Dividing Dahlia tubers

It’s always a great time to work with your Dahlia tubers. Whether you’re bringing them out from winter storage or preparing them in another season, ensuring they are firm and solid is key. By dividing them, you can get more plants for your garden or share them with friends and neighbors. In this post, we’ll share some simple tips to help you succeed in dividing your Dahlia tubers. Happy gardening!

Delade dahliaknölar

Our 5 best tips for successfully separating your Dahlia flowers

Divide or split Dahlia tubers in spring or autumn?

You can divide Dahlia tubers in both spring and autumn. However, dividing them in autumn, right after they’ve been dug up, carries some risks. The tubers may not be fully dormant and are more delicate, plus there’s a risk of them molding at the cut surfaces.

That’s why we recommend dividing Dahlia tubers in the spring, after their winter dormancy. By then, you can assess how well they’ve fared over the winter and avoid unnecessary effort in dividing.

1. Trim Away Any Moldy or Soft Spots

Use pruners or a sharp knife to remove any moldy or soft spots on the tubers. Even very dry tubers might still have life in them, so it might be worth taking a chance and keeping them.

The Dahlia in the picture here has nice, firm tubers. If yours look like this, it’s very promising.

Dahlia efter vinterförvaring

2. Locate the “Eyes” of the Dahlia

The growth points of Dahlias are usually called eyes, similar to potatoes. These growth points are where the tubers are attached in the cluster. The area where a tuber is attached is often slightly swollen and ring-shaped. Gently feel over that area; the eyes feel a bit different, soft and smooth compared to the rough surface of the rest of the tuber.

Sometimes, the growth points aren’t visible because they’re dormant. In that case, place the Dahlia in a bright, warmer spot for a few days to awaken the growth points and make them more visible.

When dividing a tuber cluster, each part must have at least one tuber and one eye for new shoots to develop and grow into a new plant.

Öga och skott på dahliaknöl

Eye and shoots

Öga på dahliaknöl


Ögon på dahliaknöl

Several eyes

3. Start by Dividing into Two Large Parts

Begin by dividing the cluster into two large parts. Observe how the tubers have grown and are attached. Often, new tubers form during the growing season and are not as firmly attached to the original tuber. You may need to carefully untangle the tubers to avoid breaking them apart.

If the plant has two stems from the previous season, gently pry them apart, but with care. Otherwise, use a sharp knife or pruners. Be careful with the eyes and any visible shoots.

Did you know that Dahlia tubers are edible? If a large, fine tuber falls off during the process, why not try cooking it?

Bryt dahlian i två delar genom att ta tag i de gamla stjälkarna och bänd isär
Dela dahliaknölen med en sekatör

4. Now Divide into Smaller Parts

Now that you have two parts, it’s easier to see how the plant has grown. Continue dividing based on the size of the tuber. Remember, each part must have at least one tuber and one eye for shoots to develop. Label each tuber with a tag!

En hög med delade dahliaknölar
En färdigdelad dahliaknöl

5. An Alternative Method for More Dahlia Plants

Another method to get more Dahlia plants is to pre-grow a tuber in a large pot. Once the new shoots have grown, top them and plant the shoot as a cutting in a pot with soil.

If you buy Dahlia tubers and find nice large specimens, you can divide them too, following the advice in this post regarding eyes and tubers.

Pre-Grow Dahlias or Plant Directly Outdoors?

In our next post, we’ll go through how to create the best conditions for floral beauty all summer and well into autumn. Click to read about Planting Dahlias!

Document in Gardenize

Remember to note in Gardenize which Dahlia varieties you’ve divided, and how many tubers you’ve obtained, and make notes describing the process. This way, you’ll be ready to do the same next year or try something new.

Good luck with your Dahlias! Happy gardening!

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