When to Split Dahlia Tubers - Now or Later?

A view of a few of our abundant dahlia rows in 2023.

Updated March 11, 2025

(originally written in November…) November is here, bringing the chill of early Winter in the Northeast and Midwest regions of the United States. For a cut flower grower, it’s dahlia digging season!

So once you’ve dug up your dahlia tubers, what should you do with them? Should you split them now, or leave them whole and split in the Spring before replanting? And beyond that: How should you store your dahlia tubers?

In this article, I’ll cover the reasons why you would consider dividing your dahlias now vs later, and the risks involved in splitting dahlia tubers right away.

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Should you divide dahlias right after digging them up?

First, I’d like to acknowledge that there are hundreds of ways you can do anything (especially garden-related tasks), and quite frankly, there is no one right or wrong way for you to approach dahlias at the end of the season. This includes digging, splitting, and storing dahlia tubers. There are definitely mistakes you’ll want to avoid when storing dahlia tubers, that is for sure; however, when it comes to the timing of splitting them, I’m not going to judge for you whether you should do it right away or not.

The ONLY reason I split dahlia tubers right after digging them is because I have thousands of tubers to store and split/divide. I split as many as I can right away because that means less mess later on, when I have to split the remainder of them during winter months.

If you are growing dahlias on a “smaller” scale (300 or less), I would advise keeping them whole until late February through March. I’ll explain why, below.

Side Note: Our Dahlia growing manifesto

I recently wrote a book all about growing dahlias called Growing Gorgeous Dahlias: The Regenerative Grower’s Guide to Abundant Dahlias from Garden to Flower Farm, there is an entire chapter on digging and storing dahlia tubers with another entire chapter on splitting dahlia tubers. For both beginner and experienced growers, I recommend getting yourself a copy or asking your library to purchase one for you to borrow!

Growing Gorgeous Dahlias: The Regenerative Grower's Guide to Abundant Dahlias from Garden to Flower Farm Buy on Amazon

Advantages of splitting dahlias right after digging

There are a few advantages for growers to split dahlia tubers right away.

If you are growing dahlias on a “large” scale (300 or more), dividing your dahlia tubers right after digging will allow you to get a head start on the massive amount of work required to split all of the tubers;
Splitting dahlia tubers right away will let you know your tuber counts for next year (assuming they all survive during storage — I always assume 10% loss to be safe);
Split tubers take up less space than whole clumps, so again, if you’re growing on a large scale, splitting right away will save space and the amount of bins/crates you’ll need to store your tubers.

It’s obvious that the advantages to splitting dahlia tubers right away are mainly geared for large-scale growers.

Are there risks for splitting dahlias too early?

There is one main reason I would suggest that “smaller” scale growers keep their dahlia tubers whole until late Winter or early Spring, and that is the potential for desiccation (drying out). When you split your dahlia tubers into smaller pieces, they are more susceptible to desiccation.

Indeed, desiccation is highly dependent on your own storage conditions (temperature, humidity levels, and method of dahlia tuber storage); however, if you don’t have a familiar hold on your dahlia tuber storage process, I would err on keeping your dahlia tubers whole until 2-3 months before you intend on planting out.

so then, if not after digging, when should I split my dahlia tubers?

If you need to get ahead of the game (you’re growing a considerable amount from 100-300 tubers), then I recommend starting to split 2-3 months out from your planting date. You’ll want to plant dahlia tubers after all danger of frost has passed in your USDA Hardiness Zone. After splitting whole tubers, simply pack them back into your original storage/packing medium.

If you are are growing dahlias for fun (ie. you don’t have a business where growing dahlias is all or part of your income), then you might wait to divide your dahlia tubers until 1-2 months before planting. Again, this is simply a suggestion to make sure your dahlia tubers do not desiccate during storage. Please do what is comfortable for your level of dahlia growing expertise!

I hope this has cleared up some confusion over whether you should divide your dahlias right after digging or divide them later on. Obviously, there is no straight answer, but as an experienced dahlia grower and dahlia tuber producer, I would recommend keeping your dahlia tubers whole throughout the Winter unless you are growing on a large scale and/or have your dahlia tuber storage process completely under control.