Home and Landscape

Bolting

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

Solutions

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.

Overmature head lettuce bolting to flower stage in backyard garden , staged photo. Davis CA. by JKC   Credit: Jack Kelly Clark, UC IPM
Bolting of lettuce plant. Credit: Jack Kelly Clark, UC IPM
Spinach, Spinacia sp. (Chenopodiaceae), bolting or flowering at UC Davis student farm. by JKC.   Credit: Jack Kelly Clark, UC IPM
Bolting of spinach plant. Credit: Jack Kelly Clark, UC IPM
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