Save your favorite dahlia tubers from the best plants in your garden so you can grow them again next summer.
Did your dahlias go from this to this? Well, then they have gone dormant and it is time to dig them up and store them for winter!
Why Should I Store My Dahlias Over Winter?
Not everyone needs to overwinter their dahlias indoors. Dahlias are annual plants in zones 1-6, maybe even some in zone 7.
They will not return to regrow after winter, so you will have to replant tubers fresh the following year.
But if you live in zone 8 or warmer, you can leave your tubers in the ground all year. Dahlias are perennial for you.
Gardeners in zone 7 can try mulching dahlia tubers with a heavy mulch layer and leave them in the ground. Zone 6 is pushing the limits of leaving dahlias in the ground, but if your winters are typically dry and relatively mild, try applying both mulch and a frost blanket to protect tubers from freezing.
I’m in zone 6 and I have trust issues with the weather, so I will be digging up my dahlias every year! Our winter weather is so unpredictable, and we have gone below 0°F often enough, that I think it’s worth digging up my favorite dahlias and saving them indoors year after year.
When to Start Overwintering Dahlia Tubers
Let’s start the overwintering process by digging up the dormant tubers. Ideally, you will want to wait until the tops have died in a light frost, but you can also begin digging up tubers before the tops have been killed.
If you have had a frost, dig up your dahlias right away. You don’t want the tubers to freeze or to begin rotting at the stem.
Also, if you have rain forecasted soon, try to dig the tubers up before then to make it easier to get them out of the ground, particularly if you have clay soil.
I try to wait as long as possible to dig up my tubers so that they will have to be in storage for the least amount of time.
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Dig Up Dahlia Tubers
Now that it’s time to dig up the dormant tubers, grab a shovel and a wagon to transport those heavy clumps. Be as gentle as possible during this whole process. You probably want to save as many tubers as you can, and broken dahlia necks and split tubers will not grow.
First, I like to brush the soil away from the stem and try to locate the tuber clump growing below. Just to get an idea of how big the clump is and where it will be safe to dig.
Insert the shovel about 8 inches away from the stem to avoid cutting into tubers. Loosen the soil with your shovel until the dahlia plant pops out or falls over. This is the best part. I get such a kick out of digging tubers like dahlias and potatoes out of the ground!
Then pull the plant out. Make sure your tuber clump is labeled. (I just stick the plant tag into the clump and that works short-term.)
Wash the Dahlia Tubers
Some people leave the dirt on their tubers for storage, but I like to wash and inspect the clumps before I put them away.
Often I’ll find one that rotted out or was nibbled on that I don’t want to save.
I use the jet function on my favorite hose to spray off dirt, trying to get in the center of the clump where dirt really gets stuck.
Afterward, I cut the stems off to get them to start drying out.
Divide the Clumps… or Don’t
Once the dahlia clumps are clean, I leave them in the garage for two days to dry out a bit. I don’t put them directly on the floor because that could damage them and dry them out. Instead I leave them in my garden wagon and sometimes I’ll cover them if it’s a particularly cold week.
I like dividing my dahlia tubers before I get them stored just because I can store more tubers in each box. Clumps are big and awkward, and I find that the necks of the tubers break too easily in a clump.
I explain how to divide dahlia tubers in my previous post.
This year, however, I’m experimenting with leaving a few clumps intact and storing them in a box full of vermiculite. More on that later.
Make sure to label the tubers well. They all look the same without their flowers and it’s easy to get the varieties mixed up!
I write the dahlia name directly on each tuber with a permanent marker. This does not harm the tuber and it guarantees that the label won’t fall off and leave me guessing the identity of the plant.
Wrap and Box the Dahlia Tubers
After dividing the dahlia clumps, I wrap each individual tuber in plastic. Usually, I’ll use one sheet of plastic wrap, roll a tuber in it, then add more tubers as I roll up the sheet, so that they are not directly touching one another. This method also helps keep tubers categorized and identified.
Once the tubers are wrapped, I put them in a plastic storage box with a lid and keep them in my garage under a blanket. I have a thermometer in the garage that I monitor as I go in and out. If temperatures get below 32°F, I bring the dahlia tubers inside until temps come back up.
As I mentioned earlier, I’m trying to leave a few dahlia clumps intact and storing them in vermiculite.
Here they are in their plastic storage box and covered with vermiculite. I sprayed the vermiculite with a tiny bit of water so the box isn’t bone dry. Dahlia tubers do need a tiny bit of moisture so they don’t shrivel up and dry out. Remember, the tubers are alive and still need oxygen and moisture to stay healthy.
This box will be stored in the same location as the box of plastic wrapped dahlia tubers.
Keep Tubers in a Cool, Dark Location
Again, I keep my dahlia tubers in the garage under a blanket and bring them in if temperatures in the garage go below freezing.
The blanket helps to keep the dahlias in the dark and also protects them from the extreme cold. Even though they are in the garage, it does get very cold from the garage being unheated and from us opening the main doors to get in and out.
Once it gets closer to spring, I do a check to make sure the tubers are healthy and not moldy or shriveled up.
Wake Up Dahlia Tubers in the Spring
I try to wait until March or April to wake up my tubers, but I do get overexcited sometimes.
Potting up dahlia tubers ahead of time helps them get started growing faster, which also means getting flowers faster. I also like to propagate dahlias at this time so that I can have more plants in the summer.
When you take the tubers out of storage, check them over to be sure the necks are intact (not broken or bent) and the tubers feel firm. Discard any that are squishy or rotting. If your tuber has a bit of mold on it, try wiping off the mold with a wet paper towel and a little bit of hydrogen peroxide.
As long as the tuber is firm and not rotten, it should be ok.
To wake up the dormant tubers, just place them in damp soil and put them under a grow light. The light, warmth, and water will start to bring them out of dormancy and they should start sprouting at the eyes.
Some dahlias take a long time to begin growing again, so just be patient and keep them warm. Even the deadest looking tubers will sprout once they’re good and ready.
Then they will be ready to go into your cut flower garden.
Check out this post for my top 10 easy-to-grow flowers for your cut flower garden, including dahlias!
Ready to Start Digging?
I hope that this explanation of my dahlia overwintering process helps you save your dahlia tubers for next year.
I love that dahlias are so easy to grow and multiply. You can start with just a single tuber and end up with so many plants by the end of the growing season.
Do you overwinter your dahlias? Share any tips or tricks you have in the comments below.