Dahlias can be a favorite flower in any landscape, they are easy to grow, available in a large variety of colors and types, and continuously bloom from midsummer until fall frost. March is the time to remove them from storage and start sprouting the tubers if you wish to have earlier blooms.
To determine if each tuber has an eye (new growth bud), I pre-start them. This eliminates the process of time consuming planting only to find they did not show any growth because some did not have an eye.
The tubers need to be separated from the stem by cutting off separately to obtain several plants from one clump. The eye or bud is located at the end of the tuber next to the large main stem. There is a slight swelling or roughness where the buds will begin to swell and grow. Remove any damaged or small tubers.
Place the cut pieces in a box or pan with damp peat moss and cover slightly. Keep them medium moist and in a warm spot until growth begins. If you are apprehensive about cutting the potato like growths from the stem because you are not sure where the eyes are, you can place the whole clump in the medium and cut apart when new growth starts. Do not let the new sprouts grow more than one inch or they could be damaged when planting. Plant in the garden or pot when danger of frost is past.
The planting or potting soil should be light and well drained. If soil is heavy, add peat moss or compost and work to a depth of about 12 inches. The dahlia tuber is planted about 4 inches deep. Place the eye or new sprout up. I use a method used by some potato growers, planting and covering with a couple inches of soil adding as growth extends until the hole is filled.
Dahlias do not grow well in rich soil especially high in nitrogen. A slow-release fertilizer added in the planting hole such as 5-10-10 or similar is desired. Read the formula on the container of any fertilizer you buy. If soil is damp at planting time you do not need to water as dahlia roots are susceptible to root rot before established. When growth is about 10 inches high, water weekly. Watering thoroughly will promote more flowers.
Pinching the tip of the plant when it is 10 or 12 inches high promotes bushier growth and more stems for more bloom. Pinching should be done above a three leaf stem. Dahlia blooms love cutting and you can take long stems including forming buds along the stalk. Cut off or deadhead all spent flowers for abundant color until fall.
The only problem I have with dahlias is their propensity to breaking and toppling over. They need to be staked and not lightly. They get very heavy and require several stakes per plant. I tie the stalks separately with nylon hose. It stretches easily and will not damage the brittle stem.
This year, as I am weary of staking with the exception of a few, I will plant dwarf or border dahlias. There is a wide selection of colors and varieties in the taller dahlias but I have not seen the dwarf type for sale at markets. There is a good selection of these in the myriad of catalogs I received in the mail.
I think everyone has the problem of not enough sunny areas in their yard as I do. Dahlias can tolerate part shade or just four hours of sunshine. Of course, all plants do well and bloom more prolifically in full sun if it is available.
Betty Winscher is a Master Gardener and can be reached at (320) 584-8055 or via e-mail at firstname.lastname@example.org.