Bolting on Plants

Symptoms

Bolting happens when flowers develop too quickly. You may also see this called premature flowering. The word describes a plant that moves toward flowering faster than it should.

As this happens, the plant begins to grow tall and sends up a flower stalk. The plant grows unusually tall. A strong central stem rises so that the plant can produce seed.

The leaves also become bitter. A bolting plant changes in the way it grows and in the state of its leaves. Bolting cannot be reversed once it has started. For that reason, the treatment advice is to remove and compost plants once they have bolted.

Lettuce, spinach and radish are among the crops named for this problem. Premature flowers, a tall flower stalk, a strong central stem and bitter leaves are the signs that describe it. Each of these signs comes from the same problem, which is bolting.

Causes

Several conditions can cause bolting. The causes recorded are prolonged cold temperatures, hot or high temperatures, and long daylight hours or changes in day length. Dry soil or drought stress is also a cause, as is overcrowding from failing to thin seedlings.

Temperature can push a plant to bolt in two ways. Prolonged cold temperatures can cause bolting, and hot temperatures can cause it too. Neither extreme is the only trigger on the list.

Light is another cause. Long daylight hours can cause bolting, and changes in day length can trigger it.

Water supply is also involved. Dry soil or drought stress can make a plant bolt from drying out. The matching advice is to keep soil consistently moist so plants do not bolt from drying out.

Crowding is the last cause on the list. Seedlings that are not thinned can become overcrowded, and overcrowding leads to premature bolting.

Cold, heat and day length are conditions of the environment. The treatment advice is to plan planting for a time when conditions during development will not stimulate bolting or the growth of flower stalks.

Diagnosis

Start with the shape of the plant. A bolting plant begins to grow tall and sends up a flower stalk. If your plant is unusually tall and has a flower stalk, it fits the description of bolting.

Next, look at the center of the plant. Bolting plants send up a strong central stem to produce seed. Leaves that have become bitter are one more sign of bolting.

The recorded causes give you a checklist: prolonged cold, hot temperatures, long days or changing day length, dry soil, and crowded seedlings. Each of them is a recorded cause of bolting.

Bolting is defined by flowers developing too quickly. A plant with no flower stalk and no central stem is not showing the symptoms listed for bolting. This page lists no other signs for bolting, so judge the plant against the ones above.

The crop matters too. Check whether your plant is a crop such as cilantro, cabbage, celery or beet. Bolting cannot be reversed, so a confirmed case is a plant to remove and compost.

Treatments

The treatments on record for bolting are all cultural methods. Bolting cannot be reversed, so most of these methods are about stopping it before it starts, and one covers what to do afterward. Of the six methods, five aim to prevent bolting and one deals with plants that have already bolted.

Plan your planting for a time when the conditions during the plant's development will not stimulate bolting or flower stalk growth. The environment that matters includes temperature and day length, the conditions named under causes. Choose varieties carefully, and select slow-bolting or bolt-resistant cultivars.

Keep the soil consistently moist so plants do not bolt from drying out. Thin seedlings to proper spacing to reduce premature bolting from overcrowding. Spacing and moisture are two of the causes listed above, and these two methods answer them directly. Thinning matters because failing to thin seedlings, which causes overcrowding, is a recorded cause of bolting.

Use succession planting, and time your harvest to the crop's cool-season window to avoid bolting. Cool-season timing is the link to the temperature causes listed earlier: prolonged cold and hot temperatures can both cause bolting.

If a plant has already bolted, remove it and compost it. Bolting cannot be reversed, which is the reason given for removing and composting the plant. The facts on file list no organic or chemical treatments for bolting.

Prevention

The conditions that cause bolting are cold, heat, day length, dry soil and crowding. Prevention means keeping those conditions from building up during the plant's development.

Timing is one condition to get right. Plant when conditions will not stimulate bolting, and match the harvest to the cool-season window of the crop. This applies to lettuce, spinach, radish, cilantro, cabbage, celery and beet.

Moisture is a condition too. Soil that dries out can lead to bolting, so a steady supply of water matters.

Spacing is another condition. Thin seedlings to proper spacing, because overcrowding is a recorded cause of premature bolting. Variety is a further choice to make with care, and slow-bolting or bolt-resistant cultivars are the ones to select. Together these conditions are timing, variety, moisture and spacing.

Plants most often affected

The crops recorded as affected by bolting are lettuce, spinach, radish, cilantro, cabbage, celery and beet. On these crops, bolting looks like premature flowers, a tall flower stalk, a strong central stem and bitter leaves. Beet is one of the listed crops, and bolting beet plants are recorded as a case of the problem.

No plant page in this build records this problem yet.