When we moved here about 5 years ago I was faced with a large flowerbed in the middle of the drive way with only a few clumps of liriope. My husband and I spent time and money planting grasses. They died. The next year I spent more time and money. I planted "tough" perennials: coneflowers, blanket plants, bergenia, mondo grass..... They died.
Two years ago as I stood and looked at the barren bed, it occurred to my slow brain that there were not even weeds growing, except around the edges.
I have since put pounds and pounds of compost in the bed. I now have daylilies, coneflowers, daisies and, yes, weeds.
I do fertilize. We put some 10 10 10 on it every six weeks or so.
If you think you need it, go gently. Soil tests are a very good idea. But, IMO, good compost is like magic. I put a generous helping in every hole that I dig. And I scatter it around the daylily bed.