If your perennial flower garden gets a little drab and boring come late summer and fall, think about planting dahlias. Gardeners are always trying to find colorful flowers to keep the show going into autumn, and dahlias are the perfect star to fit the bill. Dahlias just need a little more thought and attention compared to other perennial flowers.
Dahlias offer a wide range of flower types. There are flowers shaped like pom-poms, anemones, cactus, orchids, and water lilies. The flowers come with single or double petals and in almost any color of the rainbow from white to purple. Some varieties produce flowers the size of a dinner plate, while others have small flowers on dwarf plants.
Whatever dahlia variety you choose, they all grow from tubers planted in spring. Dahlias are winter hardy in USDA Zone 7 and warmer zones. In colder areas, the tubers need to be dug and stored in winter after a frost. Gardeners in warmer-winter climates can treat dahlias like perennials. Due to threats from disease and insects, however, some gardeners in warm-winter climates still prefer to dig and store their dahlias to protect them.
Plant dahlias on well-drained soil amended with compost. Dahlias grow best in full sun, but can take some afternoon shade in the South. Plant tubers about 4 to 6 inches deep in the soil. Unless your soil is extremely dry, don’t water until you start seeing signs of plant growth. Consider planting in groups and remember the ultimate height of your plants. Tall varieties look good tucked in the back of a perennial garden, while medium- to dwarf-sized plants look best right up front. For tall varieties, you may have to use plant stands or stakes to keep the plants upright. To promote bushier growth, when the plants are about 18 inches tall, pinch out the tip of the central shoot; this causes the plant to send out side branches, which will lead to more flowers.