Only thing to add is that they do like plenty of water to bulk up.
Just to add , you can get purple and green and both yummy!
I have never eaten Khol rabi, what is the flavour?
The word kohlrabi is German for “cabbage turnip”
Raw - peel it and cut it into slices like you might an apple - it tastes like a cross between a potato and a cucumber - very refreshing and brilliant eaten as a snack.
Cooked - it has a unique taste, it tastes a bit like broccoli stems, but milder and slightly sweeter. It's delicious. Here is a recipe from Germany that tastes good - https://www.thespruce.com/kohlrabi-side-dish-recipe-1447381 - I add a little cream to the sauce - naughty but nice. There are loads of other recipes - just look on the internet. Enjoy!!