Originally published July 19, 2017
By Ciscoe Morris, former In the Garden writer
FEW PERENNIALS CAN match dahlias when it comes to producing nonstop flowers. Their showy blooms brighten any area of the garden, and if you get in half the trouble I do (How did I fail to notice those sheets drying on the clothesline when I turned on that sprinkler?), you’ll appreciate the long-lasting cut flowers for use in bouquets.
The blooms come in almost every color imaginable, with size varying from golf ball to dinner plate. Most local nurseries carry a great section of potted, ready-to-plant specimens.
Keep an eye out for the rarer varieties with red or purple leaves. They’re exceptionally attractive, with masses of colorful flowers that contrast beautifully with the wine-colored foliage. Plant your dahlia in as much sun as possible, in well-drained soil. To keep them blooming nonstop, keep the root zone well-mulched, and water regularly. Fertilize every six weeks by scratching a mixture of alfalfa meal and organic flower food into the soil around the root zone. Finally, remove spent flowers regularly.
Dahlias are generally pest-free. Not even deer eat them, but their one nemesis is earwigs. If the pests build up to sufficient numbers, they eat the dahlia petals right off during the night.
Fortunately, these critters are fairly easy to lure into a trap if you know the trick. Make the Ciscoe Earwig Trap by cutting off the top of an empty plastic water bottle where it begins to narrow at the neck. Then drop a teaspoon of the secret ingredient, canned fish-flavored cat food, into the bottle. Invert the bottleneck you cut off, and stick it inside the top of the bottle, pointing down like a funnel. Use Scotch tape to secure the bottleneck in the top. Attach strings to the sides of the bottle to allow it to be hung. Place a few traps in each plant that’s under attack.
Canned-fish cat food drives the earwigs crazy with desire. The little devils can’t resist the midnight snack and will enter the trap, only to discover they can’t find their way back out the next morning. Dump the earwigs into soapy water, or — because they eat harmful insects, rendering them somewhat beneficial — release them somewhere far from your dahlias.
Don’t leave the traps hanging for too long. They can get a bit pungent, and you’ll be amazed at how many new kitty friends you’ll have visiting your garden.
Most people dig and store their dahlia tubers in winter, but I leave mine in the garden. After the foliage dies back in the fall, cut the stems to the ground, and mulch over the roots with a thick cover of evergreen fern fronds. The fronds are great insulators, and they repel water, preventing the tubers from rotting in our cold, rainy winters. Although I’ve lost a few tubers in excessively cold winters, most survive to produce beautifully the following year.
If over time, however, your dahlia loses vigor and produces fewer flowers, it’s a sure sign the tuberous roots are overcrowded and need dividing. Dig up the rootstock in fall after the leaves and stems turn black. Tap off the soil, and dry the clumps in a frost-free area for at least three days before dividing.
Discard any rotten or shriveled tubers. Next, divide the rootstock, either into individual tubers or into chunks containing a few tubers. Make sure the tubers in the division are attached to a stem from the previous year, as those are the only ones that will produce growth the following spring. Wrap the divisions in several layers of newspaper, place them in open paper bags or cardboard boxes, and store them in your unheated garage.
Check the divisions occasionally. If any tubers are shriveling, spritz them with water from a spray bottle. If any long stems emerge from the stored tubers, snap them off right before replanting in early May. Then relax. You’ll have more than enough flowers for the spectacular bouquets to make up for all the trouble you’re undoubtedly going to get into next summer.