Winter in Zone 9 can range from down-right-cold to mid-summer warm. Lettuce is a plant that does not like the warmth that can occur in Zone 9, and will almost always bolt to seed at first sign of temperatures above the low to mid 70s. While this is bad news for lettuce lovers, there is good news; there are a few techniques to help avoid bolting.
Grow Lettuce in the Shade
Knowing that there is a good chance for warmer temperatures here in zone 9 it is a good idea to grow lettuce in an area of the garden that receives a good amount of shade through out the day. This reduced direct sun will not only help keep the temperatures down, but the reduced amount of direct sun also has a direct effect on lettuce bolting to seed. If a shady spot is not available, shade cloth above the plants will work well, and can be removed during cooler times!
Keep the Soil Well Watered
Keeping soil moist will help reduce the temperatures of the roots and the air closest to the soil. During the warmest parts of the winter, it can be helpful to water the lettuce up to twice a day to keep the temperatures down. Be careful to not over water as most types of lettuce are susceptible to root rot.
Choose Slow-to-Bolt Varieties
There are many types of lettuce available in seed catalogs and some of them are slow to bolt. These varieties are more resistant to warmth and will bolt to seed much slower. They are often named in a way that would suggest their bolt resistance, such as SloBolt.
Using the 3 above techniques in combination can lead to a bountiful harvest of lettuce deep into the warmer parts of spring!
