I’ve been asked what kind of perennial flowering plants would grow well on a slope, and at the base of the slope in an area shaded by trees.
Groundcovers work well on slopes. If the slope is in a full sun area you could try planting St. John’s Wort (Hypericum), Vinca minor, Ajuga, Verbena, and Wintercreeper. In shady areas you might try Vinca, Ajuga, Wintercreeper, Cornus canadensis (Bunch Berry), Bergenia, and Lamium maculatum.

Prepare the planting area well by removing weeds and amending the soil with organic matter. The organic matter will help hold soil moisture, and act as a natural fertilizer for the plants too. You can also add organic mulch around the plants to keep the weeds down until the plants start to grow and spread.