Dahlia Tuber Storage Tips

Here at Triple Wren, we get more questions about storing dahlia tubers than any other topic. This can be a hard part of dahlia growing for any gardener, so I wanted to tackle this topic today in hopes that it helps more of our flower friends to find success with their dahlia tuber storage.

In any tuber storage method, you have to accomplish 3 basic things:
1. Your tubers can’t freeze
2. You tubers can’t be wet
3. The air around your tubers has to be humid (80+% humidity)

Here at the farm, after labeling, digging, washing, and drying our tubers, they’re ready for us to store for the winter. (You can also divide your tubers before storing.)

Before storing, we completely dry our dahlia tubers. Warning: If you dig your tubers and either a) Pack them away before they’re fully dry or b) Let them sit out to dry for *too* long, they won’t store well.

We let our washed tubers sit on nursery shelves right in the field until they’re dry to the touch, and then immediately pack them away. On a clear, sunny day this might take 2 to 3 hours. On a sunny & windy day, tubers can easily dry faster. On drizzly, calm, gray days (common here in fall in the PNW), we move the shelves undercover, and drying can take over 24 hours.

The key here is, monitor your tubers as they dry. Don’t set them out to dry and go away for the weekend! Check them every few daylight hours until the tubers and any feeder roots are dried to the touch, and then pack promptly. 

Sidebar: If you’ve been watching our social media feed this fall, you might have noticed that we are beginning to dig our dahlia tubers before frost. We have so many tubers to dig that we can’t delay too long if we want to be sure we have them in before all-day freezing weather begins! Some gardeners believe it’s not safe to dig dahlias until after a hard frost, but as our friends in zones 9 and 10 (where it rarely frosts) can attest, and as we’ve learned after many years of extensive experiments, your tubers will keep just fine if dug before frost, as long as they are PROPERLY DRIED and then PROMPTLY STORED. So… to recap: if you’re wondering if you can dig before frost, you CAN, but be very, very careful how you handle your tubers after digging!

After we dry our tubers, we tuck them away into a place where we can manage the humidity well. (Humidity is the amount of water vapor in the air.) We pack our tubers with pine, fir, or spruce shavings in open bulb crates, and stack them in giant insulated storage containers (see video below). We aim for 80%-90% humidity in that storage container environment, and 40°F storage temperature. 

Another ideal situation for dahlia tuber storage is a good old fashioned root cellar, but most modern homes aren’t equipped with such awesome homesteading tools. Some gardeners store in an unheated basement, or in totes in their unheated crawl space or garage. (Again, see the video below for how we store our dahlia tubers on a large scale!).

Be sure to check your dahlia tubers frequently throughout the winter, to be sure they are the right temperature (too warm and they’ll sprout! too cold, and they’ll freeze!), are not drying out/desiccating/shriveling, and that they aren’t wet (condensation drips or precipitation can add unwanted moisture to tubers in storage!).