Turnips are only second to radishes for quick root crops. My carrots are still tiny, the beetroots are not far ahead, but the turnips sprouted luxuriant greens and started showing their purple shoulders after about 6 weeks. I needed to thin them, and we were having salmon for dinner, so I pulled three to go with.
The cultivar is ‘purple top white globe’, from Eden seeds. I put in ‘gold ball’ in the same sowing, but they haven’t done well, and have been overshadowed by their neighbours. They were delicious.