Overwintering Dahlia Tubers in the Ground: Our Experience in Zone 6, Southwest Michigan
One of the biggest roadblocks to growing dahlias is winter storage. For years, I avoided growing them simply because I didn’t have the typical storage space—no basement, no ideal cool, dark place to keep them over winter. But after researching alternative methods, I discovered that overwintering dahlias in the ground could be a viable solution.
The Traditional Method of Storing Dahlia Tubers
Most dahlia growers follow the standard practice of digging up tubers in the fall, cleaning and dividing them, and storing them indoors in peat moss, vermiculite, or plastic wrap. This method protects the tubers from freezing temperatures and rot, ensuring they survive until spring. However, for those of us without dedicated storage space, this process can be daunting—if not impossible.
Exploring In-Ground Overwintering
Since I lacked an indoor storage option, I began researching leaving dahlia tubers in the ground through winter. One of the best resources I found was Jenny Love of Love 'n Fresh Flowers, whose blog provided valuable insights into how this method could work. I took her recommendations, adapted them to our conditions, and conducted a small test trial.
In the first year, I overwintered a few small rows, and to my surprise, I had great success! Given our sandy, well-draining soil, the tubers survived the winter without rotting. In the spring, I dug them up, divided them, and either replanted or sold them. Initially, my plan was to leave them in the same place, but as things evolved, I decided to move them to a new growing area—something I will also be doing this year.
Our Overwintering Process
If you're considering overwintering dahlias in the ground, here’s the process that has worked best for us:
Cut Back the Plants – At the end of the season, I cut the stalks down to the ground and discard the plant material (composting or disposing of it as needed). You don’t have to wait for the first frost—I do it whenever I have time, sometimes before frost, sometimes after.
Apply a Thick Layer of Mulch – Since we have an abundance of leaves, I mulch about 12 inches of shredded leaves over the rows and in the paths between them. This thick layer provides insulation and helps regulate soil temperature.
Cover with Tarps – To further protect the tubers, I cover the entire area with a tarp. The first few years, I used a regular tarp because that’s what I had on hand, but they eventually broke down. Last year, I switched to used billboard tarps, which are much more durable. These tarps are heavy, so I cut them in half to make them more manageable.
Secure the Tarps – To keep the tarps in place through winter, I use T-posts around the edges and in any overlapping sections in the middle. Once everything is secured, I leave it in place until spring.
Spring Uncovering & Next Steps
The timing of removing the tarps varies depending on the weather, but I typically do it around mid-April, once we’re past snow and the ground isn’t frozen. At this point, you have a few options:
Leave the plants as they are – Dahlia clumps can grow well undisturbed.
Dig and move the clumps – If you want to change your garden layout, you can relocate them.
Dig, divide, and replant – This keeps your plants manageable and ensures strong growth.
Keep in mind that if you leave dahlias in the ground for multiple years, the clumps will become very large and difficult to handle. It’s best to lift and divide them every few years to maintain manageable growth and ensure continued vigor.
Final Thoughts
This method may take some experimenting to perfect for your location, but if you’re in Zone 6 with well-draining soil and limited storage space, I encourage you to give it a try! Overwintering dahlias in the ground has allowed us to continue growing these beautiful flowers without the hassle of indoor storage.
Have you tried this method? I’d love to hear about your experience! Drop a comment or reach out on Facebook or Instagram to share your results.
