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Spokane, Washington  Est. May 19, 1883
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In the Garden: Ready to dig in to raising dahlias

Susan Mulvihill’s resolve to avoid growing dahlias began weakening when she first spotted the amazing blossoms at Tall Grass Farms in Medical Lake in September 2019.  (Susan Mulvihill/For The Spokesman-Review)
Susan Mulvihill’s resolve to avoid growing dahlias began weakening when she first spotted the amazing blossoms at Tall Grass Farms in Medical Lake in September 2019. (Susan Mulvihill/For The Spokesman-Review)
By Susan Mulvihill For The Spokesman-Review

When it comes to growing dahlias, I am a late bloomer. I’ve loved looking at them in other people’s gardens for years but never made the commitment – until now. My hesitance revolves around the fact that in the Inland Northwest, gardeners need to dig up the dahlia tubers each fall because they won’t survive our winters.

I hate to sound lazy, but, by that point each year, I’m just too tired to remember to do that. I’ve heard some folks grow them as annuals, leaving the dahlias to their fate during the winter, but I’m too thrifty to go that route.

Why am I going to grow dahlias this year? All of the glorious photos of them on social media made them too tempting. Last fall, I ordered a nice assortment of tubers from Tall Grass Farms in Medical Lake: AC Rosebud, Belred Desire, Cornel Bronze, Crazy 4 Jessie and Andrew Charles.

The owners, Nicki and Scott Farrell, grow thousands of gorgeous dahlias. Nicki recently shared her techniques to get me started on my adventure.

“Dahlias are pretty easy to grow,” she reassured me. “Many people start them early in their greenhouses, but we don’t. I find that I don’t gain anything by doing that because of the transplant shock.”

She plants her tubers directly into the ground in late April, which is before our typical last frost date of mid-May, explaining that the ground will protect them for the first few weeks.

“Many people wait until after Mother’s Day to get their tubers in the ground, but I always think they are waiting too long,” she said. “With our hot summers, the sooner you can get the plant through that first big growth spurt, the better. The foliage will shade the ground and keep the roots cool.”

She instructed me to plant the tubers 6 inches deep and add a slow-release fertilizer into each hole. It’s important to provide every plant with a strong stake and put it in place before filling in the hole so you don’t stab the tuber. Standard spacing for dahlias is 12 to 18 inches between plants.

“We generally get enough natural moisture in the spring so you don’t need to water as long as there is some moisture in your ground at planting time,” Nicki added. “I always hear that you shouldn’t water when you plant tubers, which is true for some areas, but I find our ground is usually bone dry. Once I plant them, I either hope for rain or water them right after.”

What about feeding the plants once they’re up and growing? “Midway through the season, you can add a bloom booster type of fertilizer to promote more flowers, but don’t fertilize late in the season as this can cause trouble for tuber storage,” she said.

Many years ago, I grew a few dahlias but forgot to dig up the tubers in the fall. This year, I have come up with a cunning plan to resolve that. I’ve dedicated one of my raised beds for growing dahlias. They should look stunning in the middle of the vegetable garden, and since I always tidy up the beds at the end of the season, I won’t forget to dig them up. Problem solved.

“The big thing I always tell people is don’t make dahlias more complicated than they need to be,” Nicki told me. “They really are easy to grow.”

Susan Mulvihill is author of “The Vegetable Garden Pest Handbook.” She can be reached at susan@susansinthegarden.com. Watch this week’s “Everyone Can Grow a Garden” video at youtube.com/susansinthegarden.

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