PLANTING DAHLIAS

Dahlia tubers can be safely planted after the last frost, which is typically at the beginning of May in the Pacific Northwest.

Dahlias thrive in full sun but can tolerate some partial shade. Select a location with at least six hours of sunlight, sheltered from strong winds, and with excellent drainage.

Amend the soil by deep tilling and adding compost for improved fertility. Ensure the soil is loamy and well-draining, as dahlias do not thrive in waterlogged conditions. Adding peat moss can help if soil is heavy.

Dig a hole twice as deep and wide as the dahlia tuber. Add 1 tablespoon bone meal per tuber, to the soil. Place the tuber with the bud, or "eye" facing upward. See below for bud photo. If planting multiple tubers, space them about 2 feet apart to allow each plant enough room to grow.

Fill the hole with soil, covering the top of the tuber just enough. As new growth appears, gradually cover the stem with soil to strengthen it for supporting flowers. This is also the ideal time to install plant stakes, so to avoid piercing the tuber later. It is also helpful to write the dahlia variety on the stake.

Unless it's an exceptionally dry spring, avoid watering at the time of planting to prevent rot. Once new growth is visible, keep the soil consistently moist, especially during dry periods. Dahlias prefer well-drained soil, so avoid waterlogged conditions. Water at the base of the plant to minimize the risk of fungal diseases.

Snip off the main stalk of the plant when it is 12-18 inches tall to encourage stronger multi-branched stems and more blossoms. Remove lower foliage to promote good air circulation and to prevent powdery mildew. Remove spent flowers regularly to redirect nutrients and promote continuous blooming. Provide support by using stakes or cages to prevent branches from breaking.

Begin fertilizing plants after they have reached a foot tall and continue fertilizing every 3-4 weeks during the growing season. Use a fertilizer with higher levels of Phosphorus and Potassium, such as a 5-10-10 blend. Avoid over-fertilizing, as this can lead to excessive foliage growth at the expense of flowers.

It is recommended to dig dahlia tubers up to prevent them from potentially freezing during a cold snap, or from rotting by the wet winter weather. Before the first frost, dig up the tubers, thoroughly wash them off with water, allow them to dry, and store them in a cool, dry place for the winter. This prevents the tubers from freezing and ensures healthy plants the following season.