Are you thinking about overwintering your dahlia tubers through the cold winter? I’ll share some different methods and simple tips on how to safely dig up and store your dahlia tubers during the winter season.
You have 2 choices when it comes to your garden dahlias during the cold, winter months.
- Leave your dahlia tubers in the ground through the winter.
- Dig your dahlia clumps up and store them in a safe and dry location until there is no danger of frost next season.
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I’m a self-taught hobby gardener, not a Master Gardener. Everything I share with you on my blog is my personal opinion and things that have worked for me personally.
How to Know Whether to Should Dig Up Your Dahlia Tubers to Overwinter
Where you live and the climate is basically how you’ll make the decision to leave your dahlia tubers in the ground or overwinter dahlias in a safe environment until the chance of freezing has passed.
Dahlias in Mild Winters
Because I live in a more mild climate (zone 8B), I’ve been very fortunate when leaving my dahlia tubers in the ground year-round. I’ve only dug up and stored my dahlia tubers once in the 9 years I’ve grown dahlias in my cut-flower garden.
If you do end up leaving dahlia tubers in the ground, it’s a good idea to protect them from freezing temperatures during the coldest months of the year. You can do this by adding a 3-inch layer of organic leaf mulch around each plant.
When we’ve had a wetter-than-usual winter and I’ve left the tubers in the ground, I’ve lost about 15% to rot, but I personally have had more rot damage the year I stored the tubers out of the ground.
Dahlias in Colder Climates
In most areas, winters are too cold to leave dahlia tubers in the ground. For those zones that have colder climates, dahlia plants should be cut back at the end of the growing season, and after the plant’s top growth dies back, or is blackened by the first frost.
With clean, sharp pruners or loppers, cut all but 4 inches of the top growth.
The longer the tubers are kept in the ground, the more mature they will be. This will give them a better chance of surviving in storage. But you do want to dig them up before the first hard freeze of the season.
You can find your average first and last frost dates here.
Splitting Dahlia Tubers in the Spring
You have the choice to divide your dahlia clumps when:
- digging up tubers to store them over the winter months
- it’s time to plant the tubers back in the ground in the spring
- you’ve left your tubers in the ground through the winter and need to dig them up around the last first date in spring.
I will dig up my dahlia tubers in April to split and inspect them, toss any rotted or diseased tubers, and remove the mother root or tuber.
After splitting them, I plant them back in their holes and wait for them to bloom in the summer.
Label Your Dahlia Tubers
It’s important to label your dahlias before their blooms die off so you’ll be able to keep track of each tuber once they are removed from the ground.
If you do not take your dahlia tubers out of the ground, you will still need to label them to be able to find the plants next year so you can dig them up to divide.
How to Dig Up Your Dahlia Tubers
No matter what option you decide on, you’ll need to go through these steps to start the process of digging dahlia tubers out of the ground.
Steps to Digging Dahlia Tuber Clumps Out of the Ground
1. Use either a shovel or garden fork, to dig around the dahlia clumps. Be careful not to accidentally sever the dahlia roots. I tend to use a pitchfork because the tubers are so sensitive.
2. Gently shake excess dirt off the tubers, and set them aside.
3. Repeat until you’ve dug up all of your tubers.
Options for Storing Dahlia Tubers
I’m sharing a few options for overwintering your dahlia tubers to eliminate any risk of frost.
Here are the best methods I have found.
This is the option I have used in the past to store dahlias.
Rinse the tuber clumps to remove all the excess soil and then wash them by dipping them in a 5% bleach-95% water solution.
After you’ve rinsed the tubers off, examine each clump to make sure that there is no damage or rot.
If the tubers have several growth eyes, you can divide them at this step in the process as well. Use a sharp knife or pruners to divide dahlia tubers, making sure each piece has at least one eye.
The eyes of dahlia tubers are the set of cells that produce the next season’s plants and blooms.
