>> my plants always bolt right away! I haven't figured out when and how to start bok choi to get veggies instead of bolting to seeds!
Bummer! Unless you want to grow microgreens. Then vast quantities of seeds are good to have for the next sowing, even if they have more than one pollen parent.
Consider that they like uniform moisture, on the moist side rather than the dry side. And they like cool or cold weather. many varieties are pretty frost-tolerant!
A cold-tolerant bok choy ought to grow long enough to eat before bolting even direct-sown before the first frost. Maybe besides sowing a test row a few weeks earlier, and again a few weeks later, and trying a fall crop, you could try different varieties.
If what you have now is heat-tolerant, try a cold-tolerant variety. And vice-versa.
If you have a short or unsettled spring, and it's tricky getting a crop in between frosts and summer heat, try an early variety, or a dwarf variety that matures quickly, or expect to harvest a standard variety well before maturity.
Sowing thickly, then frequent "cut-and-come-again" cycles might defeat the bolting urge for a while, and produce very tender young leaves. They are more tender and sweet before maturity, anyway.
(I didn't push to grow early because my spring stays WET longer than it stays cold. And my summer is so mild that I can grow cool-weather crops into most of the summer.)
I guess they all give up in hot summers. Even "heat tolerant" Brassica greens are still cool-weather crops and cold-weather crops - just some varieties are RELATIVELY heat-tolerant for their genus.
So it's possible for Bok Choy to be PNW-heat-tolerant, but not Texas-heat-tolerant.
If you want greens guaranteed not to complain about cold, try tatsoi!
However, if you're trying to start growing Asian greens with Chinese cabbage in the narrower sense of "Napa cabbage" or "Michihli cabbage", I think others have observed that they are fussy about start times, temperatures and dayength. Having them bolt quickly might not be as surprising.
Not particularly cold-tolerant OR heat-tolerant, eager to bolt, AND day-length-sensitive. I bet Napa and Michihli do take some experimentation in every different micro-climate. Probably it's easier to meet their demands in the fall rather than the spring. And always be ready to harvest them as baby leaves or young salad if they threaten to bolt.
Spring crops of Chinese cabbage (Napa & Michihli) might demand transplants depending on the daylength, duration and settled-ness of your spring. I haven't gotten into that yet.
