Many of the listed varieties are not true beets but are grown on a similar regime for the use of the leaves as an alternative to Spinach. The flavours are somewhat milder than Spinach but also give a crop in late summer and into winter when Spinach would not thrive.
Sow the seeds 2cm deep, where they are to remain, in rows about 45cm apart in March or April for harvest from June onwards. Thin to 10cm between plants.