Daylilies
If you can’t grow anything else, try daylilies. Incredibly unfussy, these perennials bloom for just one day (as the name suggests) but in great profusion. You can snap off the flowers as they fade, if you’re a bit of a neatnik, or leave in place. In a few years, your daylily can be divided so you can plant elsewhere in your garden or share with friends. Daylilies require full sun.