How to Dig, Divide & Store Dahlia Tubers.

If you’re lucky you live in an area where you don’t have to dig up your Dahlia tubers.  For the rest of us we must dig, divide and conquer.  And it’s time to do that right now. 

Now that the weather has turned and what was previously green and lush outside is now black and rotten, we all want to just turn off our gardening brains for a while and sink into the sofa while Instagramming pictures of our clean nails. 

So it’s with great sorry that at this time every year I have to lug myself outside in winter clothes to dig up the dahlia tubers. Some years I kind of hope the tubers just up and die on me. And sometimes they do.

Three years ago, despite all of my efforts, I could not kill my dahlia tubers over the winter. I stored them improperly, ignored them and silently cursed them.  I’d have given them the evil eye if I believed in that sort of thing but I don’t, so I stuck with a garden variety exorcism.

No luck.

At the beginning of April I opened up my plastic bags of Dahlia tubers expecting to find a wrinkled mass of nothing and found perfectly fine tubers.

This goes to show you that dahlias have a mind of their own. You can store them improperly and have them either rot into a putrid mess or shrivel up into a fossilized version of a tuber. Or. They’ll turn out just fine.

Dividing and storing dahlias can take place any time between now and the spring, but you have to get them dug up after the first frost no matter what.

Luckily you don’t need a lot of dahlia tubers to produce a lot of flowers.  You can see the mountain of Dahlias 10 or so tubers produced in this post

And dahlias multiply QUICKLY.


In one season, a baby finger sized tuber will grow to the size of something you could base an entire horror movie around.


Tubers grow like hands with multiple fingers. Each finger can get separated, cut off and planted next year.

That one tuber you bought could end up being 10 tubers after just one season. And they KEEP doing it. Every year you plant a small tuber it grows huge, you split it and you’ve increased your stock yet again.

I’m not an expert but I’ve been doing it for a few years now so I feel confident that I can walk you through it if you’re worried.  

Digging Dahlia Tubers

Tubers are easily broken, so be careful when you’re digging them up. You don’t want to injure or lose any of the fingers. 

Cut any stalks back so there’s only about 6″ of them showing. This way you can still see where the plant is, but the stalks won’t be getting in the way.  It will also give you something to hold onto when pulling up the plant.

Using a shovel or fork dig about 1′ away from the centre of the plant loosening the soil. Pull the plant straight up once you can feel that it’s released from the soil.

Label the tuber immediately. I have a bamboo stick pushed into the ground at the base of each dahlia plant. The top of it is split which holds a plastic tag and wire tightly throughout the season. When it’s time to dig the tubers up, I have the wired tag right there to grab and put on the clump so I don’t lose track of what kind it is.

 

Wash the soil off with a garden hose and set it to dry.  I use a rack made out of hardware cloth set onto a small adjustable workbench. I put the tuber on top and spray with the hose so all the water just falls below.

Set the cleaned tuber aside outside to dry until the next day.

How to Split Dahlia Tubers

The gist of it just involves cutting each finger off and making sure there is at least 1 eye on each of them. Tubers can be divided right after digging them up like this or in the spring.

Because they’re so big when they come out of the ground they’re hard to store. Splitting them in the fall (and not the spring) eliminates that problem because they take up much less space once they’ve been divided.

 

STEPS

Move onto dividing the tubers once they’ve been dug up, cleaned and allowed to dry for a day.

1. Remove the stringy, withered tubers that will never amount to anything.

I use these Felco pruners

See? That’s not going to do anything for you.

 

2. Once you get all the extraneous stuff trimmed away you can better see what you’re working with.

3.  If there are any tubers growing off of other tubers, cut those off and throw them away.  Those piggy back tubers will never produce Dahlias.  The big main one will, just not its parasitic twin.

4.  Dahlias sprout from eyes on the very top of the tuber necks.  So start cutting off each tuber, making sure to include enough of the neck that you get some eyes.

5. Immediately label the tuber by writing the variety on it with a Sharpie. You can also tag it by tying it with flagging tape.

 

Parasitic tubers like this can be cut off.

The eyes are much easier to see for dividing in the fall when they’ve just been dug up. 

If you chose to divide them in the spring, if you’re lucky, your Dahlia will have already started to sprout which makes spotting the eyes easy.  They’ll have a stem coming out of them.  Or they’ll be swollen enough that you can spot them like in the photo below.

