Why Lettuce Tastes Bad When it Bolts

Lettuce is a wonderful salad green - but when it decides to make flowers, this otherwise tasty vegetable becomes inedible in a matter of days.

Lettuce is easy to grow and is wonderful in salads and sandwiches - but once it bolts (begins to change so that it can form flowers), the delicious leaves start to taste awful. I this article I will explain why the taste becomes so bad, and discuss how that lettuce can still be eaten and enjoyed.

What is “bolting”?

For annual greens like lettuce, at some point during the growing season after the plants have gathered enough energy, and the days are a certain length, and the soil is a certain temperature, a process becomes triggered that is like the flipping of a switch. When this happens, the plant changes its focus from one of vegetative growth (leaves and stems), to reproductive growth (flowers and seeds). As a result of this transition, the plant undergoes changes in its chemical composition that makes its leaves bitter.

When your lettuce starts reaching for the sky and behaving like flowers - it’s bolting!

One of the main compounds responsible for the bitter taste is called Lactucin, which increases as the plant approaches flowering. Lactucin and other compounds like oxalic acid act as a natural defense mechanism to deter animals and insects from eating the flowering plant. This makes sense because while a plant still needs its leaves during seed production (leaves are what gathers energy from the sun after all), it is really not as invested in leaf generation as it was prior to flowering, so it needs to hang on to the leaves it has.