There’s no denying the beauty of dahlias in a garden. Beyond their array of gorgeous hues, gardeners love them for another reason: “They are the lowest-maintenance, highest production plants you can grow, giving 30 buckets of cut flower per square meter within just a few weeks of planting,” says Sarah Raven, a gardening expert and author of A Year Full of Pots. “They also come in all shapes and sizes now, with ones that last well in a vase, ones that are stacked full of pollen and nectar — so good for butterflies and bees.” And the best part? They bloom later in the year “when there’s so much less around to love, look at and enjoy.”
But there’s one major mistake some people make when planting dahlias that can impact the flower’s growth. Planting them near “anything that draws in slugs and snails like bean plants,” Raven says. She also recommends keeping them away from delicate plants that grow slowly — think geraniums. “They look good at the same time as dahlias but will be choked by the stinking, vigorous growth of the dahlia family and don’t stand a chance,” she explains.
She also notes that if you’re planting “whopper” dahlias, which can grow quite large, avoid placing them next to smaller plants such as Cosmos “Sonata” or “Sensation” series or zinnias “as they will again be overcome.” However, if you’re not going with the whopper variety, Cosmos and zinnias can be a great to grow next to dahlias.
If you’re looking for more companion plants, Raven suggests “bold, strong growers like the grains, amaranths and sunflowers, which work aesthetically and feed the birds as their seed ripens. The birds then eat the caterpillars, aphids, slugs and snails and keep the place healthy and clean. It’s a win-win.”
Raven also says it’s a good idea to plant spore formers, such as gladioli, next to your dahlias. “Dahlias create undulating round shapes, and you want some vertical spikes to make a great design.”
And for next year, remember: “Plant the tubers inside, frost-free in mid-spring, don’t plant them just straight in the ground. Keep them in a cool, light, frost-free place until they’ve grown to a decent size (6-8 inches or so) before planting when the frosts are over out into the garden. Their juicy, soft shoots won’t get devoted by slugs and snails — a huge issue here with dahlias in a cold, wet spring.”
Monique Valeris is the home design director for Good Housekeeping, where she oversees the brand’s home decorating coverage across print and digital. Prior to joining GH in 2020, she was the digital editor at Elle Decor. In her current role, she explores everything from design trends and home tours to lifestyle product recommendations, including writing her monthly column, “What’s in My Cart.”
