How to overwinter Dahlias

How to overwinter Dahlias

If frost is knocking on your door, you maybe wondering what to do with your dahlias.

Dahlias bloom beautifully in the fall – BUT they're not big fans of winter's cold. Yeah, dahlias may seem sturdy and charming, but when the frost arrives, they become a bit sensitive. We're talking about rot and freezing.

Now, you're probably wondering, "What's the deal? Do I dig 'em or not? How do I make sure my dahlias survive the winter?" Well, fret not; I'm here to spill the beans.

In this blog, I'm diving into the practical side of dealing with dahlias during winter – the decisions you need to make and the steps to take. 

Should you dig them up or let 'em chill in the ground? 

What's the best way to dig 'em up? 

And, of course, where do you stash them for the winter?

Let's ensure your dahlias survive the winter and come back stronger than ever when the sun decides to show its face again.


Should I dig the Dahlias up or leave them in the ground?

If the freeze in your area reaches a depth of 4-6 inches or more, do not leave your dahlias in the ground! That’s usually Zones 6 and lower. Also, if you have drainage issues and standing water you may want to dig up your dahlias to avoid rot.

In milder climates (Zone 7 and up), including the Pacific Northwest, you may try leaving the dahlias in the ground, but make sure you have good drainage in the planted area to avoid rotting from winter rains.


How to Protect Dahlias in the Ground:

Approximately two weeks after your first frost cut the plant's stalks down to ground level and cover your dahlia beds with straw, leaves, or any other mulch for insulation. You can add plastic on top. Containers should be moved to a location where they will not freeze, such as a garage or a greenhouse.

If you are growing in a hot climate (like Florida, So Cal, Hawaii, etc.), you should dig up your dahlias and store them in a cool place (40-50°F) for 90 days to give them some rest between growing seasons.


How to Dig up the Dahlias:

Start digging your dahlias 2 weeks after the first frost or approximately 120 days after planting. If you dig too early, you may risk that the tubers will still be in a "green stage" and will not have hardened off enough for winter storage. Their skins need to thicken like potatoes. 

How to: Use a pitchfork to carefully lift the tubers out of the ground without breaking their necks. If you don't plan on dividing the tubers until spring, you can store them unwashed.


How to store:


Dahlias are extremely cold-sensitive and need to be stored in a controlled environment. The ideal temperature should be between 40 and 50 degrees Fahrenheit. 


Proper humidity is also crucial. If it's too wet, they will rot, and if the tubers are stored too dry, they will shrivel up. The ideal humidity is 93-95%. To achieve this, you can store the tubers in plastic containers with vermiculite, peat moss, or sawdust/shavings. You can drill a few small holes into the bins to allow moisture to escape. If storing in crates or cardboard boxes which allow more air circulation, dampen the peat moss or sawdust lightly. 


Use the lasagna method to layer your tubers with the chosen medium and don't allow the tubers to touch. If they touch and one molds or rots, it will likely spread to the other tubers. Check on your tubers monthly! Remove any molding or rotting tubers to prevent the spread to others. If you notice shriveling, moisten down your medium with a little water to prevent further dehydration. If you notice moisture building up, open up the storage containers to vent.


Now put on your big girl overalls and get to it!

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