It’s hard to know exactly when kohlrabi is ready to harvest. Unlike tomatoes or other fruits, you can’t just go by appearance or by feeling if they’re soft. It’s not intuitive, and I believe it’s something you gain from experience from growing kohlrabi. But there are some simple guidelines you can follow to know you’re not picking an overly mature, woody kohlrabi.
Kohlrabi can be harvested when it is at least 2 to 3 inches (5 to 7.6 cm) in diameter. However, this depends on the variety, and some can get quite large. Kohlrabi left too long to mature, well beyond its days to maturity (which can range from 50 to 70 days) can get woody and be of lower quality. Environmental stress and lack of space or nutrients can affect bulb size.
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How Long After Planting Kohlrabi Can I Expect a Harvest
Kohlrabi is typically ready to harvest around 50 to 70 days after transplanting, depending on the variety. Generally, small- to medium-sized kohlrabi don’t take as long to mature as large ones, like the gargantuan Superschmeltz kohlrabi which can reach up to 10 lbs.
Another thing to consider is the time of planting. If you plant late in the season, kohlrabi will grow more slowly because of the shorter days. If you plant early in the season, longer and longer days with more sun will accelerate the growth of your kohlrabi.
If you want to know more about growing kohlrabi from seed, I’ve already written about that in more detail.
Growing Kohlrabi in Fall vs. Growing Kohlrabi in Spring
You can either grow kohlrabi in the fall or grow it in the spring. There are benefits to both, although many gardeners prefer fall kohlrabi.
In early spring, when you plant kohlrabi, the garden is still mostly bare and pest pressure is low, which means you are unlikely to lose your kohlrabi to cabbage worms. Also, this means you will be harvesting kohlrabi in late spring or early summer, giving you space to plant or transplant your summer crops. But mature kohlrabi bulbs, if left too long, can get woody, especially in the high heat of summer.
If you have a long spring with mild summers, spring-planted kohlrabi can thrive easily.
In my area, we get maybe a few weeks of spring and then the hot summer weather kicks in. Kohlrabi grows best in cool weather, and a late fall harvest of kohlrabi is usually the sweetest in flavor, which is why I prefer growing it in the fall. In my case, I sow my seeds indoors in the middle of summer, transplant in late summer
When Is Kohlrabi Ripe?
Kohlrabi technically doesn’t ripen. It’s neither a fruit nor a root. The “bulb” is just the stem of the kohlrabi plant which swells into a around ball.
When to Harvest Kohlrabi
Since kohlrabi doesn’t “ripen”, you can harvest kohlrabi at any time. However, if you leave mature bulbs to keep growing well beyond the estimated days to maturity, they may get woody.
General guidelines suggest harvesting when the kohlrabi bulb is around 2 to 3 inches (5 to 7.6 cm) in diameter, but this can depend on the variety. Some kohlrabi can get up to 10 inches (25 cm)!
For better flavor, harvest kohlrabi early in the morning, as tastes sweeter while it’s cool outside.
Time Your Fall Kohlrabi for the Best Flavor
If you know the approximate days to maturity for your specific variety of kohlrabi, you can take your average first fall frost date and count backwards, then plant around that date. This will guarantee your fall kohlrabi matures when it’s nice and cool, but not completely frozen. Kohlrabi is frost hardy and will survive light frosts (and actually taste better after one).
How to Harvest Kohlrabi
Harvesting kohlrabi is very easy. You can either grab from the bottom of the bulb and pull out the plant, or take garden scissors and cut it off at the root.
Although people grow kohlrabi for the bulb, the leaves are perfectly edible, and taste similar to kale or collards. Chop them up into a salad, boil them so they soften and make wraps, or you can stir-fry or steam them.