Growing Bok Choy
Soil should be well drained, rich, loose and fertile with a Soil pH of 6.0 – 7.5. Ample mature compost is advisable prior to planting. Organic fertilizer heavier in nitrogen and less phosphorus is best after thinning or transplanting.
Bok choy requires ample moisture to thrive and prevent premature bolting. Keep the soil moist with regular, even watering, usually about an inch weekly. Use heavy mulch which helps moisture retention in the soil, repels some insects and suppresses weeds.
Most varieties of bok choy should be harvested while the plant is not fully mature, generally 12 – 18 inches in height, and as early as 6-8 weeks from sowing, although this varies slightly from variety to variety. Bok Choy grown hydroponically can be harvested in as little as 30 days. Harvest the entire plant instead of leaf by leaf. If the weather becomes excessively hot, harvest early .
You can also get multiple harvests from one planting. Cut just above the soil line when harvesting individual stalks. The roots still in the ground will produce a new head initiating from the center. After the first harvest the plant becomes less robust and the harvestable heads are not as big as the first - but hey two heads are better than one. After the third harvest the season is usually exhausted as is the plant.
The primary difference between most types of bok choy is the head size. Smaller varieties are sweeter and more tender, while the larger, dark green varieties are more common among westerners. There are over 20 varieties of bok choy, with varying characteristics.
Gai lan is not really Bok Choy but a close cousin, it is dark-green and more bitter if eaten raw. It is sometimes called Chinese Broccoli.