Dahlias bloom from July to frost, while peonies provide a display of late spring or early summer blooms. The attractive peony foliage provides a backdrop to the dahlia flowers. The plants have similar cultural and water requirements, so they do well in the same garden. Providing enough moisture is the main concern for healthy growth and blooming.
When first planted, both dahlias and peonies may require more frequent irrigation. Once the roots establish, they can draw more moisture from the surrounding soil.
Work plenty of compost or other organic matter into the soil before planting. These materials help the soil retain moisture and also prevent overly soggy conditions.
Don’t overcrowd the bed, as this leads to unhealthy competition for water and nutrients between the plants. Space the plants 2 to 3 feet apart in all directions.