How to Store Dahlia Tubers for the Winter

Table of Contents

1. Introduction
2. Knowing When to Dig Your Dahlias
3. Preparing for the Dig: Tools and Strategy
4. Step-by-Step Guide to Lifting Dahlia Tubers
5. Cleaning and Curing Your Tubers
6. Dividing Dahlia Tubers: Fall vs. Spring
7. Choosing the Best Storage Medium
8. Ideal Conditions for Winter Dormancy
9. Monitoring Your Tubers During Winter
10. Troubleshooting Common Storage Issues
11. Conclusion
12. FAQ

Introduction

There is a unique kind of joy that comes from watching a dahlia garden reach its peak in late summer. Those massive Dinnerplate Dahlias and intricate pompons offer a spectacular finale to the growing season. At Longfield Gardens, we know that once you fall in love with a specific variety, you want to see it return to your garden year after year, and Dahlia Collections make that easier.

Because dahlias are native to the warm climates of Mexico and Central America, they cannot survive freezing temperatures in most parts of the United States. While some gardeners in very warm zones can leave them in the ground, most of us need to lift and protect them. This process, often called "overwintering," is a rewarding way to build your collection and ensure your favorite plants stay healthy.

This guide is designed for any gardener who wants a reliable, step-by-step method for preserving their dahlias. We will cover how to recognize the right time to dig, how to clean and cure the tubers, and which storage methods offer the best results. By following a few simple steps, you can keep your tubers dormant and healthy until it is time to plant again in the spring.

Storing dahlia tubers is a straightforward process that rewards a little bit of autumn effort with a lifetime of beautiful summer blooms.

Knowing When to Dig Your Dahlias

Timing is one of the most important factors when it's time to store dahlia tubers for the winter. If you dig too early, the tubers may not have stored enough energy to sprout the following year. If you wait too long, a deep freeze could damage the tuberous roots. The goal is to allow the plant to finish its natural cycle so the tubers are mature and "cured" by the time they go into storage.

The Role of the First Frost

For most gardeners, the signal to start digging is the first frost. A light frost will usually turn the dahlia’s foliage from a vibrant green to a dark brown or black. While it might look a bit sad to see your plants wilt, this is actually a beneficial part of the process. When the foliage dies back, the plant sends a final burst of energy down into the tubers, thickening their skins and preparing them for dormancy.

After the foliage has turned black, we recommend waiting about five to seven days before digging. This short waiting period allows the "eyes" (the small buds that will become next year's stems) to become more prominent, which makes dividing the clumps much easier later on. However, if your soil is exceptionally wet or if a hard, deep freeze is expected, you should proceed with digging sooner to avoid rot.

Regional Variations

Your specific location and USDA hardiness zone will dictate your timeline. In northern states, you may be digging in late September or October. In more temperate regions, you might wait until November. If you live in a region where the ground never freezes (typically Zone 8 or warmer), you might choose to leave your dahlias in the ground. However, even in warm climates, many gardeners prefer to lift their tubers every couple of years to divide them and refresh the soil. If you need help, our Hardiness Zone Map can help you find your zone.

Key Takeaway: Wait for the first frost to blacken the foliage, then give the tubers a few days in the ground to toughen their skins before you begin the lifting process.

Preparing for the Dig: Tools and Strategy

Before you head out to the garden, gathering the right tools will make the job much faster and safer for the plants. Dahlia tubers are surprisingly fragile, especially at the "neck"—the thin area where the tuber connects to the main clump. If the neck is broken or severely creased, the tuber usually won't be able to grow a new sprout in the spring.

Recommended Tools

• Garden Fork: This is the most important tool for the job. A sturdy garden fork (sometimes called a digging fork) is much better than a shovel. The tines allow you to lift the soil and the tuber clump together without the risk of slicing through the tubers.
• Pruners or Loppers: You will need these to cut back the heavy stalks.
• Garden Hose: A hose with a spray nozzle is essential for cleaning the soil off the clumps so you can inspect them for health.
• Labeling Supplies: Waterproof tags or a permanent marker are vital. Once the tubers are out of the ground, they all look very similar. You’ll want to know which is your favorite Cafe Au Lait and which is a bright yellow variety.
• Sterilizing Solution: A simple mix of one part bleach to ten parts water helps keep your tools clean. We suggest wiping your blades between different plants to prevent the spread of any potential soil-borne issues.

Labeling Before You Dig

It is much easier to identify your dahlias while they still have flowers or at least recognizable foliage. If you haven't already labeled your plants, do it now while you can still tell them apart. You can tie a tag directly to the base of the stalk. This simple step saves a lot of guesswork in the spring when you are trying to plan your garden layout.

Step-by-Step Guide to Lifting Dahlia Tubers

Lifting the tubers requires a gentle touch and a bit of patience. Think of the tuber clump as a delicate subterranean structure that needs to be supported from all sides.

Cutting Back the Foliage

Start by cutting the stalks down to about four to six inches above the ground. Leaving a bit of the stem acts as a handle, making it easier to maneuver the clump. Be careful not to pull on these stems too hard, as you don't want to stress the connection point between the stem and the tubers. Some gardeners like to cover the hollow stems with a bit of aluminum foil if rain is expected before they dig, which keeps water from sitting in the crown and encouraging rot.

