Fill a plant pot with two parts organic potting soil and one part compost. The pot should be at least 8-inches wide and have drainage holes in the bottom.
Insert the bok choy seed into the pot at a depth of 1/2 inch. Water until the soil settles. Continue watering frequently enough to keep the soil evenly moist to the touch, which will result in tender plants.
Set the pot in a window that gets full sun. Keep the pot out of hot or cold drafts. Keep the temperature below 75 degrees F. Move the plants out of the window after they have been in full sun for 8 hours.
Cut the heads off 50 to 80 days after you planted them, before they go to seed. Cut them off at the soil level.