 

To reiterate, I’m not an expert – I’m just a girl with a pair of clippers.

 

Once you’ve decimated the horror show of tubers,  you’ll have several individual, viable tubers for planting or giving away the next year.  This compounds year after year until eventually you  have enough Dahlias to start your own free love hippie compound.

Storing Dahlia Tubers

If you’ve split the tubers and let them heal and dry for a day you can go ahead and put them into either plastic bags or boxes with vermiculite. You don’t need to fill the bag or box. Just enough to give the tuber a good blanket of vermiculite to help keep it from drying out or rotting.

You can add more than one tuber to a bag as long as they’re not touching and are separated by a layer of vermiculite.

Remember : Tubers must be completely dry before storing them or they’ll rot.

Store tubers somewhere that’s 10 degrees celsius (50 degrees F) or below.

You can pot them up under grow lights a couple of months before you plan to plant them out so they get a good head start.

How to Divide & Store Dahlia Tubers.

How to Divide & Store Dahlia Tubers.

How to divide and store dahlia tubers for the winter in colder climates.

Materials

  • dahlia tubers
  • coarse vermiculite*
  • tags
  • sharpie marker
  • tape
  • pruners

Instructions

    1. Dig up Dahlia tubers 1 week after they have been killed by frost. On that same day wash and label all of the tubers. LABEL AS YOU GO OR YOU'LL GET THEM MIXED UP.
    2. As you dig up the tubers, wash all the dirt on them away with a hose. It's a cold November job.
    3. Allow the clumps to dry for a day before dividing them.
    4. On tuber dividing day remove the stringy, withered tubers that will never amount to anything.
    5. If there are any tubers growing off of other tubers, cut those off and throw them away.  Those piggy back tubers will never produce Dahlias.  The big main one will, just not its parasitic twin.
    6. Once you get all the extraneous stuff trimmed away you can better see what you’re working with.
    7. If it's a very big tuber with lots of fingers, it's usually easiest to cut the entire huge tuber in half so you're working with a smaller bunch. It's O.K. if you have to sacrifice a few eyes to do this.
    8. Dahlias sprout from eyes on the very top of the tuber necks. If you split your tubers a day after digging them up the eyes will be more prominent. Waiting even a few days will result in the eyes shrinking, making them hard to see.
    9. Start dividing and cutting off each tuber, making sure to include enough of the neck that you get some eyes.
    10. Write the name of the variety on the tuber with a Sharpie as soon as you cut it off of the mother plant.
    11. Let the tubers dry another day to allow the cut wounds to heal and dry then store them in either an open plastic bag filled with vermiculite (label the bag as well) or in a plastic bin with vermiculite.

Notes

*coarse vermiculite is larger than regular vermiculite and helps prevent moisture build up around the tuber.

For individual tubers, sandwich bags are perfect because you can write the name of the variety on the bag and use them over and over every year

Dahlias can seem overwhelming because they do need a bit of work – what with having to dig them up, curse them, and replant them every season. They demand attention, you can’t just plant them and forget them.  Don’t let their bossiness stop you from growing them though.  Divide … and conquer your Dahlias.

 

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How to Dig, Divide & Store Dahlia Tubers.

44 Comments

  1. Leah Bonebrake says:

    Dahlias are SO worth the trouble!

  2. I didn’t divide my dahlias in the fall. This spring I planted all the attached tubers in pots inside my home. There are now multiple growths and lots of leaves (really, I thought they all died but everything is growing). Is it possible to separate them at this point?

  3. Ellen says:

    I have stored some tubers (as per this post) and I haven’t dared look to see how they’ve fared, but when I do, I am wondering when they can be planted back in the garden? I live in Toronto, Ontario.

  4. Petra says:

    Yup, today is Tuber Dividing Day. I don’t meticulously divide down to singles but make sure I separate the clumps enough so that air can circulate and dry them enough. This means prying them apart with two garden forks, making sure there’s no damp dirt hiding in between. These are huge galaxy clumps. I totally agree with removing withered, mushy or otherwise pocksey lookin stuff. The idea is to keep your dahlias healthy and though they are really tough, in some soils and climates they can get diseased. It might not kill them but can weaken them so the flowers they produce become smaller, less colourful, etc. My tubers overwinter in covered tubs of dry peat. I think they are totally worth the fuss.

  5. Jane says:

    Karen,

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