Table of Contents
- Introduction
- When to Dig Your Dahlia Tubers
- How to Dig Dahlias Without Damage
- Cleaning and Drying the Tubers
- Dividing Dahlia Tubers: Now or Later?
- Step-by-Step: How to Divide
- The Importance of Labeling
- Choosing Your Storage Medium
- Packing Your Tubers for Winter
- Finding the Best Storage Location
- The Monthly Check-In
- Preparing for Spring
- Dealing with Common Storage Challenges
- Creating Your Own Storage System
- Summary of the Dahlia Storage Process
- Conclusion
- FAQ
Introduction
Dahlias are the undisputed stars of the late summer garden. Their vibrant colors and intricate shapes provide a sense of joy that few other flowers can match. As the growing season winds down, you may feel a strong desire to save those beautiful blooms for next year. While dahlias are tender perennials, they can easily be preserved with just a little bit of care and attention.
At Longfield Gardens, we want to help you enjoy your favorite varieties year after year, so browse our best-selling dahlias. Storing dahlia tubers is a rewarding way to expand your garden without starting from scratch each spring. This guide is designed for home gardeners who want a reliable, straightforward method for overwintering their tubers. We will walk through everything from the first frost to the final storage bin.
By following a few simple steps, you can ensure your dahlia collection remains healthy and ready to sprout when warm weather returns. Start with our dahlia collections. Proper winter storage is the bridge between this year's success and next year's beautiful display.
When to Dig Your Dahlia Tubers
The timing of your dahlia harvest is one of the most important factors for storage success. In most parts of the United States, dahlia tubers are dug up once the plants have finished their work for the year. This usually happens after the first "killing frost." If you're unsure about your climate, the Hardiness Zone Map can help.
A killing frost is easy to spot. Your once-vibrant dahlia plants will turn black or dark brown almost overnight. While it might look sad, this is actually a helpful signal from nature. This frost tells the plant to stop sending energy to the leaves and start focusing entirely on the tubers underground.
The Benefits of Waiting for Frost
Waiting for that first frost allows the tubers to reach full maturity. During the final weeks of autumn, the plant concentrates sugars and nutrients into the tubers. This process "hardens" the tubers, making them more resilient during their long winter nap. If you dig them too early, the tubers may be soft and prone to shriveling.
In warmer climates where a killing frost might not arrive until late December, you can still dig your tubers once the plants begin to yellow and die back naturally. Aim to have them out of the ground by mid-November to ensure they have enough time to rest before spring. For a broader overview of growing these flowers, read All About Dahlias.
The Short Wait Period
Many experienced gardeners prefer to wait about a week after the first frost before digging. After you cut the blackened stalks down to about four inches above the soil, the tubers remain in the ground for five to seven days. This brief waiting period can help the "eyes" of the tuber become more visible.
The eyes are small bumps or growth points located near the neck of the tuber. They are essential because a tuber without an eye will not produce a plant next year. Seeing them clearly makes the dividing process much easier later on.
What to do next:
- Monitor your local weather forecast for the first frost.
- Prepare your tools, including a garden fork and labeling materials.
- Once frost hits, cut the stalks down to 4 inches and wait 5–7 days.
How to Dig Dahlias Without Damage
Dahlia tubers are surprisingly fragile. They grow in a clump that resembles a bunch of sweet potatoes, and each individual tuber is connected to the main stem by a thin "neck." If this neck is bent or snapped, the tuber can no longer grow.
Because of this fragility, we recommend using a garden fork rather than a shovel. A fork allows you to loosen the soil without the risk of slicing through the tubers.
The Proper Digging Technique
Start by identifying the main stem of the plant. Instead of digging right next to the stem, move out about 12 inches in every direction. This creates a safety zone that protects the tubers from accidental hits.
Push the garden fork deep into the soil and gently pry upward. Work your way around the entire plant, loosening the earth from all sides. Once the soil is loose, you should be able to lift the entire clump from underneath.
Avoid the temptation to grab the "handle" of the remaining stem and pull. Pulling can easily snap the necks of the outer tubers. Instead, use your hands to lift the weight of the clump from the bottom while the fork supports it.
