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5 Steps To Divide Dahlia Tubers

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Everything You Need To Know to Successfully Store Your Dahlias Over Winter

divided dahlia tubers in vermiculite
Dahlia tubers that have been divided and are ready for storage.

In many areas of the world, you have to manually dig up and store your dahlia tubers over the winter. Dahlia tubers do not typically survive in growing regions below 7. Cold and wet winters will cause your tubers to rot in the ground. If you’re new to dahlias or you’ve never dug up your dahlia tubers before, this post will help you with five steps to divide your dahlia tubers for next season.

Even if you live in a growing region where dahlia tubers can survive in the ground over winter, it’s still a good idea to dig them up every few years and divide your tuber stock. The mother tuber (the initial one you planted) will eventually begin to decay and it will not produce as many blooms. Dividing your tubers allows for new growth each season and for your tuber stock to remain healthy.

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Multiply Your Dahlia Tuber Stock By Dividing Dahlias

Digging up dahlia tubers is a tedious process. However, you will be rewarded with even more viable tubers for the following summer! Dahlia tubers are expensive. One of the best ways to multiply your stock is to dig up your tubers at the end of the growing season and divide them. One healthy plant can give you anywhere from 3-20 new tubers for the following season!

Preparing to remove your dahlia tubers from the ground

Most people prefer to wait to remove their dahlia tubers from the ground until after their first killing frost. You will know when you’ve had a killing frost because your dahlia plants will be black in the morning and your growing season will abruptly be over. However, once your dahlia tubers have been in the ground and growing for at least 120 days, you can actually dig them up for storage. I used to always wait for our first killing frost, but now that I grow over 500 dahlias each season, it’s a long process to get them all out of the ground. If I have not had a hard frost by mid-October, I begin removing mine from the ground to prepare for winter storage.

What You need to dig up your dahlia tubers

clump of dahlia tubers
Clump of dahlia tubers just removed from the ground.

To prepare to remove your dahlia tubers from the ground you will need the following:

Before any chance of a killing frost, you will want to make sure that your dahlia tubers are labeled. I like to use garden labels to put around the base stem of my tubers. On the label, I use a Permanent Garden Marker to write the name of each variety so I know which variety I have.

daughter helping clean up the dahlias
My sweet little garden helper helping me clean up the dahlias before we remove the tubers from the ground.

You will also want to make sure that you have a pitch fork and a good set of loppers for removing your dahlias from the ground. I prefer to use a pitch fork over a shovel as it allows me to gently lift the tubers from the ground. The loppers make cutting the dahlia plant down so much easier!

Removing Your Dahlia Tubers From The Ground

cluster of dahlia tubers dug up
Dahlia tuber clumps just removed from the ground.

It’s time to remove your dahlias once you’ve either had your first killing frost OR your dahlia tubers have been in the ground for at least 120 days. The first thing you will want to do is cut back your dahlia plants so that you have about 6’’ of stem remaining on the plant. This will make it easier for you to grab the plant with a handle when you remove it from the ground.

Once all dahlia plants have been cut back to only 6’’ of stem remaining, it’s time to start removing the tubers from the ground. Using your pitchfork, gently put the pitchfork into the ground (I like to be at least 10” from where the dahlia stock is. Gently rock the pitchfork back and forth until you’re able to lift the clump of dahlias. Once you have the clump out of the ground, carefully shake off the excess dirt. You want to leave some dirt around the tubers to help retain moisture.

You can watch my remove a clump of dahlia tubers in the YouTube video below:

How To Clean Your Dahlia Tubers

Before you can divide or store your dahlia tubers, you will need to clean them first. This is a messy process so I suggest wearing clothes that are waterproof and that you don’t mind getting wet. I like to also wear a waterproof pair of heavy duty gloves. You will need a hose and a good hose nozzle to spray off the dahlias. Be careful not to spray at too high of a setting as you can break or damage the tubers. Watch my YouTube video below to see how I clean my dahlia tubers.

How To Divide And Store Your Dahlia Tubers

What You Need to Divide & Store:

Once you have washed your dahlia tubers, it’s time to get them ready to go into storage. I like to divide my dahlias before storing them, but you can also wait to divide them in the spring. My dahlia tubers are stored in plastic containers with vermiculite. You can also store your dahlias in peat moss. Don’t store your dahlias in cardboard boxes as the cardboard will suck the moisture out of your tubers.

