Grow perennials from seed now
Sow a few hardy perennials to bloom this summer. For flowering in their first year, agastache, delphiniums, echinacea and Oenothera (gaura) will all do well.
Fill a pot with loam-based propagation compost and tamp down the compost to give a firm, level surface. Scatter the seed sparsely over the surface, cover with a thin layer of vermiculite or sieved compost and label the pot.
Press down the surface lightly and place the pot in a tray of water to soak up through the compost. The seeds will germinate on your greenhouse bench without heat but a propagator will speed up germination.