden, rather than starting the seeds indoors and then transplanting them outdoors.
Read more: Don’t start these cool season seeds indoors
Direct sowing eliminates all possibilities of implantation shock and allows the root system to develop without interference. (Don’t forget to thin the seedlings.
2. Avoid purchasing or transplanting stressful seedlings.
If you are purchasing most of your seedlings from nursery schools (especially when they are sold in 6 packs), don’t go home with little chance of developing into healthy, mature plants.
How can I know?
Look for sturdy and full seedlings, not tall and thorny stems. I often see brassica saplings already going out as they have small, narrower leaves that grow vertically, and everything is gangbang and wiry.
If you are transplanting your own seedlings that started at home, choose the most compact, lush and healthy saplings over large or taller ones with pale or root bound saplings.
3. Choose a heat-resistant or bolt-resistant plant varieties.
Many cool weather crops (like lettuce and bokchoy) have heat-resistant varieties that have excellent resistance to boltongs. Check the plant’s descriptions for properties such as “heat resistance”, “bolt resistance”, “slow bolt”, and “heat resistance”, especially if you live in warm climates or tend to have unpredictable weather in the spring.
Try these: the best heat-resistant lettuce variety that will grow all summer
4. Plant crops in the appropriate season. Or switch to autumn planting.
Even those that can grow year-round, all plant crops grow in certain seasons, with peak flavor and production during these seasons.
Cool seasonal crops (such as carrots and cabbage) are great for planting early spring or late summer, so they mature while temperatures are still mild. Not only that, but when mature in cold weather, these types of crops actually become sweet! If you have never grown root crops or lush greenery in autumn, or have never harvested after the first frost, you are in for treats.
If you live in an area where warmer spring weather is coming soon, consider growing large amounts of diversity early or starting seeds at the end of winter.
Or start an autumn garden where hot weather and the length of the day (the main cause of bolting) is no problem at all. You can start seeds in the summer at the end of the evening, or transplant the seedlings when the soil is still warm. (If you see some of the hottest days of September when your climate is in September, here are some tips for planting autumn gardens in the heat.)
Read next: The fastest growing crops that can be planted within 40 days
5. Cool the soil with a layer of organic mulch.
Mulch has many benefits to the garden, and one of the most important is to protect the soil and buffer it from heat, cold and temperature fluctuations.
A 2-inch organic mulch layer helps isolate plant roots and keep them cool in hot weather. This reduces the amount of heat stress experienced by plants when air and soil temperatures rise, leading to longer harvesting periods.
6. Consistently deep water.
Providing normal moisture is one of the best ways to protect plants from slow and deep, and heat stress, which reduces instinct.
Long and slow watering also helps the roots penetrate deep into the soil. There you will have access to more water, nutrients and beneficial microorganisms.
Read more: How to properly water your garden during heat waves
Especially on hot days I often water auxiliary (on top of drip irrigation in my garden bed) and give heat-sensitive plants a midday relief.
7. Provide shade in the hottest parts of the day.
In addition to mulch, it is helpful to use row covers or shaded fabrics to keep heat-sensitive plants cool as the weather warms. It is easiest to buy such a roll (providing 40% shade) that can be cut into all garden bed sizes.
They can also be planted in the shade of tall crops or in containers. This allows you to move your cool season crops to shady locations in the afternoon.
8. When the plant is young, use liquid seaweed fertilizer.
The positive effects of seaweed extracts on plants are still under investigation, but recent studies from 2017 to 2021 show that plants treated with extracts from ascofilm improved their resilience to drought and heat stress.
Seaweed extracts also contain many active compounds and trace minerals that help promote plant growth by developing a stronger root system, promoting increased yield and improving resistance to pests and diseases.
What this all means is that using organic seaweed or kelp liquid fertilizers not only help your plants grow, but also helps to withstand extreme heat and recover from environmental stress.
Note that plants should not be fertilized while they are exposed to heat stress.
Can I cut out the stems of the flower to prevent bolting?
Unfortunately, no. It may slow things down a bit, but it doesn’t stop the plant bolts from stopping. After your plant sends the first flower spike, it will not retreat.
An interesting “exception” to this rule are herbs like parsley and cilantro. This is actually productive when you cut out the flowers (and stems) and harvest them frequently. This will allow you to extend your life cycle for months without perceptible changes in flavor or texture.
However, for most plants, even after removing all flowers, they continue to send new flower spikes, slowing down vegetative growth.
When you need to secure the plant with bolts
Bolts are usually a source of frustration if you don’t have much chance to harvest from the plant, but the flowers are still worth keeping.
For one thing, some flower buds (like kale) are edible and even considered delicate. You may not be able to get a full harvest of the leaves, but you can certainly throw some flowers into a salad or stir-fried them!
Secondly, the Bolt plants of the Brassica family (broccoli, kohlrabi, kale, collard greens, etc.) and the Parsley family (parsley, cilantro, fennel, dill, etc.) are paradises for pollinators.
Bees absolutely love these little simple flowers (which tend to grow in clusters called umbels). I say I tend to see more bees in flowering mustard and flowering herbs than in flower garden flowers.
Details: My favorite bee-friendly flowers to plant in every garden
But it’s not just honeybees. Other beneficial insects and predatory insects also eat nectar and pollen. By making these small flowers available, they can be stuck in your garden and naturally control pests.
Make this: Attract good insects in your garden with these simple recipes for beneficial “Bug Butterflies”
And finally, bolted plants give you the opportunity to save the seeds. Most people never save seeds from carrots, beets, kale or collard greens. Because as a biennial plant, it is often harvested before it completes its lifecycle.
However, if they tighten the bolts with the bolts, they can save the seeds from their favorite variety without waiting for them to go through two growing seasons.
This post was updated from an article originally featured on June 29th, 2023.
