In article , Nick Maclaren
writes

The truly perpetual spinaches are perennials like Good King Henry.

Winter and summer spinach are Chenopodiaceae in the same family as Good
King Henry, beetroot, quinoa, swiss chard, ruby chard etc. They are
perennials, best grown for cropping purposes as annuals or biennials.
--
Alan & Joan Gould - North Lincs.