Bok choy, a type of Chinese cabbage, is a popular cool-season vegetable prized for its tender leaves and crisp stalks. Gardeners often see the plant send up a tall stalk topped with yellow flowers, a process known as bolting. This premature flowering shifts the plant’s focus from producing edible leaves to reproduction, raising the question of whether the flowers should be cut or the entire crop harvested. Understanding this natural biological process is the first step in managing your harvest.
Why Bok Choy Starts to Flower
Bolting is the plant’s physiological shift from vegetative to reproductive growth, dedicating energy to producing flowers and seeds. Bok choy, a member of the Brassica family, is highly susceptible to this process, which is primarily triggered by environmental stress. The most frequent cause is temperature fluctuation, specifically a sudden warm spell or sustained high temperatures above its ideal range of 60°F to 68°F (15°C to 20°C). Environmental pressures, such as drought, inconsistent watering, or root stress from overcrowding, can also signal the plant that its survival is threatened, prompting it to reproduce quickly.
Immediate Action: Cutting or Leaving the Flowers
When a flower stalk first appears, the immediate action depends on the plant’s stage of bolting. If the main stalk is just starting to emerge from the center, cutting it off at the base can occasionally delay the full process. Removing this stalk may force the plant to produce side shoots, offering a few more small, edible leaves for a short time. However, this technique will not stop bolting entirely. If the plant is heavily bolted, the better option is to harvest the entire plant immediately or leave it to fully flower if you wish to collect seeds later.
Edibility and Flavor Changes After Flowering
The bolting process significantly impacts the flavor and texture of the bok choy leaves. Once a plant bolts, the leaves become tougher and develop a noticeably stronger, often bitter taste due to an increased concentration of alkaloids. Harvesting the remaining leaves quickly, as soon as the first signs of bolting appear, can help salvage the best flavor. The flowers and young flower stalks, however, are completely edible and quite tender. These small, yellow flowers have a mild, slightly sweet, mustard-like flavor and are excellent additions to salads or stir-fries.
Preventing Early Flowering in Future Crops
To maximize the harvest of tender leaves, focus on minimizing plant stress and managing the growing environment. Plant at the correct time to avoid extreme temperatures, sowing in early spring or late summer so the crop matures before high heat. Providing consistent moisture is also effective, as drought stress is a common trigger for bolting; the soil should remain consistently damp, requiring about one inch of water per week. During periods of high temperatures, providing temporary shade with a shade cloth can help keep the plant cool. Selecting a bolt-resistant variety of bok choy provides an additional layer of protection.