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.

38 Comments

  1. 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.

  2. Jane says:

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  3. betty says:

    i have some dahlias that were in storage from winter and i planted them as is in a pot inside the house . It is now mid april and they have grown about a foot and have many shoots. Can i split them up now and plant into different pots.

  4. Teri says:

    I live in Alaska and grow beautiful Dahlias in pots. In fall I cut them all the way back and put pot and all in the garage. I then pull them out in spring, separate and replant in the pots and resell the others at market:) the reds are my favorite!

  5. katie says:

    dug mine up this year cant make head nor tail of them. but i know a little now from the posts.
    is it ok to plant in large planter because i would have to keep moving it to get enough sun i live in ireland no way would we get 8 hours of sunshine every day, we are lucky to get that in a year (joke). great to get all the tips

    • Karen says:

      Hi Katie! I’ve never done it but I don’t see any reason why you couldn’t grow the dahlia in a pot! Just make sure it’s large enough. That tiny little tuber turns into a great big tuber by the end of the season. And make sure the soil has plenty of compost and/or fertilizer so it has enough to feed on through the season. Then replenish the nutrients every year. ~ karen!

      • Donna says:

        I had great luck growing them in containers. I’m in the USA, zone 7. Didn’t have any luck storing them over the winter, so am starting fresh this year. Thanks for the tips. I wish I could just bring the pots in for the winter and take them out in the spring!

      • Sam says:

        Hi Karen,

        I farm dahlias and you’ve given some false info. Those tubers growing off another tuber… don’t throw it away and yes they will grow. Same goes for the stringy ones that you said to toss to get to the main ones. They will grow. You cannot kill dahlias.
        I live in a very wet and cold climate and never get them out of the ground (other than to split). They multiply like mad and the size of the tubers means nothing.

        • Karen says:

          Hi Sam! I understand the size of the tuber means nothing, but if it’s dried up like a raisin with no eye it’s not gonna grow right? That was the case with the shrivelled one. I’m not sure where you’re from but you definitely can’t leave them in the ground in most of Canada. I’ve tried just for fun a couple of times and it ended up not being fun, lol. All I ended up with was lost tubers. As far as the parasitic ones, if it doesn’t have its own eye how does it sprout? ~ karen!

        • Nancy Ann Page says:

          I live in zone 9B in Florida. Will they grow here?

          Nancy Ann

  6. PK says:

    I started with ten tubers.I now have plants with 50 tubers every year.I am at the point where I should dig every fall but I don’t dig them all up.I cut them back and dig and separate different ones each year. I replant the same day.I dry some over the winter but normally just plant and throw grass mulch on top.I’m on West Coast of Canada. Snow is very rare here and ground stays warm enough.Most of the tubers i dry,I give away.I could not begin to find places to plant them all them.many of mine are (were) 8 ft. until my wife murdered them.Beautiful flowers but they do need work.Water from the bottom as the Flowers don’t like water. It is now August and I’ve watered my large plants about 5 times since June. You can’t kill them

    • Karen says:

      I killed some! This summer, up at my cutting garden I water automatically and what was great for the vegetables ended up being WAY too much water for the dahlias and a lot of them rotted. :/ Luckily the ones I planted at home grew huge so I’ll still have a billion tubers for storage. ~ karen!

  7. Anne says:

    I love dahlias. I’ve got some that I’ve had for years and a few others that I couldn’t resist at plant sales or someone’s given me. I put mine in boxes, no covers, and put them in our not-very-big pump house. If we get a cold spell in the winter, we put a light bulb in there and it seems to be just enough to get them through. I plant almost every little bit that looks like it might grow, lots I start in pots, and those that I end up not having room for, go on the side of the road for anyone who wants them.

  8. ~Renae says:

    Dahlias are the zucchini of the flower world, so much bang for the buck! I do find them to be a little terrifying though…the earwigs love to hide in them. God, I hate earwigs.

  9. Christine says:

    Hi Karen,
    Do you plant your dahlias in a lot of sun? Also do you put anything special in the planting hole?
    I grew dahlias last year. We live in Minnesota so I dug them up last fall and, of course, the tubers rotted out and became moldy over the winter. So I ordered some more this year and they just arrived.
    I did not get a lot of flowers on them last year so I’m wondering what is your secret!

