my kohlrabi plants look great--70 days out from planting, but very few plants have "fruit" set on. Ate 1--delicious, but. . .
Certified GKH Gardening Expert
These need extremely fertile, moisture-retentive soil, so you may want to add compost, or fertilizers before planting. They also prefer cooler weather, either spring or fall. This article will give you more information on the care of these: https://www.gardeningknowhow.com/edible/vegetables/kohlrabi/how-to-grow-kohlrabi.htm