Bolting (horticulture)

Bolting, in horticulture, refers to the premature production of a flowering stem (or stems) on a plant, generally in crops grown for their leaves or roots. This flowering is usually accompanied by a rapid elongation of the stem, often resulting in a change in the plant's flavor and texture, making it undesirable for consumption.

Bolting is often triggered by environmental stresses, particularly high temperatures or long day lengths (photoperiod), signaling to the plant that it is time to reproduce before conditions become even more unfavorable. Some plant species are genetically predisposed to bolt more readily than others.

The impact of bolting varies depending on the plant. In leafy vegetables such as lettuce, spinach, and arugula, bolting makes the leaves bitter and tough, rendering them unpalatable. In root crops like carrots, beets, and radishes, bolting diverts energy away from root development, resulting in smaller, woodier, and less flavorful roots.

Preventative measures against bolting include selecting bolt-resistant varieties, providing adequate water and nutrients, and shading plants during periods of intense heat. Planting at appropriate times of the year, taking into consideration day length and temperature fluctuations, can also help to minimize the risk of bolting. Row covers or shade cloth can further mitigate the effects of environmental stress.