Answer: Here are some groundcover options that take full sun and cold winters:
Wooly yarrow (Achillea tomentosa) makes a flat mat of deep green hairy leaves with golden flowers on 6-10 inch stems in summer. Takes full sun and moderate water. Carpet bugle (Ajuga reptans) spreads quickly with runners. It has flowers on 4 inch spikes. Many varieties are available. However, it is susceptible to rot if drainage is poor. It takes full sun and regular water. Arenaria is often used as a lawn substitute. It has small white flowers in late spring and summer. It takes full sun and regular water. Phlox subulata (Moss Pink) reaches about 6 inches high. It blooms in late spring or early summer. There are many varieties available. Evergreen candytuft (Iberis sempervirens) is 8-12 inches high with shiny dark green leaves. There are many varieties with different bloom times. Some flowers are tall enough to use as cut flowers. You might also consider a low-growing, mat-forming juniper.
Here are a few groundcovers that take shade and should tolerate your cold winters: Vinca (periwinkle), partridgeberry (Mitchella repens), English ivy (Hedera helix), and bunchberry (Cornus canadensis).
Q&A Library Searching Tips