    • Karen says:

      Hi Christine. Yes, full sun. I never do anything special with any vegetables or flowers other than laying compost onto the soil before planting. 1-2″. Don’t dig your tubers up until the leaves have gone brown and dead looking. Also cut them! The more you cut the more they grow. For bigger blooms you can pinch them. Dahlias grow with 3 shoots per stem. Two side flowers and one centre flower (which will always be the largest). Pinch off the two side shoots for a big flower and to encourage more flowering. ~ karen!

    • PK says:

      Christine,dry them in a bowl or box of peat moss to take away moisture and prevent rotting.Many tubers are actually sold this way.

  10. Julie says:

    If dividing your tubers seems too complicated, you can just dig a hole and plant the whole big withered thing! It works fine for a few years! Then you can just hack the clump in two…no need to make it too complicated! Of course if you want to have an acre of dahlias, you would probably need to carefully divide the tubers!

  11. Emily says:

    Where did you store the tubers during the winter? I don’t have a garage so the basement would be my only option.

  12. Sharon says:

    I’m a fan of dahlias, except the staking, digging, and storing part. I never got the knack of staking them attractively. They always seemed to sprawl. How do you stake them? I left mine in the ground thinking they would die, but despite some very cold winter days, they are coming up and begging to be taken care of.

    • Karen says:

      Hi, Sharon
      We use tomato cages to stake our dahlias in Oregon. :o)
      blessings on your day!

    • Karen says:

      Because these were for cutting and not in a “pretty garden” I didn’t stake them at all, lol. I just let them do their thing which is risky because they break easily. They did fine though. My guess is one of those rings that normally go around Peonies would be a good thing to use for Dahlias. ~ karen!

    • Randy Lacher says:

      I put tomato cages around mine and that works great. Be sure to get the taller cages to protect the stems of the taller and larger variety of dahlia. Mine are in huge pots as well.

  13. Elizabeth says:

    Well this is timely. I just pulled out my probably-not-stored-correctly-tubers out of the cupboard just this morning. I was surprised to see an inch long green growth coming out of one of them.

    This is my first over winter storage and my first replanting. Crossing my fingers.

    Now off to find out what to do with my grapevines and hoping I am not too late do have done something by now.

  14. Sabina says:

    My mom always had the green thumb for dahlia’s, I’m embarrassed to say I’m intimidated by the whole digging up and storing task. They’re just so beautiful though. I’m wondering how they’d do in a big planter and then rolled into the garage in the winter…

  15. Marilyn says:

    I just bought two at a garage sale ! Hoping for the best..

  16. Susan Claire says:

    I bought dahlia tubers one year, planted them, waited in vain for beautiful flowers, and then realized that I had just supplied the gophers with some very expensive appetizers.

  17. Ev Wilcox says:

    NO NO NO NO NO! I am struggling enough with all the daffodils that need separating. You guys just go on, have fun, blah blah blah, etc.! thanks anyway Karen!

  18. Kathryn says:

    I’m picking up a bag of Dahlia tubers from a friend who has too many at lunch today. Now I see what I’ve signed up for.

  19. danni says:

    I had been eyeballing dahlia tubers at the local mega hardware store but managed to control myself until that last post about them. Now we will see just how bad/good it gets. ….
    I’m a sucker for overachievers. Which omg now that I think of it the damn luffa vine was last year! Oh what have I done!?!?
    (Karen, if my mom were alive she would not be letting me hang with you! Bad influence!)
    (Pffft, like that would deter me!)

    • Karen says:

      That’s me! Terrible influence. ;) My luffa plants are HUGE, ready and waiting to be transplanted in the next few weeks. Maybe I’ll plant them near the dahlias and watch them fight over territory all summer. ~ karen!

  20. Jenny W says:

    I think I need you to draw an arrow pointing to the eye, cause both ends look the same to me :/

  21. Paula says:

    You are right – that size wouldn’t do anything for me.

  22. Tina says:

    I have a friend whom I have found to be the Dahlia King of Oregon. I am always amazed at how many acres he gets of these massive flowers! This year I bought a few, I plan on challenging y’all in a couple of years!

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