I bought this book about growing veg on the balcony and the chapter on radish sounded promising. It says that after six weeks you can harvest. That seemed impossible to me but: challenge accepted!
I bought simple radish seeds in the supermarket and planted them into these little compostable pots for sowing. After a couple of days they sprouted already! Turbo radish I tell you!
So after a week I replanted the little plants into a bigger box. The box is placed on the windowsill where it is warm and sunny in the afternoon. I think in two weeks I will be able to place the box outside but I guess at the moment it is still too cold at night.