A cool-season flower that can be set out in early spring, sweet alyssum fades in the summer heat, but its clusters of tiny white, pink, or purple blooms will likely cover your garden again in the fall when temperatures stabilize.

Fall flowers are a valuable source of nectar and pollen for butterflies and other beneficial insects at a time when food sources are scarce.

Squill are lesser-known spring bloomers, but these delicate white, blue or blue-and-white striped flowers are delightful. Plant them in large numbers; they also naturalize and spread readily. They’re extremely cold hardy and bloom in late winter to early spring.