If you have perpetual spinach beet, then you will find that if cut back,leaving 5-10cm above the root top, they will send up new leaf shoots, but probably also a new seed head! I top mine with a swap hook, similarly chard and sometimes beetroot if requiring baby leaf from overwintered stunted beet (from "too-late sowings")
If its New Zealand 'spinach', then beyond my experience.
The same technique also gives results with annual spinach, but the more delicate trimming with scissors or sheep shears leaves them still planted!