I personally have much better luck finding the eyes in the spring. So if you can’t find them in the fall, wait to divide your tubers when they may become more visible in the early spring.
To prevent rotting, make sure the dahlia tubers are completely dry before you store them for winter.
Some gardeners suggest setting them out to dry for several weeks before putting them away for the winter. Others recommend only a couple of days.
I’ve been lucky because we have a wood-burning stove in our outbuilding, so our tubers dry pretty quickly.
When they’re dry, place tubers in a dark and cool place for storage, where there is no risk of freezing temperatures. This would be preferably between 40-50º F. and could be in an unheated basement, closet, utility room, or attic.
Store dahlia tubers in slightly dampened peat moss, sawdust, wood shavings, or coarse vermiculite, and then place them in a cardboard box or paper bag lined with newspaper.
Tubers must have good air circulation, so make sure that they aren’t touching, and that they have enough room for proper airflow.
I check my tubers for rot once a month throughout the winter season.
I learned this option from Erin at Floret Flowers who is basically my gardening hero. Her flower farm is located in the same state, Washington, and is a few hours away from my garden.
After Erin digs her dahlia clumps up, she shakes off the excess dirt, puts the clumps into deep bulb crates, and stacks them in a 40-50º room in her basement for winter storage. THAT’S IT! She warns that most pros may question her tactics, but I have to tell you, I love this idea.
Erin says that the soil seems to keep the dahlias tubers hydrated enough to avoid shriveling. Then in mid-late March, she pulls out all the crates, rinses off the clumps, and starts dividing the overwintering dahlias.
This is the Saran Wrap method.
Rinse the tuber clumps to remove all the excess soil, and then wash them by dipping them in a 5% bleach-95% water solution. After you’ve rinsed the tubers off, examine each clump to make sure that there is no damage or rot.
Lay the dahlia tubers out to dry in a cool garage or basement for a day or two. Once the clumps are dry, carefully divide them and then separately wrap each individual tuber in a piece of Saran Wrap.
Read more about dividing in my blog post All You’ve Ever Wanted to Know About Dahlias.
Place the wrapped tubers into plastic bulb crates, and store them in a 40-50ºF space throughout the winter.
I have mixed feelings about this method of storing dahlia tubers.
- PRO: The plastic wrap keeps the tubers separate from one another so if one was to rot, the others would be safe.
- CON: Wrapping individual tubers in plastic wrap can be very time-consuming.
I hope this has given you some ideas when planning to store your dahlia tubers for the winter.
For more on dividing dahlia tubers or other information about growing dahlia flowers, you can read my blog post on All You’ve Ever Wanted to Know About Dahlias.
I’d love to hear from you, leave me a comment. Thank you for being here.
Until next time.
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Make sure you visit my friend Stacy at Bricks ‘n Blooms to find out more about gardening for summer highs and lows. Stacy is a Master Gardener who lives in New Jersey and has so many great gardening ideas no matter what the season.
For some great tips to save plants over the winter, visit my friend Rachel of The Ponds Farmhouse where she uses her gorgeous greenhouse to overwinter her plants.
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Love your tips on saving and storing the dahlias. I am going to do it this year since I’m having a lackluster season with my dahlias. And thanks for sharing my post ! xoxo
Ingrid Sisson says
Can I grow dahlia in the pot? I never grow dahlia, I would love to try this flower this year. What is the best month to start plant it? I got black dahlia bulbs online. Thank you.
Your garden looks magnificent ?
Jennifer Howard says
Thanks for this! I need all the tips! I didn’t realize you were in zone 8…that sounds dreamy!!
Rachel Harper says
Kim, I loved this information! Hope to plant some next spring. Pinned so I’ll have the information
I will be so excited to see you grow dahlias Rachel. It is so wirth it!
Great info Kim!!! I’m hoping mine make it this winter. I’ve overwintered other tender bulbs but never dahlias. Your flowers always look spectacular.
I am so excited that you are growing dahlias now Stacy. Now we can compare notes.