beetroot does not like being disturbed, but it is possible as i've tried it out this year. Sow in small seperate seed pots(i got mine from local Aldi store - 40 2inch pots in a tray for £2.99), thin out as they grow until you have a single plant per pot. This will ensure that the root is not disturbed when you plant out. i hardened mine off by putting them in a opened top cold frame/ box for a few days before planting. The good point is that you do not have to thin them out as they grow because you can plant them about 5 inches apart. the bad point, the beet root i sowed direct in the ground have grown quicker than the ones started in the green house!