In the garden, of course we want all of our harvests to be successful. However, sometimes things beyond our control, such as the weather can impact our crops. Bolting can happen to a variety of plants in the veg garden, so here’s all you need to know about it…
What is bolting?
Bolting occurs in the vegetable garden and refers to when plants set seed early, making them inedible or unusable. It can be spotted when the plant starts to elongate and produce stems or flowers before the crop is ready for harvest.
The crops become bitter tasting, or poor quality, no good for use in the kitchen. This can happen due to cold spells, changes in temperature and change of day length.
Plants that bolt
Bolting can impact a wide range of vegetables in the garden. Lettuce, fennel, spinach, leeks, carrots, pak choi, and onions can all be impacted.
Annual crops such as lettuce, spinach and some radishes are sensitive to how many hours of daylight they get. These are both cold-season plants, so don’t enjoy hot weather. Therefore, if there are long spells of dry, hot weather, the chances of bolting are increased.
They begin the process of setting seed as the days get longer. So it’s normal for this to happen in summer, but it can happen prematurely.
Lettuce can bolt very quickly too. In fact, it can take just a couple of days.
On the other hand, biennial crops grow in the first year and flower in the second. This includes crops such as onions, leeks, carrots, and beetroot. However, adverse weather conditions or a quick change from cold spells to warmer weather can lead to flowers in the first year.
Keep under control
There are a few steps to take to reduce the likelihood of bolting. Adapting sowing times and knowing your soil type can have an influence on the chances of bolting. Certain plants are very sensitive to cold weather. Therefore it’s ideal to wait until temperatures are more stable in April or May to sow. This is a useful tip when growing Swiss chard.
With sensitive biennial vegetables, give them the best start by sowing and growing in a greenhouse or under the protection of a cloche or polytunnel. It’s also ideal to sow successionally so there is a continual supply of crops to be harvested through the season. This will stop you from leaving the harvests too long and with the potential to bolt.
Giving plants shade from the sun to guaranteeing lower temperatures, will increase moisture retention. By protecting plants from long, hot spells it’ll reduce the risk. Shade plants like lettuce by positioning a wire tunnel or structure and draping shade cloth over it.
In the same way, keeping on top of watering and mulching can have a good impact. Don’t keep your plants thirsty by ensuring there is sufficient mulch around them to keep water and nutrients in rather than letting it dry out quickly.
Over time, cultivars have been specifically bred to be resistant to bolting. For instance, ‘Boltardy’ is a well-known bolt-resistant beetroot that can be sown from March until July in a sunny spot. For a constant supply of the crops, sow seeds every two weeks from March onwards. The harvests will be good to go between June and October, with a tender texture and sweet taste. Not only that, but the young leaves of the plant can be used in salads through the season to make the most of the crop.
Similarly, ‘Slobolt’ is a variety of coriander that has a reliably good flavour due to it being slow to bolt, as its name suggests. This herb is a worthwhile addition if you want to avoid the risk of bolting. It will grow happily in a container as part of your larger herb garden.
Spinach ‘Amazon’ is a fast-growing variety that has a good resistance to bolting, however keep them well-watered to ensure this doesn’t happen. Sow the seeds outdoors from April until August, for harvests of dark green, glossy leaves that can be added to sandwiches, salads, curries, and a whole host of meals for a flavour boost and a nutrition kick.
Bolting can impact your vegetable plot, but there are steps you can take before and during growing season to decrease the likelihood of it happening. With bolted plants, add them to your compost heap and use the space to grow something new!
David Domoney is a Chartered Horticulturalist, Broadcaster, and Author. David has worked with a number of the UK’s leading garden retailers as a plant buyer and strategic consultant. With more than 30 years experience, in horticulture, David is as passionate about plants now as he was when he bought his first plant at a village fete.
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