Maximizing Dahlia Growth: Propagation Tips for Intact Tuber Clumps

Copyright © 2025 by Steve K. Lloyd

As an avid dahlia grower , I always face a decision in late winter: should I divide tubers for direct planting or use them to take cuttings? I recently read a scientific article that sheds light on how intact dahlia tuber clumps—rather than divided tubers—can be used to produce vigorous cuttings.

This method, widely practiced in Great Britain, contrasts with the American tradition of dividing tubers in fall, offering intriguing alternatives for propagation.

Here’s a breakdown of the study and its practical applications for dahlia growers.

The study, conducted from 2011 to 2014 at the University of Life Sciences Felin Experimental Farm in Lublin, Poland, explored the productivity of intact dahlia tuber clumps for producing soft cuttings. Researchers used intact clumps from four cultivars: Krynica, Balbinka, Celinka, and Halinka. 

Although these particular dahlia varieties are not widely available in the United States, the specific dahlias used in the study are not as important as what the researchers discovered.

Each dahlia used in the study consisted of a clump with three to four tubers weighing 120–200 grams (4–7 ounces), providing a robust base for sprouting with multiple eyes in each clump.

The term “intact tuber clump” refers to the whole, undivided root mass from which new shoots emerge. This approach takes advantage of the entire growth zone of the clump, allowing multiple shoots to sprout for cutting, rather than limiting propagation to individual tubers.

Four cutting methods were compared to evaluate rooting success and plant vigor:

• Apical Cuttings with a Heel : A portion of the tuber clump was left attached to the cutting, providing additional nutrients.
  
  

• Apical Cuttings without a Heel : Shoots were snipped above the clump, preserving the eye for future growth.
  
  

• Two-Node Cuttings : Included two leaf nodes but no heel.
  
  

• Leaf-Bud Two-Node Cuttings : Focused on a single node and accompanying leaf.

1. Efficiency of Intact Tuber Clumps
   Intact tuber clumps proved highly productive, generating 60–102 cuttings per clump, depending on the cultivar and growing conditions. Krynica and Halinka were the most prolific varieties.
   
   

2. Rooting Success
   Cuttings with a heel had the highest rooting rates (92–100%), likely due to the extra nutrients and growth hormones provided by the attached tuber tissue.
   
   

3. Cutting Quality
   Heel cuttings developed the strongest root systems and had the highest fresh weights, making them ideal for establishing vigorous plants.

This freshly-dug dahlia tuber clump will be stored intact and used for taking spring cuttings.

Leaving tubers intact over winter allows growers to maximize the number of cuttings from each plant. Unlike divided tubers, which limit propagation to the number of viable eyes, intact clumps can continue producing new shoots throughout the season.

While heel cuttings produced the strongest roots, other methods—such as apical and two-node cuttings—still delivered high rooting success. Growers can experiment with these types to balance plant vigor and the number of cuttings obtained from each clump.

• For Maximum Cuttings : Preserve the intact clump by using apical or two-node cuttings, which leave the eye intact for additional growth.
  
  

• For Strong Plants : Opt for heel cuttings if the goal is fewer but more vigorous plants.

For growers used to dividing dahlia tubers in autumn, this study suggests a potential shift in practice. By storing intact clumps over winter, you can preserve the productive base and harvest multiple cuttings in spring. This approach offers advantages, particularly for growers looking to maximize their plant yield or experiment with propagation techniques.

A common question among growers is whether taking cuttings from intact clumps is more efficient than simply dividing tubers.

• Dividing Tubers : Produces one plant per eye, a straightforward method with minimal labor.
  
  

• Taking Cuttings : Allows for multiple plants from the same tuber clump, especially when using methods that preserve the eyes for continued sprouting.

Potted dahlia cuttings ready for transplant into the garden.

This Polish study highlights the benefits of using intact dahlia tuber clumps for propagation. By experimenting with cutting types and leveraging the productive capacity of these clumps, growers can enhance their practices, whether for home gardens or commercial operations.

As for me, I stored several dahlia varieties as intact clumps last winter, rather than dividing them as usual. I’m excited to compare the results and see how this method influences the number and quality of cuttings I can take this spring.

The Efficiency of Mother Crowns and Quality of Soft Cuttings of a Few Dahlia Cultivars (Lublin University Study).

This article was written with the help of AI (ChatGPT) to organize research and summarize key findings from scientific sources. While I carefully reviewed the content to ensure that all statements are backed by specific research papers, I rely on AI’s interpretation of the technical material. This is a collaborative effort—AI helps with analysis and structure, while I make sure everything aligns with the intended discussion.