Planting Guide - Dahlia Bulbs
Planting Dahlias in Your Garden
Dahlia Bulbs (tubers) are available in many eye-catching colors and exotic shapes to give you a spectacular show of color in borders, beds or even containers. Decorative, Karma, and Cactus Dahlias are all different types of dahlias based on their petal shapes, with Dinnerplate being the biggest. They have long been a favorite with gardeners as they are hardy and low maintenance. Dahlias will yield beautiful blooms from mid-summer through fall.
When & How to Grow Dahlia Bulbs
Unlike other bulbs such as Tulips, Dahlias like warm soils so plant your Dahlia bulbs during the warmer and longer days of spring. Dahlias are usually planted about the same time you would plant your vegetable patch. Dahlia bulbs can be planted as late as mid-June in most parts of the country.
Dahlia is an accommodating plant - it will grow almost anywhere! Dahlias will thrive in full sun but can tolerate some partial shade - the more sun, the bigger the flowers. Try to select a location that receives at least 6 hours of sun, sheltered from the wind and with good drainage.
Dig a hole twice as deep and wide as the Dahlia bulb. Put the tuber in the hole with the “eye” on the tuber facing up. The eye is the point on the shoulder, or crown, of the tuber from which the plant grows. If you are planting a number of dahlias in the same location, they should be separated by about 2 feet to give each plant room to grow. The shorter varieties can be planted closer together. Plan for the rows to be 3 to 5 feet apart depending on the size of the plant. Fill in with soil to just cover the top of the bulb. As you begin to see new growth appear, cover again with soil. Covering the stem gradually will allow the stem to strengthen so it can support the flowers.
Unless it is a very dry spring, it is not be necessary to water at the time of planting. The tubers will begin growing with the warmth and moisture in the soil. It is vital that they form a root system early in their planted life to assure a strong and healthy plant. Watering at the time of planting may encourage rot but as soon as your Dahlias are growing above the ground, water deeply to encourage strong roots.
A good rule of thumb is to water if the rainfall is less than one inch in seven days. Pots require more regular watering.
Young dahlia plants do not need a lot of water; in fact, excessive water can lead to rotting of the plant.
Good air circulation, especially near the ground is needed to prevent powdery mildew.
As the plants grow, remove any broken or damaged foliage. Once the plants are several feet high the lower leaves can be removed to increase air circulation. You may also need to stake at this point as some dahlia blooms can reach up to 10 inches across and become very heavy.
Your dahlias will continue to bloom prolifically right up until frost.
Preparing Dahlia Bulbs for Next Season
A heavy frost will kill the plant so you may want to dig the half a dozen or more tubers the plant has produced. Those tubers can then be stored and grown next spring! In USDA Zones 8 and warmer, dahlia tubers can be left in the ground and will bloom the following summer.