Arrow-right Camera
The Spokesman-Review Newspaper
Spokane, Washington  Est. May 19, 1883

For memorable dahlias, start around Memorial Day

Spokane Valley gardeners Kay and Dan Loibl, shown standing in their garden last summer, are smitten with dahlias. (Susan Mulvihill)

Dahlias are lush plants with stunningly beautiful flowers. Ranging in height from a few inches to several feet tall, they are grown from bulbs called tubers.

Master Gardener Kay Loibl is hooked on dahlias. She grows more than 100 of them every year.

“Dahlias are so magnificent,” Loibl says. “It does take a bit of work to get them in the ground, but they’re worth it because there are so many different colors, shapes and sizes.”

She and husband Dan became dahlia lovers 10 years ago when they went to a dahlia festival at Swan Island Dahlias in Portland.

“That’s how we became addicted,” she explains, “because they had every dahlia you could imagine.”

The Loibls plant dahlia tubers on Memorial Day weekend or in early June.

“They don’t like to be cold so it’s best to wait until the soil is warm enough,” Kay Loibl says.

To prepare the soil in their flower beds, they till in compost, leaves and other mulching materials. They avoid adding anything that is high in nitrogen like grass clippings and manures.

Kay recommends putting sturdy stakes in place before planting the tubers.

“If you’re going to grow 4-foot-tall varieties, you need really strong stakes,” she says. “We use 4-foot lengths of rebar that Dan has painted green. You can also use tomato cages or bamboo stakes.”

Each planting hole should be four to six inches deep.

The Loibls add a handful of bone meal and work it into the soil before adding the tuber to the hole. They place the head of the tuber where there is a sprout, or “eye,” next to the stake.

Tubers should be planted 18 to 24 inches apart.

“If the plants are too crowded,” Loibl explains, “they will be stressed. It will be harder to get water to them, and they will become more susceptible to mites.”

One of the most important rules is that tubers shouldn’t be watered at planting time. Once the plants are up and established, they need deep watering two to three times weekly.

About 30 days after planting, the Loibls apply a fertilizer high in phosphorus and potassium, like 5-10-10 or 10-20-20. They also deadhead the flowers regularly to keep them blooming.

The tricky thing about growing dahlias in our region is that you have to dig up the tubers each fall and store them over the winter. But Loibl says it’s not all that difficult.

“Let the plants go through a hard frost, then leave them in the garden for a week after that,” she advises.

“Dig up the clumps of tubers and wash them thoroughly. Once they’re dry, you can divide them, if necessary. We use a box-cutting knife to divide them and save the three best tubers from each plant.”

The Loibls store the tubers in styrofoam coolers lined with sheets of newspaper. Peat moss, sand or sawdust can be added around the tubers.

“Never store them in sealed plastic bags or plastic containers because they will rot,” Loibl advises. The ideal storage temperature is between 40 and 50 degrees.

So why not take the plunge into the glorious world of dahlias this year? See the accompanying information box for cultural information and upcoming sales.

Susan Mulvihill can be reached via e-mail at inthegarden@live.com.