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Cold Climate Tips for Getting Your Dahlia Tubers Ready for Planting

Category: How-To Projects, Plant Ideas & Info, Presenting "The Curious Gardener"


We spoke with Lisa Ringer of Two Pony Gardens in Long Lake, MN about how she prepares for the dahlia season. Many parts of the country are experiencing a late spring, so her advice on how to lengthen the growing season is particularly relevant this year, even to non-Minnesotans.

Here’s what she told us, commenting that she has two feet of snow on the ground and it’s the middle of April (!)  This is not typical, even for Minnesota.

Since Lisa’s growing season can be cut short by a mid-September frost, she does some things to ensure earlier dahlia blooms.

“In early April I pot up my tubers in gallon pots with a soil-less mix with lots of bark in it,” she says.  “I haul the crates out of storage, leave them at room temperature for a week or so before I plant them to let them wake up. That way I can see which tubers have eyes, which just look like tiny bumps. I sprayed all the dirt off in the fall before I divided them.

I like to pre-start the dahlias. I have the luxury of a ‘rustic’ hoop house, barely heated to fend off nighttime frosts. I think a barely heated garage would work also. It seems to take weeks for shoots to finally appear. I keep them pretty dry until they are actively growing with the warming days. I like to do it this way because once planted in the ground I can see where they are in the chaos of my garden.

Because I grow over 600 plants I divide up the clumps in the fall to capitalize on storage space. I store about 7 cut up tubers of one variety in an unsealed plastic gallon storage bag with a handful of slightly moistened peat moss (with a pinch of cinnamon mixed in to stall off rot). They are placed in alphabetical order ‘Akita’ to ‘Zorro’ in black plant crates that are easy to stack, label and store. 45 degrees is the optimal temperature. I check stock midwinter to check for rot or dehydration.”

Dividing  Tubers

Whether you divide your tubers in the fall, as Lisa does, or in the spring, the key is finding the eyes and making sure each tuber has at least one. Lisa says “It is hard to believe that all one needs for a big husky plant is one single eye on one single tuber.”

After getting Lisa’s advice I pulled my own tubers out of the box they were stored in over the winter. I had not divided them so I started to look for the eyes as I prepared to divide them.  I found it quite difficult to identify the eyes. Here is my guess on one of the tubers I cut apart from the clump. I put this question out there for anyone who wants to answer it:  “Is this an eye?”



4 thoughts on “Cold Climate Tips for Getting Your Dahlia Tubers Ready for Planting

  1. Marianna Amato says:

    Its hard to tell but could be. Usually the eye is close to the neck of the tuber.

  2. Marianna Amato says:

    Now that I see it on the larger photo I have to say NO.

  3. I live in zone 5 b. would like to dig and separate my dahlia tuber clumps, which have been in the ground for three years. I have never dug them out for winter and they happily come back in summer

    . Most of the websites tell me to dig and divide dahlia tubers in the fall. Curious to know if I can dig them out in April, divide them and sow them right away in ground for summer blooms.

  4. I think this clump does have an eye. If you look straight down from where you have the arrow pointed I can see a little ‘pimple’ that is most likely an eye. That is the area where the eyes usually form – between the stem and the tuber.

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