Initial Cleaning
Once the clump is out of the ground, gently shake it to remove large chunks of soil. Do not bang the tubers against each other or a hard surface, as this can cause bruising. At this stage, you just want to remove the bulk of the dirt so you can see what you are working with.
Cleaning and Drying the Tubers
After digging, the tubers need to be cleaned and dried before they go into storage. This step is vital for preventing rot and disease.
Washing vs. Brushing
There are two schools of thought on cleaning dahlias. Some gardeners prefer to wash them thoroughly with a garden hose. This makes it very easy to see the eyes and identify any soft spots or insect damage. If you have heavy clay soil, washing is often the only way to get them clean.
Other gardeners prefer to let the soil dry and then gently brush it off. This is a good option if you have very sandy soil. Brushing reduces the amount of moisture introduced to the tuber right before storage.
Whichever method you choose, the goal is to have clean, visible tubers. If you wash them, be sure to turn the clumps upside down. Dahlia stems are hollow, and water can easily get trapped inside. Turning them over allows the water to drain out, preventing "crown rot."
The Drying (Curing) Phase
Before packing them away, the tubers need to "cure" for a few days. Place them in a cool, dry area that is protected from direct sunlight and frost. A garage, shed, or covered porch usually works well.
Lay the clumps on a piece of cardboard, a wooden pallet, or a mesh screen. Avoid placing them directly on cold concrete, as concrete can pull moisture out of the tubers too quickly. Let them dry for two to three days until the skin feels firm and the cut ends of the stems have calloused over.
Key Takeaway: Properly curing your dahlia tubers for 2-3 days in a cool, dry spot is a simple step that significantly reduces the risk of rot during the winter months.
Dividing Dahlia Tubers: Now or Later?
One of the most common questions we hear is whether to divide dahlia clumps in the fall or wait until the spring. Both methods have advantages, and the right choice depends on your schedule and comfort level.
Dividing in the Fall
Many gardeners find it easier to divide tubers in the fall while the material is still relatively soft. As the tubers sit in storage, they can become quite hard and woody, making them more difficult to cut in the spring.
If you choose to divide now, you will save space. Individual tubers take up much less room than large clumps. However, the eyes can be harder to see in the fall. If you aren't sure where the eyes are, you might accidentally cut them off.
Waiting Until Spring
Waiting until spring is a safer bet for beginners. By the time April or May rolls around, the eyes will have begun to swell or even sprout. This makes it unmistakable where the growth point is. Storing the whole clump also provides a bit of a safety net; if one part of the clump develops rot, the rest might remain healthy.
The downside to waiting is that the clump will be much larger and more difficult to pack. You will also need more storage medium (like peat moss) to cover the entire mass.
Step-by-Step: How to Divide
If you decide to divide your tubers, you will need a sharp, clean pair of garden snips or a utility knife. It is a good idea to dip your tools in a solution of 10% bleach and water between each clump to prevent the spread of any soil-borne diseases.
- Examine the crown: Look for the "crown," which is the area where the tuber meets the main stem. This is where the eyes are located.
- Look for the eye: Find a small bump or "pimple" on the crown.
- Make the cut: Carefully cut a single tuber away from the main clump, ensuring that a piece of the crown (with at least one eye) remains attached to the tuber.
- Trim the ends: If the tuber is very long, you can trim off the bottom third. This doesn't hurt the plant and makes it easier to fit into storage containers.
- Remove the "Mother" tuber: The original tuber you planted in the spring is often large and dark. This "mother" tuber is more prone to rotting over the winter, so many gardeners choose to compost it and keep only the new, fresh tubers.
The Importance of Labeling
It is easy to think you will remember which variety is which, but by mid-January, every dahlia tuber looks remarkably similar. Labeling is the only way to ensure your garden design stays on track next year.
We recommend a multi-step approach to labeling. You can write the variety name directly on the skin of the tuber using a soft lead pencil or a permanent marker. This is a very reliable method because the label stays with the plant through the entire storage process.
Additionally, you can place the tubers in individual bags or use garden tags. If you are storing whole clumps, tie a waterproof tag to the stem. Clear communication with your future self will make spring planting much more enjoyable.
