How to Manage Pests

Pests in Gardens and Landscapes


Bolting occurs when flowers develop too quickly. The plant begins to grow tall and sends up flower stalks.


Bolting is caused by prolonged cold temperatures, hot temperatures, or long daylight hours. Plan to plant when environmental conditions during development will not stimulate bolting or the growth of flower stalks. Choose varieties carefully.

Lettuce: Flower stalk initiation may be stimulated by high temperatures.

Spinach: Bolting is caused by long daylight periods from late spring to early fall.

Cole crops: For seeds planted in the spring, flower stalk initiation is stimulated by prolonged cold temperatures below 50°F. For fall-planted seeds, plants may bolt if they start to grow quickly and are then forced to slow down by cold temperatures. Bolting cannot occur until plants have received the cold chilling in the winter.

Bolting of broccoli
Bolting of lettuce plant

Bolting of broccoli
Bolting of spinach plant

Statewide IPM Program, Agriculture and Natural Resources, University of California
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