There are dozens of ways to overwinter dahlia tubers, with many growers disagreeing about the 'best' way. it depends on your unique situation. i would suggest researching on the web, and try several ways this season. thats the best way to learn what works for you, and might save you from losing varieties during your learning curve. Here's some reading to get you started, but please know that long-time growers would disagee with some of what each source says.

The link at the bottom gives several methods that should be considered.

Swan Island says...
"Winter Storage--Use a storage medium such as slightly dampened Peat Moss, Sand, or Pet bedding material (sawdust/shavings). Tubers should be stored in crates or cardboard boxes. We recommend lining the containers with 10-12 sheets of newspaper. Start with your packing medium in the bottom and layer tubers and medium until the container is full. Never store in sealed plastic bags or plastic containers. Store in a cool, dry area (temp. of 40-50 degrees). Too warm they will wrinkle/shrivel and too cold they will freeze/rot. Please check your tubers once a month throughout the winter months."

Dahlia Barn says...
"There are many different ways to store your dahlias. We’ll give you a few different methods. Choose the method that you think would be right for you. If one method doesn’t work, try different ways of storing from year to year and stick with what works best for you. You can be as fussy or carefree as you need to be with your dahlias.
The most important tips are:
Make sure they never freeze wherever they are stored.
Make sure they are dry before they go into storage.
Some people will use a peat moss method below for colder climates. Other options are:
Store in clump form or divided loose in paper or plastic bags. No peat moss.
Cardboard boxes, wood boxes, plastic boxes or coolers lined with newspaper.
Keep the temperature at 40-50 degrees at all times during winter storage. The humidity should be kept medium-high to keep tubers from drying and shriveling. Check your tubers at least once a month during winter storage. If they do show signs of shriveling, give them a spray of water from an ordinary spray bottle.
Winter Dahlia Storage / Colder Climates

You can follow the directions for Easy Winter Dahlia Storage / Warmer Climates if you have an attached heated garage or cellar. You can store anywhere that the temperature will stay 40-50 degrees and never freezes. Outside sheds in colder climates will freeze and are not recommended as a place to store your dahlia tubers.
Start with a cardboard, wood or plastic box lined with newspaper.

Our eastern Washington Dahlia Barn.

Add a layer of peat moss for added protection from cold temperatures.
Add your dahlia tubers in clump form or divided.
Add another layer of peat moss.
Add another layer of dahlia tubers.
Repeat the process until your box is filled. You may need more than 1 box if you have a large amount of tubers."

Here is a link that might be useful: Tuber storage methods from www.dahlias.net

Has anyone tried using shredded newspaper instead of wood shavings? I have lots of shredded paper.

That would hold the moisture in, not wick it away. If they were well dried, there was no temp fluxuation and no pathogens on your tuber surfaces, I'm sure it would work fine.

But you can get a big bag of pine or cedar shavings at The big "WM" for $8 in the pet section labeled at bedding. Or a big hardware store should have vermiculite for sale... Just make sure it's not fine- the bigger chunks the better, or it will hold in the moisture too.

I just humbly suggest not storing everything the same way until you have good results for a couple seasons with one method.

Thanks, CC, for your response. Think I will try the shredded paper on one group of extra tubers of a common pink dahlia.

The method that has worked most reliably for me is to just dig up the whole dahlia tuber clump including the surrounding garden soil and pot it up in a large pot or 5 gallon bucket. i fill the cracks with more garden soil and then store the container in a location that stays just above freezing like an unheated basement or garage. It's ok if the soil has a bit of moisture but it shouldn't be totally water logged. I find that my tubers come out of storage nice and firm with no shriveling or rot using this method. It does make for some heavy lifting but it has been the most reliable method for me. You probably wouldn't want to do huge quantities this way. I've done about 120 clumps this year often storing 2 clumps per 5 gallon bucket. I divide in the spring.

I tried the plastic wrap method last year with mixed results. I had some rot and I stored a lot of tubers without eyes because the eyes are not very visible in the fall and you have to divide in the fall if you are using the plastic wrap method. It definitely cut down on storage space and weight though.

Last year I used dry compost but as our winter was so mild I did not lift the tubers until January and replanted them in March, the tubers were perfect but they'd only be in storage a few months. This year I have no dry compost and as it's so damp at the moment, no easy way to dry it out. I am planning to use shredded newspaper. It's clean, light and cheap. It absorbs water and I will leave the top of the box open, so if there is any moisture it can escape.

I tried shredded bills this year as a trial on extras, packed loosely in paper bags... had to go in and spritz lysol over a quarter of them, as the shredded paper held in too much moisture and some surface mold developed. Others packed in paper bags with no medium or course vermiculite had no surface mold.

The other trial this year was wrapping loose tubers lightly with two sheets of newspaper, and storing in an OPEN shopping bag. Working pretty good, as long as the bag can stay open.

My experience is that the tubers off-gas moisture for the first month of storage, then come to an equilibrium for the rest of storage (as long as room humidity levels stay even). I always dry the tubers for a good week before packing, whether or not I use water to wash them off.

An acquaintance of mine just stores her tubers in net bags with no wrapping at all. She stores them in the attic of her house, where there must be quite a variation in temperature but probably good ventilation. This has worked successfully for her for 40 years. The important element in all these methods seems to be, ensure the tubers are good and dry before they are stored.

Sounds like she has die-hard varieties that take a beating. Unless... Does she leave soil on the clumps?

You are right about the 'good and dry' comment, but there is a danger of over drying to the point that the tubers become rubbery or shriveled (especially if left on concrete to dry). Depending on the drying conditions, this can happen very fast.

The type of variety has a lot to do with how well it stores. Many beautiful show varieties need to be babied, or grown and stored solely in pots to overwinter successfully, while some garden varieties can be left on the greenhouse counter all winte and do just fine.

You let them dry a week?! Mine were dried about 2 days and they shriveled up like raisins. I see your note about concrete and that must be the issue since that's where they were.lol. I had a few on a wrought iron patio table (in the basement) and they fared better but still not great.

I'm sorry to hear it... frustrating when tubers shrivel like that.

Storage of dahlia tubers is a tough topic, as so much depends on the varieties being stored, growing conditions before being dug, if you divide them, how mature the tubers are, what the humidity and temp are in the storage area, how long they have to be stored, chosen packing material, and on and on. Since there are so many variables, you'll find that many of the grower's solution they swear by just doesn't work for you, for whatever reason.

The important thing is try lots of ways until you find a reliable method that works predictably year after year for you. There is no ONE way to be successful storing tubers.

I have to report that using shredded newspaper was not a success, it trapped too much moisture, and being open allowed mould to develop. This may not have been a fair test as the tubers were not properly dry. I took all the tubers out and brought them into a cool but very ventilated place. Cut off all the mouldy pieces and gave them a dusting with anti fungus powder. Dried compost next to a radiator in the house for a week. Then used the compost to repack the tubers. I will how they have done in 2 months March, as I am away until then so can only worry about them from a distance.

I am interested in the comment about the show varieties needing more nurturing I would agree. I have quite a few I grew from seed, they have lovely flowers but don't last as cut flowers anything like as long as the named hybrids. They make fantastic tubers which are easy to split so I have plenty of tubers if some fail. The named hybrids don't seem to make really big tubers and are often in very tight bundles so very hard to clean and dry. Plus being near the coast our winters are soggy and damp.