Plants that are prone to bolting

Coriander, wild rocket, mizuna and some other leafy plants are quite prone to bolting in warm, dry conditions. Bolting basically means that rather than producing lots of lovely leaves, they suddenly decide to produce flowers and seeds as quickly as they possibly can. They do this because, for one reason or another, they are no longer able to thrive in their conditions, and so must get the next generation on the go before it’s too late.

As is often the way in gardening, prevention is better than a cure, so we wanted to take a quick look at the conditions under which you can expect to see plants bolt, as well as some ways of preventing it. Hopefully this way you will be prepared and can avoid your plants bolting too early on in the season!

When plants bolt:

  1. A sudden cold spell – just as the plants were getting into the swing of things, a cold spell comes along and tricks them into thinking winter has arrived so they decide to get a wriggle on and get their seeds sown asap.
  2. A hot, dry spell – if the plants don’t get enough water, they can often bolt in response to perceived drought.
  3. Being transplanted – sometimes the shock of being moved from their seed tray to a bed can trigger a plant to bolt. It’s almost as if they have panicked, thinking that they won’t be able to survive in their new home, and so they put down seed instead of growing more leaves.
  4. A change in the number of daylight hours – most often seen in lettuces and spinach, longer days can trigger plants to bolt as well.
  5. General stress – strong winds, for example, can stress plants out, as can damage by pests.

Ways to prevent bolting:

  1. Try to create a consistent temperature and moisture level in the soil to alleviate the problems of hot or cold spells. The way to do this is to add a good layer of mulch around vulnerable plants to keep them from drying out and will help to keep the soil a little warmer on cold days.
  2. Plant vulnerable plants in a spot that gets some morning sun, but a little shade in the hot afternoon sun.
  3. Be sure to water well to keep the soil nice and moist throughout the season.
  4. Protect plants from cold weather at the start of the season with fleece.