Get Growing: Fall rituals -- Finding next year’s dahlias

As I write this, the autumnal equinox is upon us – the day of the year when light and dark are served in equal measures. It’s the perfect reminder that fall is coming and with it my annual fall rituals. Rituals may be too heady a word. These rituals don’t involve dancing in the moonlight as much as scouring plant catalogs for seeds, spring bulbs and dahlias.

September is a perfect time to evaluate your garden’s dahlia game and scout for new team recruits. Late-August through early September is the time of dahlia festivals offered by dahlia societies and growers. If you missed these, don’t worry. This year was a slow one for dahlias, thanks to the endless and clammy spring we had, so there are still scads of blooms to enjoy at public gardens. 

Trial gardens are perfect places to find your new favorites. The Bellevue Botanic Garden and Volunteer Park have dahlia trial gardens planted by the Puget Sound Dahlia Association that will have blossoms to astound and delight you. The show should go through October – or when the membership digs the tubers up for storage. Another trial garden is at the Point Defiance Park in Tacoma. 

If there is a downside, it’s that some of these dahlias are so new they’re unavailable in the trade. I’m waiting for “Sandia Gold,” which I spied at the BBG in 2021. I think that’s what the washed-out marker on the stake read, anyway. It looked like a cabbage rose in butterscotch – minus the blackspot. Let me know if you see it. The good news is if you fall for some of these dahlias and they have been introduced for sale, you can likely find them at one of the PSDA’s sales around town next March. Botanical gardens’ regular displays, such as at the BBG and the Center for Urban Horticulture, usually have established varieties nicely tagged. 

There’s a lot to love about dahlias. The more you cut them, the more flowers they send out. They aren’t prone to many pests or diseases here, although it can be helpful to protect emerging tubers from slugs with cloches or slug bait and provide good air circulation to avoid powdery mildew. Dahlias are also promiscuous plants. Like a potato, one tuber can produce 20 or 30 more in a season. This makes them an economical crop if a variety is a reliable tuber-producer.

With the pots in my driveway, I should be able to start a small dahlia farm in the next two seasons. The larger varieties can grow six feet by three feet from a cold start in April. None of this slows my search efforts down for the next great dahlia. Instead, I enjoy giving the extras away to friends and neighbors. 

One of my favorite questions I get at the nursery is: “Are dahlias annual or perennial?” To which my answer is, “Yes.” Or if I’m feeling less sassy, I’ll say, “It depends.” 

Hailing from Mexico and Central America, dahlias crave hot weather and excellent drainage. Here in Seattle, this means a gritty hillside facing south or west is their happy place. Soggy soil will melt them like chocolate chips in a microwave.

They can also overwinter in pots – if they neither freeze nor get overly wet. This means, that besides having excellent drainage, the pot needs to be just-right sized – not so big comparative to the tuber(s) that it rots in the excess soil, and not so small that it freezes from the lack of soil insulation. That’s why people keen on the tubers’ survival, like the PSDA, dig up the tubers before frost, brush off the soil, label and store them in wood shavings in a cool dark place like a garage. 

I’ve learned a lot of this the hard way. There’s when to plant them, where and how. 

First, I planted tubers in March in the cold, wet ground, never to see them again. I learned that my back yard has one dahlia-friendly spot where they will return. Other spots, while sunny enough for raspberries, will still rot out dahlias. My sandy south-facing front yard is great for dahlias.

Another year, I planted them in pots indoors to keep all the way until April, but the pots were too big and many never sprouted, or were delayed a full season. I’m only now seeing the first blooms on some tubers planted in spring 2021. This year, I had much better results planting single tubers in 4- or 6-inch pots indoors and transplanted to 1-gallons outside when they got big enough – and the world got warm enough.   

Recently I became interested in the smaller single-flowered dahlias, which have a delicate charm compared to the billowy, bold double “dinnerplates” because they feed pollinators best. I’m in love with “Kelsey Annie Joy,” a sorbet confection in pink and yellow, but also the wildly contrasting “Pooh” – a traffic sign in red and yellow you can see from space. Then there’s the other myriad forms – little button “Valley Rust Bucket,” 2-inch spiral balls in pumpkin, or full-blown “Fairway Spur” – with mango flowers as big as a newborn’s head, it looks like a ruffled prom dress. “Crème de Cassis,” a 5-inch waterlily, brings all the drama with lavender petals framing a blackberry eye. “A la Mode” is a longtime favorite in my garden – striped in persimmon and cream, it adds excitement to any arrangement. 

I welcomed the puff-balled singles “Anemone”-style dahlias that look like the hottest new echinaceas but that come with a simpler owner’s manual. “Totally Tangerine” is orange with golden stamens, while “Mexico” is purple with a gold center expanding like its own galaxy.

Some of my choices are heirlooms, like “Kaiser Wilhelm,” a ball of yellow dipped in wine, and “G.F. Hemerik,” a beautiful single in the clearest orange. Both were from the historic conservationists at “Old House Garden,” an online catalog. 

You can wait for mail order in December through January or for nursery tuber sales in earliest spring through April. Online ordering gives you the pick of the world’s varieties. Several growers attend the Northwest Flower and Garden Show, too. For instant gratification, however, some growers, like Dahlia Barn in North Bend, offer dahlias for sale now you can pick up or have mailed to you in April. Just saying.