Cabbage is a nutritious, leafy green vegetable with a long growing season. It can grow in both the spring and the fall, and it can tolerate a range of temperatures and conditions. Cabbage does take a fair bit of room to be grown indoors, but the outcome is worth it if you have the space. Plant a variety of cabbages with different growing periods, and you will have cabbage available for months at a time.
Get a planter that is about 10 inches deep, 12 inches wide and the largest length-wise that you have room for. Put a layer of gravel on the bottom, and set the whole planter on the drip tray.
Fill the planter with rich, loamy loose soil. Mix in continuous-release vegetable food according to the instructions on the package.
Place a cluster of three cabbage seeds separated by about three inches every 12 inches. For example, if your planter is 36 inches long, plant two clusters of seeds with their centers 12 inches apart and 12 inches from either end. Cover the seeds with half an inch of soil, and put a toothpick between them to mark the location.
Place the planter in the sunniest part of the room. The more sunlight the cabbage gets, the better.
Water the plants every day, keeping the soil moist but not drenched.
After about six weeks, remove the two scrawniest or weakest-looking plants from each cluster. By this point, the cabbage heads should be developed.
Add 20-20-20 fertilizer to the soil when the cabbage starts to form its head. Add as much fertilizer as the package recommends. 20-20-20 fertilizer is made up of 20 percent each of potassium, nitrogen and phosphorous.
Harvest the cabbage when the head is firm and fully formed. Gently squeeze the head to test. If it is still soft, the cabbage is not ready. This will take anywhere from 60 days to more than 100, depending on the type of cabbage planted.