I've grown a load of perennials from seed, planted June time, in to modules, so they are now a couple of inches tall.
Should I plant them out in the autumn, or keep them in the greenhouse / cold frame until spring?
I pot most of mine on to bigger pots, then when they are bigger cut the tops of to bulk up the roots, keep them in a cold greenhouse then plant out early spring.
yes i'd pot them up into bigger pots now. If they're big and healthy in the autumn I might plant them out in a sheltered bed, otherwise overwinter them in the greenhouse for planting in the spring. Don't keep them in the greenhouse during the summer -too much stress, and you might forget to water them etc