What to do when stored dahlia tubers sprout early?

Garden Making

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Dahlias in summer 2017: Saving the tubers over the winter.
Dahlias in summer 2017: Saving the tubers over the winter.
Dahlias in summer 2017.

Michael in Niagara-on-the-Lake, Ontario, asks:

Dahlia tubers that were stored in peat moss in the basement have started to send up shoots. They’re  in the coldest part of the basement, but it is 14 to 16°C in the room with about 35% humidity. Should the sprouts be trimmed off? Left alone?

ahlia-tubers-in-storage-Jan-2018
Early sprouts on dahlia tubers stored in bins of peat moss in the basement. They’re moving into the garage.

Nick Vanderheide of Creekside Growers in Delhi, Ontario, says:

The issue at hand is really the storage conditions. Dahlias will sprout under warm, damp conditions, and anything above 10° C is considered warm. The humidity level of the room may very well be 35%, but do you know what the humidity is in the peat moss? You want to maintain a decent amount of moisture in the tubers (not the media it’s stored in) so at 35% room humidity, it is a good thing to put them in peat moss to prevent them from drying out.

Heat is the big deciding factor in sprouting. Spring soil temperature is usually around 12 to 16°C when we plant and that causes the tubers to sprout, so if they are in a room at that temperature they will definitely start growing. In the Netherlands, this sprouting is actually how new, true-to-type, dahlias are produced. The tubers are forced indoors to produce little shoots which are then cut off, rooted and grown as plugs to then plant in the field for the summer where they will produce a new tuber that can be harvested in the fall.

The shoots on your tubers can be trimmed or not; they will not affect the viability of the tuber come spring time. One thing to consider, though, is that the tuber is simply a storage organ for the energy it needs to grow come spring time, so if your tubers continue to try to grow, they are using up energy that they need in the spring to become a big, healthy plant.

I would strongly suggest getting those dahlias into a colder area to slow down that sprouting. And then stop worrying—spring is only a few short months away!

More about dahlias

How to divide and store dahlia tubers

When and how to store dahlias and cannas

 

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7 thoughts on “What to do when stored dahlia tubers sprout early?”

  1. It’s nearing the end of May and the temps have been in the high 70s here in Indiana. I got my tubers out of storage for the first time today and they have begun sprouting, not long and leggy sprouts, but short healthy ones. I missed the window to pot them up so my questions are: Do I remove the shoots or leave them on and still plant them 4-6” deep? And is it okay to water them after I plant them?

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  2. My dahlias have long white sprouts after the winter storage. They are too long to grow. can these sprouts be cut then planted up or placed in water to root. Which is better.

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  3. Thank you, this article is helpful. All my dahlia tubers, stored in their pots in a heated shop to keep them from freezing, have started to grow healthy-looking, green plants. I am going to move the pots into our crawl space, which will be cooler, but above freezing. I wonder, is February too early to start dahlias indoors, if I give them enough light?

    Reply
    • Hi Nicole …if you already have healthy looking green plants I can’t recommended enough using those as cuttings ! …(and Google ‘rooting dahlia cuttings’)…. That’s what I did when mine started growing too early. I’m in Ontario and usually start sprouting mine indoors Early-middle of March so that I don’t have to wait till September for flowers. This way I am putting out at least a 6 to 8 inch tall plant as soon as my soil is warm enough in June -because I have such a short growing season here in zone 4b.

      I already have a couple of tubers putting out shoots now in the middle of February -which is too early -and I need to make them colder I guess ! because I don’t want to steal energy from the tuber (it is still a bit too soon for me without a good greenhouse or advanced grow light set up, to start mine). I count back 2 to 2 1/2 months before last frost date to know when to start mine indoors. Hope that helps a bit! I learned how to take cuttings and multiply my tubers that way, because some specialty dahlias can get very expensive for me with shipping etc. and I want to make sure I have a copy in case one plant fails.

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      • Hi Wendy. I started my tubers last week in Zone 5 (NB). Planted 42, and already 20 of them are up through the soil, and a couple at 2-3 inches high already. At this rate they will be eight inches tall well before the frost has gone. I have them under grow lights in our cool basement….likely around 17-18 degrees C. Is there anything that i could/should do to slow them down a bit??

        Reply
      • Hi Wendy. I started my tubers last week in Zone 5 (NB). Planted 42, and already 20 of them are up through the soil, and a couple at 2-3 inches high already. At this rate they will be eight inches tall well before the frost has gone. I have them under grow lights in our cool basement….likely around 17-18 degrees C. Is there anything that i could/should do to slow them down a bit??

        Reply
      • if you’re getting sprouts or roots (I’ve got things of all colors sprouting from the remainder of the center stem stub, from the lenticels – white shoots from those areas, and even some pink-purply ones on the stem) too early and you put them into a cooler spot, will it kill off what is growing and then sprout more places come spring??
        I’m having this happen in December after only a month in storage. Too warm in basement and too moist, but I still don’t know what kind of crazy is happening to these. LOTS of white shoots/roots and the lenticels, and finally the stem !

        Reply

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