I am usually leery when I read claims about ‘giant’ vegetables. So when I first heard about a giant kohlrabi that could grow to 10 inches in diameter, I didn’t exactly rush to plant it. But last year when I saw that Johnny’s Selected Seeds had an F1 variety of Kohlrabi called Kossak listed, I became slightly less skeptical. I have found that Johnny’s is not prone to overly hyping its seed offerings. So I decided to give it a try last spring, and I was pleasantly surprised by how well it did.
Kossak growing
Most kohlrabi are best harvested when they are tennis ball or baseball sized. They usually start to get woody if they are much bigger than that. But Kossak kohlrabi can grow to 8 inches or more in diameter and still stay tender, though mine usually top out around 5 to 6 inches wide. That is still a big kohlrabi! It does take about 8 to 10 weeks after setting out transplants for it to size up. Of course, it can be eaten earlier, when the kohlrabi are smaller in size, but still bigger than most other varieties.
harvest of Kossak kohlrabi
For the biggest kohlrabi, the plants should be thinned to around 12 inches apart. Or if setting out transplants, plant them that far apart. I set mine about 8 inches apart. The seven kohlrabi in the above photo weighed in at 14 pounds after trimming off the leaves. The largest one weight a whopping 2 pounds and 10 ounces (1.2 kg)! And these large kohlrabi are still nice and tender, without being the least stringy or woody.
softball sized Kossak kohlrabi
The slugs have been eating on everything this year, and the kohlrabi is no exception. Despite considerable feasting on the skins and leaves of the kohlrabi, the damage is superficial and didn’t stop the kohlrabi from sizing up nicely. And the skin gets peeled away before using anyhow.
Kossak is great for making Asian Kohlrabi Slaw
Kossak has performed well for me the last two years. I have been planting it in spring, which is when kohlrabi usually does best for me here. I just now started more seeds to grow some for a fall harvest. We will see how it does. In the meantime, we have plenty of kohlrabi to enjoy from the spring planting!
sliced Kossak kohlrabi
I hope you have enjoyed this spotlight on a somewhat unusual variety of a vegetable that isn’t exactly well known. To find other great varieties, visit Suburban Tomato where Liz hosts the Saturday Spotlight series. I’ll be back soon with another variety.
To see my other Saturday Spotlights, visit the Variety Spotlights page.
Your kohlrabi are so big and beautiful and the Asian slaw looks luscious!
I’ve tried to grow kohlrabi before but either earwigs or rabbits got to them.
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Great post. I love kohlrabi but have never tried growing it. I’m amazed that it grows so quickly.
I was unfamiliar with kohlrabi but I’ve seen it popping up in different places, so thanks for spotlighting it.
Loved that you have information on these large kohlrabi. My Lancaster CoOp just delivered one of these gentle giants and I needed a recipe. The slaw looks appetizing and I have some black sesame seeds to finish the recipe. Thanks, Dr. M
Our other favorite thing to do with kohlrabi is roast them, either by themselves or mixed with carrots, potatoes or other veggies. I hope you enjoy those kohlrabi!
Hi Dave: Happy Holidays. Your post assured me to buy the seeds of this Kossak Kohlrabi. As you said, I don’t quite trust what the seed company’s description, but I do trust a gardener’s review as what you did. Did you sow directly to site or started indoors first? When did you transplant to site in Spring? Thanks for any advice.
I do start the Kossak indoors, and try and get the seedlings planted out in early April for the spring planting.
Thank you so much.
Very helpful! Just picked 8 of mine and are bigger than 8 inches, but still very good! Will pick the rest smaller