Choosing Your Storage Medium
Dahlia tubers need a environment that is "just right"—not too wet and not too dry. If the environment is too damp, they will rot. If it is too dry, they will shrivel up like raisins. To achieve this balance, we use a storage medium.
Popular Storage Materials
- Peat Moss: This is one of the most popular choices. It holds a small amount of moisture but is generally dry enough to prevent rot. It is also very lightweight.
- Vermiculite: This mineral is excellent for moisture regulation. It can absorb excess humidity while still providing enough moisture to keep the tubers firm.
- Wood Shavings: Pine or cedar shavings (the kind used for animal bedding) are affordable and provide great air circulation.
- Newspaper: Some gardeners wrap individual tubers in several layers of dry newspaper. This works well if your storage area has naturally high humidity.
At Longfield Gardens, we have found that a mix of slightly dampened peat moss or vermiculite often provides the most consistent results for home gardeners.
Packing Your Tubers for Winter
Once your tubers are clean, dry, and labeled, it is time to pack them away. You can use cardboard boxes, plastic bins, or even milk crates.
Using Plastic Bins
If you use plastic bins, do not snap the lid on tight. Tubers are living things and need to breathe. A tight lid will trap moisture and almost certainly lead to rot. Either leave the lid slightly ajar or drill several small holes in the sides of the bin to allow for air exchange.
The Layering Method
Start by placing a two-inch layer of your chosen storage medium at the bottom of the container. Arrange the tubers on top so they are not touching each other. This is important; if one tuber starts to rot, you don't want it to spread to its neighbors.
Cover that layer with more storage medium and repeat the process until the bin is full. Ensure the top layer is completely covered to protect the tubers from the air.
What to do next:
- Choose a container that fits your storage space (cardboard for damp areas, plastic for dry).
- Select a storage medium like peat moss or vermiculite.
- Pack tubers in layers, ensuring they do not touch one another.
Finding the Best Storage Location
The success of your overwintering depends heavily on the temperature of your storage spot. The ideal temperature range for dahlia tubers is between 40°F and 50°F.
Avoid the Freezing Point
If tubers freeze, they are finished. The water inside the tuber cells expands when it freezes, which turns the tuber into mush once it thaws. This means unheated sheds or detached garages are often too risky in cold northern climates unless you have a way to keep the temperature stable.
Avoid Too Much Heat
Conversely, if the storage area is too warm (above 55°F), the tubers may think it is time to grow. They will begin to sprout prematurely, which uses up the energy they need for the spring. Warm air also dries out the tubers much faster.
The "Goldilocks" Spots
- Basements: An unfinished, unheated basement is often the perfect spot. Stay away from the furnace or water heater.
- Crawlspaces: These usually maintain a very steady, cool temperature.
- Attached Garages: If your garage is attached to the house, the wall shared with the living space often provides just enough heat to keep the area above freezing.
The Monthly Check-In
Storing dahlias is not a "set it and forget it" task. We recommend checking on your tubers once a month throughout the winter. This simple habit can save your entire collection. If you're planning next year's display, take a look at our new dahlias.
What to Look For
Open your bins and feel a few tubers. They should feel firm, like a fresh potato. If they feel soft or slimy, they are beginning to rot. Immediately remove any rotten tubers and throw them in the trash (do not compost rotten tubers, as they can harbor pathogens).
If the tubers look shriveled and dry, the environment is too arid. You can lightly mist the storage medium with a spray bottle of water. You don't want it to be wet—just a tiny bit of moisture is enough to plump the tubers back up.
Adjusting the Environment
If you find a lot of condensation on the inside of your plastic bins, they need more air. Leave the lid off for a day to let the excess moisture evaporate, then drill more holes in the container before closing it back up.
Preparing for Spring
As the days grow longer and the ground begins to thaw, you can start thinking about planting. Most gardeners wait until the soil has warmed to about 60°F and all danger of frost has passed before putting dahlias back in the ground. For a planting refresher, see How Deep Should Dahlia Bulbs Be Planted?.
