Dahlias’ days are over

It’s dark now. As I look out the window towards my garden, a reflection of the mess on my desk bounces back at me. I don’t really need to see the garden to know what’s out there but over the last few months I have gotten used to scanning that view for inspiration. And if that failed, I’d go outside. But along with being dark, it’s cold too. The end of Daylight Saving Time and the first frosts (in pretty perfect sync this year) make the transition from growing season to dormancy feel abrupt. But looking back on a fall still so full of color it takes make breath away, I can recall that the darker season has been sneaking up slowly in its usual series of fits and starts.
I was ready when frost finally settled in patches on my garden and hope you were too. But now my back deck, so recently the prettiest place, looks like it was abandoned in haste. Pulled weeds and dead leaves are littered about; pots of blackened surplus coleus—they were the first to go—make for macabre decoration. It’s just as well I can’t see all that out my windows right now or I might feel like a slacker.
I’d forget to pat myself on the back for hauling angel’s trumpet, lemon verbena, a fig, lantana, begonias, and some fuchsias down cellar last week. I intentionally left them outside just long enough for them to set their dormancy clocks to chilly short days in preparation for their exile into darkness. For the bees’ sake and hummingbirds’ (not that I’ve seen any for a while) I also resisted digging up stock plants of Cuphea ‘David Verity’ and red velvet sage (Salvia confertiflora) until hours before the temperature fell into their danger zone. Those plants, still wilted from transplant shock and added to the menagerie wintering on my south-facing entry porch (the plantry), might not make it but it was worth a shot.
My dahlias are next. Some gardeners who are in more of a rush than me to put their garden to bed, cut down and dig their dahlias before they’re hit by frost. For any of the robust varieties with thick tubers, that’s perfectly fine—although bumblebees will miss the last flowers. I am a procrastinator. I like to wait until stems and flowers turn to sludge and then procrastinate some more to make extra sure that their tubers get the signal to fatten full of the carbohydrates they’ll need to shoot out 4’ stems and flowers again next summer. A week or two past frost should do the trick.
After digging, drying them for a few hours to a couple of days in the sun, and shaking off most of the soil, I wrap the tubers loosely in newspaper and stuff them in a plastic storage bin to wait out winter in my basement. But that’s by no means the only way to store them. There are almost as many options for dahlias as there are gardeners. Some pack their tubers in crates of sawdust, peat moss, or potting soil. I know a few who stick them in paper bags. Others swear by plastic. It all depends on the temperature and humidity level of your cellar, garage, or closet. My cellar happens to be on the warmish, dampish side and so far (knock wood), I haven’t lost any tubers to either rot or desiccation. I have also never found it necessary to dust them with fungicide, which some old-school dahlia enthusiasts insist upon.
Once the dahlias are out, I can procrastinate again. I’m all for leaving seedheads for the birds and pretty stems standing for insect habitat and winter interest, and I’ll get around to cutting everything else back later. I can’t see any of it out my windows anymore anyway.

Kristin Green is the interpretive horticulturist at Blithewold Mansion, Gardens & Arboretum in Bristol, where she’s worked since 2003. Follow her garden blog at http://blog.blithewold.org.

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