Beginner Gardening: A question about amending clay soil..., 1 by MsParTerre

MsParTerre wrote:
I have a poorly draining bed that is probably high in clay; heavy, compacted, no sign of worms. It's full of one to two-year-old perennials. So the soil has been amended a bit with each set of plantings, but it's clearly not great soil. Is it possible to add aeration and some kind of composting BETWEEN the young plants? There's still about 6" of space between each plant (a little less than in the photo here which was taken 3 weeks ago). Any suggestion would be great. I feel so bad to not have amended the soil well enough before buying and planting dozens of plants!