As soon as the soil can be worked, sow 1 seed per inch, 1/2" deep, in rows 18" apart, thinning to 6" apart. Allow 2 weeks for germination. When the bottom of the bulb has reached 2-3" in diameter, it is ready for harvest. A packet contains 100 seeds and sows about 10' of row.
We also have starter plants available for Kossak Hybrid Kohlrabi