Three things have been found to be successful in overwintering dahlias in the ground above zone 7.

1. Luck (mild weather, hearty tubers, etc.)
   2. Mulch (protect ground from freezing down to the clump)
   3. Tarping (keep moisture from sitting in the soil, rotting tubers)

I've had clumps survive winters in 5/6 (never the ones I had hoped
would survive, though), during mild winters and no added mulch or tarping. I haven't bothered prepping for clumps overwintering in the ground, as they optimally need to be dug and divided yearly, anyhow. Mammoth multi-year clumps are scary, often needing pickaxes or chainsaws to divide, with a large loss of tubers. The blooms often start to under-perform after a few years, as well.

Each to their own. Try it, and let us know how it worked out for you.

Cheers!

Oh thanks These are mostly tubers that I bought this past summer, so aren't too old yet. Good idea about the tarp so water does't sit on the mulch pile. I've had my lilies bulbs rot in the ground in some places.

I never pulled out my gladiola bulbs last fall and they all came through fine this summer and bloomed well. For our zone, you are supposed to pull up those every fall.

I am also in zone 5 and sad to say I find Dahlia's will not survive our winters. I have tried pulling them and storing them and sorry to say have had no luck. If you find it works out, please share your success.

Most of the tubers I dug up last year did not make it either. I obviously am doing something wrong. I'm going to try really packing up mulch over a few of them and see if they will survive. And also dig some out and try to save them that way.

Sounds like a good plan. I hope one of them work, I personally have had no success and I followed directions on storing them to a T! UGH! They are so beautiful, especially the dinner plate sized blooms. One last suggestion, contact your local botanic garden and see what advice they may offer. Good luck :)

No way they will overwinter in zone 5. Too cold. Are you waiting until after a frost to dig them? And then don’t wash them clean but instead leave them someplace sheltered to dry (like a garage) and then store them in big plastic storage bins in mulch or wood chips in a place that is cool and dark.

Zone 5-I have had even the large dinnerplate dahlias live over in the ground although they get smaller as the years pass-It is in a protected walled garden with stone footpaths. digging is troublesome and iffy(spoilage) so I will try some in a little less protected area this fall (narrow bed south side between house and walkway) Heavy mulch of course. I also will dig some just in case...

What type of mulch do you use for the dahlias?