Dividing Your Dahlia Tubers To Increase Your Tuber Stock

You can divide your dahlia tubers in either the winter or springtime. You may want to wait until spring when the tuber eyes are more visible. To get started you will want a clean workspace, a good pair of garden scissors, cinnamon, and bleach. I bleach my tools between each set of tubers to make sure I don’t spread any potential disease.

Your one dahlia tuber from last spring has likely produced additional tubers. Most of my dahlias produce between 5-20 new tubers each season (some varieties produce more than others). When you divide the tubers, it is important that each tuber has part of the original tuber stock along with a neck, body and eye. Without these parts, you will not be able to grow a new dahlia plant.

I like to start by dividing my tuber clump in half. This allows me to get in and divide the tuber clump into individual tubers. To see this process, be sure to watch the YouTube video below as I show you how i divide a clump of tubers. Dip the cut portion in cinnamon as this helps to prevent any bacterial or fungal growth.

Once your dahlia tubers are divided, it’s time to put them in your storage containers. I line my plastic bins with about 2” of vermiculite. Then I place my tubers in the container (with the eye face up). Once you have a layer full, cover it in vermiculite and repeat. Your plastic bins should be stored in an area that has temperatures between 40-50 degrees. You do not want your tubers to freeze.

Periodically check your dahlia tubers for signs of rot

You should periodically check on your dahlia tubers over the winter. Check for any signs of mold or rot. If you find any, immediately remove those tubers from the container.

I know that all of this seems like a lot of work and effort. Trust me, it’s well worth it in the end. Dahlia tubers are expensive. The best way to increase your stock is to store and divide your tubers each year. If you find you have some extra, I’m sure your friend or neighbor would be grateful to receive any extra tubers you have.

I hope that you’ve found these steps helpful in understanding how to store and divide your dahlia tubers. Be sure to grab your FREE checklist below with tips for storing and dividing your dahlia tubers. If this was helpful, I’d love to hear from you in the comments below! You can also help by pinning this post to Pinterest. And don’t forget to check out our Dahlia Tuber sale where we will have over 30 varieties of tubers for sale. Happy Gardening!

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  1. New gardener alert. I grew dahlias 2 summers in a row and this was my first year digging them up to divide (Seattle- zone 8b) and your blog and videos helped me so much! Finding the eye is hard. Oh man I hope I did it right. If not, I’ll be back next season. Thanks for your detailed notes.

    1. Katie that makes me so happy to hear that my blog and videos helped you dig and divide your tubers. Sometimes it can take awhile for the eyes to wake up. Let me know how it goes!

  2. Growing Dahlias is a rewarding experience. I remember planting my first ones when I was just 6 years old, and it brings back memories of the cool summer nights in July that always seemed to be filled with adventure even though there were only two people at home; me and mom.
    ShunCy recently posted…How to Grow a Chestnut Tree from a ConkerMy Profile

  3. Thank you, first time I have grown them. Hopefully my tubers will make it through the winter.

  4. Your video’s helped me so much. Thanks for you information. I live in Burlington Washington. My mom passed in December and dahlias were one of her passions.

    1. I’m so sorry to hear of your mother’s passing. I’m sure dahlias will bring you special memories of your mom!

  5. THANK YOU Really found your teaching skills very helpful. I am a new year so will wait to divide early spring. Central coast Californiazone 10 b with no frost…so an I plant out in February ?
    Peace and joy. Jackie

    1. Hi Jackie, you don’t want to plant until your soil is at least 55 degrees. Be sure to check out my beginner’s guide to growing dahlias.

  6. I live in Zone 7b in North Carolina, apparently warm enough to over-winter happy dahlias. I am guessing that it isn’t necessary to go through the whole rigmarole of storing tubers out of the ground over the winter, here BUT… I do want to divide the Older ones, and it’s not clear to me whether I should do that now, sometime in the winter, or when it’s warming up in the spring… Got any clues for me? (It does seem like the eyes would be more apparent after a winter in the ground?)
    Anyway… Any suggestions would be gratefully received!

    1. Hi Mark, if you can leave your tubers in the ground (which is risky in zone 7b) then you can wait until spring to lift and divide. Eyes will be more visible in the spring.

  7. Thank you for the information but if I want to divide in the spring how do you store them to divide later?

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