We live in zone 7b, it is a bit too early to plant anything outside, but usually around the end of March I can plant kohlrabi, peas, onions and some salad varieties outside.
I usually purchase kohlrabi plants from our local garden store, but this year I decided to try starting kohlrabi from seeds. A couple months ago someone mentioned on a Youtube channel that I watch that you can use empty toilet paper rolls to start seeds. The advantage of this method is that when it is time to plant you can plant the whole roll, the plants will continue to grow, and the cardboard will eventually become worm food.
In any case it sounded like a good way to repurpose the rolls, so why not.
While I was at it I decided to try peas as well, so I planted 6 rolls with peas and 6 rolls with kohlrabi. I also planted 3 of each in some biodegradable pots that I found at our garden center.