If you stored your tubers as whole clumps, this is the time to divide them. The eyes should be very prominent now, often showing green or purple sprouts. You can plant them directly into the garden or start them in pots indoors 4–6 weeks before the last frost to get a head start on the season.
Dealing with Common Storage Challenges
While the process is generally straightforward, nature sometimes throws a curveball. Understanding how to handle minor issues can keep your gardening journey positive.
Mold on the Surface
If you see a light dusting of white mold on the surface of your tubers, don't panic. This usually happens when the air is a bit too still or damp. Wipe the mold off with a cloth dipped in a very weak bleach solution and ensure the tubers have better air circulation moving forward.
Premature Sprouting
If your tubers start sending out long, pale sprouts in February, they are likely too warm. Move them to a cooler spot. You don't need to break the sprouts off; they are quite resilient. Just try to slow them down by lowering the temperature.
Broken Necks
During your monthly check, you might find a tuber that has a "floppy" neck. If the neck is broken, the tuber cannot send energy to the eye. Unfortunately, these tubers won't grow. It is best to discard them now so they don't take up space or potentially rot.
Creating Your Own Storage System
Every home is different, and you may need to experiment a little to find the perfect system for your microclimate. Some gardeners swear by plastic wrap, while others use sand. If you want a colorful next-season mix, browse the Dahlia Assorted Harvest Collection.
The "Simple Gardening Rules" suggest that you shouldn't be afraid to try one or two methods at the same time. If you have a large collection, try storing half in peat moss and half in wood shavings. This way, you can see which one performs best in your specific basement or garage. This observational approach is one of the best ways to become a more confident gardener.
Summary of the Dahlia Storage Process
Overwintering dahlias is a cycle that connects one beautiful summer to the next, and the Dahlia Assorted Sangria Collection is a colorful example of what’s waiting next season. It begins with the first frost and ends with the first warm spring breeze.
- Wait for the sign: Let the frost turn the foliage black to ensure the tubers are mature.
- Dig with care: Use a fork and stay 12 inches away from the stem to protect the fragile necks.
- Clean and cure: Remove the soil and let the tubers dry for 2–3 days in a protected area.
- Pack thoughtfully: Use a medium like peat moss or vermiculite and ensure tubers aren't touching.
- Monitor: Check your tubers monthly to manage moisture and remove any rot.
Conclusion
At Longfield Gardens, we believe that every gardener can achieve success with the right support, and our About Us page explains how we stand behind your garden. We hope this guide makes the process feel accessible and rewarding. Whether you are saving a single sentimental variety or a whole field of color, the effort you put in now will be rewarded with a spectacular show next summer. When you are ready to browse again, explore the Dahlia Assorted Sunlit Jewel Collection.
"The care you give your tubers during the winter is the secret to a head start on a breathtaking summer garden."
We look forward to seeing your dahlias bloom again soon. For more tips on planting and care, feel free to explore our other gardening guides, and review our Shipping Information.
FAQ
How do I know if a dahlia tuber is dead or rotten?
A healthy tuber should feel firm to the touch, similar to a potato. If a tuber is squishy, slimy, or smells unpleasant, it has likely succumbed to rot and should be discarded. If a tuber is extremely light and brittle, it may have dried out completely and is unlikely to grow. For broader help, see our FAQs - General Bulbs and Plants.
Can I store dahlia tubers in the refrigerator?
While a refrigerator maintains a cool temperature, it is often too dry and cold (near 35°F) for long-term dahlia storage. Additionally, many refrigerators contain ripening fruit that releases ethylene gas, which can damage or kill the tubers. A cool basement or crawlspace is a much better option.
What happens if I don't dig up my dahlias in the winter?
In USDA hardiness zones 8 and warmer, dahlias can often stay in the ground if the soil doesn't freeze deeply. However, in zones 7 and colder, the freezing ground will kill the tubers. If you live in a cold climate and leave them in the ground, they will turn to mush and will not return in the spring.
Do I need to wash the tubers before storing them?
Washing is not strictly necessary, but it can be very helpful. It allows you to see the "eyes" more clearly and ensures you aren't bringing soil-borne pests or excess moisture-holding clay into your storage bins. If you do wash them, just ensure they are dried thoroughly before being packed away.