I planted dahlias for the first time this year. Do I really need to dig them up and store them for the winter?
In a word? Yes.
Dahlias aren't even close to being hardy in our northern gardens and not only will they succumb to our winters, it's unlikely they'll survive a hard frost. However, these tubers will live long lives as long as a little extra effort is thrown their way.
When your dahlias are actively growing in your garden, they're not all that much bother. Other than the occasional deadheading, they pretty much take care of themselves.
If you want real showpieces, you can practice the art of disbudding in which you remove most of the flower buds as soon as they appear so that the few remaining buds will develop into bigger, showier flowers than they otherwise would.
However, the practice is completely optional.
It's the arrival of autumn that ushers in the hard work.
When dahlias get hit by those first light frosts of the season, their leaves turn black. That's your cue to clip back the stems to about six inches above the soil level. Once you've done that, you can dig up the tubers and brush off any dirt that may be clinging to them. You'll also want to trim off any fibrous roots the tubers may have formed during the growing season before hanging them upside down for a few weeks to cure.
Moisture levels during storage are critical. If the tubers are too moist, they'll rot. If they aren't moist enough, they'll shrivel. For this reason, store your tubers in a well-ventilated container filled with a porous material such as peat moss, vermiculite or perlite. You'll need to check them on a regular basis throughout the winter to make sure there are no signs of mildew or fungus. If you see any, cut out the damaged plant material and return the healthy tubers to storage.
You may, however, discover you have the opposite problem, especially if you store your dahlias in a cool space other than your basement. If the tubers have dried out to the point of shrivelling, then you'll need to mist them before returning them to storage. Then you’ll need to check them in a few days to make sure they’ve plumped out again. If not, you'll need to remove any permanently shrivelled tubers.
If you have any questions or comments, please send them to me at vanessa@gardenmuse.ca.
Originally published in the Creston Valley Advance.
