How To Easily Overwinter Dahlias Indoors [Canada]

Wondering how to overwinter your treasured dahlia flowers?  Today, we’re sharing two simple methods for overwintering your dahlia tubers indoors during Canada’s cold winter – both for those grown in pots and those grown in the ground.

With their stunning blooms bright colour, dahlias are a wonderful addition to any sun garden.  They are available in an assortment of heights from 18 inches to 4 feet tall. Their full floral displays come in any hue and combination of the rainbow – and that’s not all.  They also come in a variety of textures, too.  Some blossoms are well bordered, and others are ruffled or fringed.

At any rate, it’s difficult to say goodbye to them at the end of the summer.  But autumn doesn’t have to be the end of them, especially when a colour is difficult to find.  You can keep your dahlia bulbs over the winter.

Keep deadheading and caring for your dahlia as usual all the way through the summer to fall.  When the first frost hits, they’ll look terrible – so terrible you may even think they’re dead!  The leaves will be limp and transparent.

It’s true that this year’s foliage is gone, but the root is still good at this point.  If you would like to save for dahlia for next year, you have a couple of options.

How to Overwinter Dahlia Tubers

When it comes to overwintering dahlias, there are two options; trim them back and keep them in a pot or trim them back and keep them in a paper bag.

Potted Dahlias

Here’s how to overwinter dahlias that are grown in pots:

  1. Cut back the entire plant to 4 – 6 inches.
  2. Keep the dahlias in their pot over winter.
  3. Keep the pot in a cool, dry, dark place that doesn’t freeze.  Don’t water it, just let it stay dry.

Dahlias In The Ground

Here’s how to overwinter dahlias that are in the ground (or if you don’t have storage space for a container):

  1. Prepare a paper bag by adding some very light moist peat moss to a paper bag.
  2. Cut back the entire dahlia plant to 4 – 6 inches.
  3. Gently lift the root out of the soil.
  4. Dust off most of the soil and place it in the paper bag.
  5. Keep it in a cool, dry, dark place that will not freeze.  Some people have success with putting them in a spare refrigerator.

How To Care For Dahlias After Overwintering

On St. Patrick’s Day – why St. Patrick’s Day? Because that’s a day everybody remembers! – it’s time to get the dahlias growing again.  You don’t want to get it out of dormancy too early in the year because dahlias tend to stretch if the light is too low or if it gets too hot.  The warmth is great to get the roots growing but if it is too warm, they tend to get lanky.

For Dahlias Overwintered in Pots

If you’ve kept the dahlias in pots over winter, bring the container into the light and warmth & give it just a little water – about 2 cups. You should see some growth within about 2 weeks. Avoid giving it any more water unless it is very dry. Dahlia roots don’t initially need a lot of water because the nutrients come from the bulb.  Too much water will cause the roots to rot.

For Dahlias Overwintered in Peat Moss

If you’ve overwintered the dahlia in peat moss, plant it in a good quality potting soil with the bulbs placed about 1 inch below the soil surface.  Check the roots to see that they are firm and not squishy.  A squishy, soft, oozy root has rotted.  As above, give it about 2 cups of water, keep it warm and in the light and you should see growth in 2 or 3 weeks.  Avoid giving additional water unless the soil is very dry because dahlia roots get their nutrients initially from the bulb.  Too much water makes the roots mushy and they will rot.

Growing Your Dahlia After Overwintering

Dahlias like to burst from their bulbs in warm temperatures, but then they like to grow on in cooler temperatures of 16-20º C.

As the dahlia grows, pinch back the growth at the 3rd node.  Start counting at the very bottom of the stem where the first set of leaves emerge.  Call that first node ‘1’ and continue up to the 3rd set of leaves. Pinch or cut the main stem off at this level.  This will make the plant fuller and stockier.

Water when dry and fertilize weekly.

If you have any questions about caring for, overwintering, or getting bulbs started, please call us at 780-467-3091 or send us a quick email.

In the meantime, enjoy your dahlias!