Mangel Beets

I did one year - planted them early like sugar beats and I was disappointed. My soil isn't the best - but I can grow good turnips. Well the Mangel didn't canopy enough and Ragweed got out in front of it. The tubers i had were more like golfballs to baseballs at best by falll - Weedy and not the 5-10 lb tubers I hoped they'd be. I went back to July planted turnips.
I got mine through Johnny's seed - they had them as a special a couple years back - I looked quick and I don't see them for sale currently.