Beetroot need to be grown quickly and don't like to be checked. Not sure if the rain was enough unless, Andre, your soil is heavy and wet. I sow in 4 rows, 3 inches apart, and space them 4 inches apart in the rows......as I do with carrots, spring onions, etc.......and keep them well watered. I have been picking now for some 6 weeks and they are juicy, tasty and delicious. Beetroot do grow unevenly so I just pick the biggest as they come. (the reason I sow as I do is because I use a home-made template on a handle to make my seed drills. It sounds too close spacing but in practice it works very well)