Standard kohlrabi sun requirements call for 6-8 hours of direct light each day. Alabama Extension lists this range as ideal for good bulb growth. But kohlrabi handles less sun better than most vegetables in your garden.
I tested this in my own garden with two rows of the same variety. One row got full sun all day. The other sat behind some taller plants and only got about 5 hours of direct light. Both rows made decent bulbs but the full sun plants grew 20% larger by harvest time.
Kohlrabi light needs connect to how the plant builds its swollen stem. More light means more energy for growth. The plant uses that energy to pack sugars into the bulb. Less light slows this process down but does not stop it like it would for tomatoes or peppers.
Growing kohlrabi in shade works better than you might think. Partial shade keeps soil cooler in hot weather. Cool soil helps kohlrabi avoid stress that causes woody or bitter bulbs. A few hours of afternoon shade can save a summer crop from heat damage.
I now pick my planting spots based on the season. Spring kohlrabi goes in my sunniest bed to push fast growth. Late spring crops get a spot with afternoon shade to stay cool as temps climb. Fall plantings go back to full sun when cooler weather returns.
Watch your plants for signs they need more light. Leggy stems that stretch toward the sun mean they want more. Slow bulb growth after several weeks suggests a light problem. Leaves that turn pale green are crying out for sunshine.
Good kohlrabi growing conditions balance light and heat. Aim for 6 hours minimum in cooler climates where heat is not a worry. Cut back to 4-5 hours if summer temps climb above 80°F (27°C) in your area. The shade trade off is worth it to avoid ruined crops.
You can also use shade cloth to manage light levels. A 30% shade cloth blocks some rays while still letting enough through for growth. This gives you control even in beds that get scorching sun all day. Many commercial growers use this trick for summer brassicas.
Match your light setup to your local weather and you will grow great kohlrabi every time. Track your results each season and adjust as needed. The perfect spot in your garden might shift with the calendar.
Read the full article: Growing Kohlrabi: Beginner-Friendly Guide
