What do you feed?

Don't ever feed flowers and the veg don't get too much either. I've been mowing the lawns here now for 40 years putting the clippings on the compost heap or used for mulch and they keep on growing without being fed. The garden is fertile and when I plant potatoes and brassicas, I give them a good spadeful of compost from the heap. I assume onions, carrots parsnips etc. get the benefit of the compost the following year. I mainly feed the greenhouse plants.