Brian Killingsworth grew up in Charleston, SC, where his mother and father pruned Golden Celebration roses and potted Parrot Tulip bulbs. They were master gardeners in every sense of the term — backyard horticulturists stylized by the breadth of their planting knowhow. Killingsworth, however, adopted a narrower focus: “I major in dahlias,” he says.
A Vietnam veteran, he was introduced to the leafy, vibrant perennial in small-town Germany. The first dahlia he set eyes on was bright orange and oblong, though lately, the flower boasts more than 300 varieties. Some are subdued, like compact “pom-pom” types; other are known for their size and panache, including the Dinnerplate — which can grow up to a foot across — and the striped Awe Shucks.
Having commercially farmed the flower for 10 years in Ellijay, Georgia, and now a volunteer at Hendersonville’s Bullington Gardens, Killingsworth is a bonafide expert on overwintering — a common practice that can be compared to seed saving. Of course, there’s one small caveat: dahlias do not have seeds. Instead, their genetic material is stored in a central stem. This mother stalk produces small, potato-like tubers that can be preserved and then replanted come May.
As cooler weather settled into Southern Appalachia, Killingsworth gave Carolina Home + Garden the dirt on over-wintering — a lesson in both botany and patience.
How do you get the tubers from ground to storage?
After your first killing frost, dig that clump of tubers up. Right there on the spot, wash them real good. Clean all the dirt and worms off. Then place it on your work table and begin making diagonal cuts, being sure to get some of the mother stem with each tuber.
What is the best way to keep these starchy nodes warm through winter?
Buy some plastic tubs from the Dollar Store. Fill those tubs halfway with vermiculite; it does well as an insulator. Put the tubers in the box, cover them in the remaining material, and store them in a garage, shed, or even spare bedroom. They like to stay cold, between 40 and 50 degrees, but not freezing. They should sleep all winter long, though it would be wise to check on them once a month. There could’ve been some internal rot that’s worked its way out. Some might also be wrinkled like a raisin. That tells you they need a spritz of water.
Any warnings, tips, or screeds for new gardeners?
Most dahlia growers like to keep track of their varieties, so they’ll label each tuber with a permanent marker. A good rule of thumb is that if you can write on the tuber without ripping the skin, it’s ready to be stored. It’s not too wet or too dry. Also, it’s very important to know that vermiculite can produce a dust that’s not good for your lungs. If you want something more natural, use dog-bed filler. It smells real good, but because it’s so dry, you’ll have to keep an eye out on the moisture levels.
So why do all this work? What’s the advantage?
Down in Georgia, we’d do it to sell the tubers or to exchange them with other growers. But some people just find varieties that they like and they want to keep on growing them. I guess folks, like me, are just nutty.
Bullington Gardens is located at 95 Upper Red Oak Trail in Hendersonville, NC (bullingtongardens.org).