How to Avoid Bolting in Plants
It’s that time of year when my friends start asking me why their delicious lettuces and herbs are all the sudden two feet tall and bitter tasting. This, my beautiful gardeners, is called bolting, and it’s a natural part of a plant’s life cycle.
Bolting is when a crop that is normally used for non-flowering parts, such as leaves or roots, sends out a flower stalk in an attempt to reproduce. When this happens the plant stops putting energy into growing the parts that we like to eat, like leaves of lettuce or cilantro.
Plants that are susceptible to bolting are lettuces, herbs like cilantro and dill, spinach and beets, and brassicas like cabbage, kale and mustard.
Bolting generally happens in response to triggers like day length, changes in air and soil temperatures, or even to stresses like drought and soil mineral deficiencies.
You can use these tips to prevent bolting:
- Plant at the correct time of year for best day length and temperatures – start planting as soon as the soil is within the temperature range for germination
- Keep plants watered – especially lettuces
- Use bolt-resistant cultivars/varieties
- Pinch off flower stalks before the plant sets seeds
- Use a 40% shade cloth to keep plants cool
- Put plants closer together so the soil stays shaded and cooler when the canopy closes
- Use succession planting – and start your seedlings inside so you can both prevent temperature fluctuations that set off bolting and also allow maximum production from your growing space
Bolt Resistant Plant Varieties
- Southern Exposure Seed Exchange Info – great information about extending lettuce into the warm season – http://www.southernexposure.com/lettuce-ezp-61.html
- Batavian types such as: loose leaf, semi-heading, crisp, good shelf life after harvesting
- 40-80F soil temp for germination
- Slo-bolt cilantro – http://www.rareseeds.com/cilantro-slo-bolt/
- 55-68F soil temp for germination
- Renegade F1 spinach – http://www.highmowingseeds.com/organic-non-gmo-seeds-Renegade-F1-Hybrid-Spinach.html
- 40-75F soil temp for germination
- Greensleeves dill – http://www.highmowingseeds.com/organic-non-gmo-seeds-Greensleeves-Dill.html
- 60-70F soil temp for germination