Kohlrabi Bolting

[HotKat]

Hello,
A couple of months ago, I bought some small seedlings from one of the big box stores labeled "Japanese Stir Fry Broccoli". The label stated that they were very heat tolerant and could be grown all summer and used in stir frys. Well after transplanting and they had grown a little, I recognized they are actually kohlrabi. They are only about tennis ball sized, but have started to put out small flower buds. Do I need to harvest them now? Will they be too bitter, since they have flower buds. Can I just let them grow and harvest after the weather turns cold again? I've never grown this veg. I see where some people state they even plant them in July, but I'm in northeast Texas zone 8b and it's in the 80s here. It gets into the 100s during the summer. They are in an area that gets late afternoon shade, but sun the rest of the day. BTW, I have cabbage and brussels sprouts growing in the same area that are not bolting. Thanks for any info.

[applestar]

I’m not sure since I have trouble growing kohlrabi and have not had the opportunity to thoroughly investigate/experiment, but when they form flowerbuds, most of these types can be used like broccolini/rapini — so you could harvest those flowerbuds while their stems are tender and stir fry them.

I really do think kohlrabi is done as the bulbous vegetable once they start to bolt and is not possible to harvest them as such after the summer since they will have developed tough and fibrous base.

...wait — tennis ball sized? I think that’s big for kohlrabi — I Think unless you are growing the giants like Superschmeltz, kohlrabi is supposed to be about golfball to racketball size... like small/Asian turnips.

[pepperhead212]

Welcome to the forum!

It is probably the heat making them bolt. I usually plant the seeds indoors, and 3 weeks later transplant them. I usually start harvesting about 40 days later, so that seems like "old" kohlrabi, since I'm sure the seedlings you bought were older than 3 weeks. And the only problem I have had over the few weeks of harvest is that some varieties get tough - the only time I ever had them bolt was when the fall crop overwintered under a cover, and bolted as soon as spring came. But those won't oversummer there - if you see a hint of bolting, harvest. It seems they should be quite a bit larger, but I have had some varieties that didn't cut it, right next to others, in the same conditions.

If you are interested in a heat resistant green, try komatsuna (summer fest variety) and senposai (komatsuna x cabbage hybrid). A fellow I traded seeds with in TX in 8a planted a bunch of both, and could not believe how much he has gotten out of them, as they are the "cut and come again" varieties, that just keep coming back! They will eventually bolt, but mine usually last until late July, with senposai lasting into August several times, with a bunch of temps in the 90s finally triggering them. And, unlike lettuce, these do not become bitter when first bolting, so they don't need to be wasted.

[pepperhead212]

I forgot to mention that in my area kohlrabi is a spring and fall crop. I start it about 3-20 inside, and 3 weeks later they go into the ground, along with all the other brassicas. Then, by the last week of May, harvest starts. The good varieties - kolibri and grand duke are my favorites - get 4" easily, and don't get tough.

Just protect them from rabbits - they are their favorite snack.