I have been growing perpetual spinach for decades in the same spot year on year. A quick rake over, so no dig, no kind of fertiliser, so assume they are not fussy. Just sow the seeds lightly in rows and water in well.
I sow it in the ground in March and it starts producing well from mid May and continues till February.
I also sow more in August that starts producing late Autumn and continues till May.
Just picked a load this week.
Have had plants that continue well past May and just leave and pick them until the stems begin to get fat and on the verge of going to seed.
Of course every other year it is worth leaving one plant say in a corner to go to seed and use the seeds for the next few years.
Found the best thing to stop them going to seed is very regular picking and pinching out the tops, so it continues to produce and not allowed to go to seed. They do need regular hoeing and do seem to need lots of water, as the soil dries out very much near them.
Pick more than you need and just freeze spinach straight from the garden in tight balls.
I have though found that when thinning them out after the sowing that its hit and miss on the transplants, especially during the summer sowing. Think they hate the heat at that time when moving.