The Lifting Technique

1. Start Wide: Place your garden fork about 10 to 12 inches away from the center of the plant. Dahlias can grow surprisingly wide, and you want to avoid hitting the tubers with the tines.
2. Loosen the Soil: Gently push the fork into the ground and rock it back and forth. Do this on all four sides of the plant to loosen the root system.
3. Lift Gently: Once the soil is loose, slide the fork deep under the clump and use a prying motion to lift the entire mass upward.
4. Remove Excess Soil: Use your hands to gently shake off the largest clumps of dirt. At this stage, the tubers are still very hydrated and the skins are soft, so handle them like you would handle a carton of eggs.

What to do next:

• Cut stems to 4–6 inches.
• Label each clump immediately.
• Dig a wide circle around the plant with a garden fork.
• Lift the clump from underneath to protect the "necks."
• Gently shake off loose soil.

Cleaning and Curing Your Tubers

Once the tubers are out of the ground, they need to be cleaned and "cured." Curing is simply a process of letting the tubers dry slightly so the outer skin can toughen up, which acts as a protective barrier against rot and dehydration during the winter months.

Washing the Clumps

Using a garden hose, wash away the remaining soil. It is important to see the individual tubers clearly so you can inspect them for any signs of damage or decay. Washing also removes soil-borne insects or pathogens that you don't want to bring into your storage area.

If you have heavy clay soil, you might need to use your fingers to gently nudge the dirt out from the center of the clump. Be thorough but gentle. Once they are clean, turn the clumps upside down (stems pointing toward the ground) to allow any water trapped in the hollow stems to drain out. For a deeper look at tuber anatomy, see Dahlia Tubers: What You Need to Know.

The Curing Process

Move your clean tubers to a protected area that is out of direct sunlight but has good air circulation. A garage, a shed, or a covered porch works well. Avoid areas that are too cold (below 40°F) or too hot.

Let the tubers sit for one to three days. During this time, the skin will lose its translucent look and become slightly leathery. This is a good thing! If you see the tubers starting to shrivel or look like raisins, they have been out too long and need to be packed away immediately. The goal is "dry to the touch" but still firm and plump inside.

Dividing Dahlia Tubers: Fall vs. Spring

One of the most common questions gardeners ask is whether to divide the tubers in the fall or wait until the spring. Both methods have advantages, and the "right" choice often depends on your personal schedule and how much storage space you have.

Dividing in the Fall

Many gardeners prefer to divide their dahlias in the autumn right after cleaning. The tubers are softer and easier to cut at this time. Dividing now also takes up significantly less storage space, as you are storing individual tubers rather than large, bulky clumps.

When dividing in the fall, you must ensure that each individual tuber has a piece of the "crown" (the area where the tuber meets the stem) and at least one "eye." The eye is a small, often invisible bump that will sprout into next year’s plant. Since eyes can be hard to see in the fall, some gardeners find this method a bit like a guessing game.

Waiting Until Spring

If you are a beginner, waiting until spring is often the safer bet. During the winter, the "eyes" will often start to swell or even sprout slightly, making them very easy to identify. If you store the clumps whole, you don't have to worry about whether each piece has an eye until you are ready to plant. The only downside is that the clumps are much harder and "woody" in the spring, so you will need a very sharp knife and a bit more hand strength to separate them.

Regardless of when you divide, always use a clean, sharp knife. Discard any tubers that feel mushy, look hollow, or show signs of mold. A healthy tuber should feel firm, similar to a fresh potato. For more growing basics, see 8 Tips for Growing Better Dahlias.

Key Takeaway: If you have limited space, divide in the fall. If you want to ensure you don't miss the "eyes," store the clumps whole and divide them in the spring.

Choosing the Best Storage Medium

The biggest challenge in storing dahlia tubers is finding the balance between keeping them dry enough to prevent rot and moist enough to prevent shriveling. The "storage medium" is the material you pack around the tubers to help maintain this balance.

Popular Storage Materials

• Wood Shavings: Pine or cedar shavings (the kind sold for animal bedding) are excellent. They provide good insulation and allow for some air movement while absorbing excess moisture.
• Vermiculite: This is a mineral that holds moisture very well. It is a favorite for many dahlia enthusiasts because it helps keep the tubers hydrated without being "wet."
• Peat Moss: This is a classic choice. It is naturally slightly acidic, which can help inhibit fungal growth. Ensure the peat moss is only very slightly damp—if you squeeze it, no water should come out.
• Perlite: Similar to vermiculite, perlite is clean and provides good aeration, though it doesn't hold moisture quite as effectively as vermiculite.

The Plastic Wrap Method

In recent years, many gardeners have had success with the "Saran Wrap" or plastic wrap method. After curing and dividing the tubers, you wrap each individual tuber tightly in plastic wrap, ensuring no air is trapped inside. This method uses the tuber's own moisture to keep it plump. It takes more time upfront but can be very successful if you are only storing a few dozen tubers.

Containers

You can store your packed tubers in cardboard boxes, plastic bins, or milk crates. Cardboard boxes are great because they "breathe," but they can get soggy if the storage area is damp. Plastic bins hold moisture well, which is good for preventing shriveling, but you must leave the lid slightly ajar or drill small holes in the sides to prevent condensation and rot.

Ideal Conditions for Winter Dormancy

Where you put your tubers is just as important as how you pack them. They need a "Goldilocks" environment: not too hot, not too cold, and just right in terms of humidity.

Temperature

The ideal temperature for dahlia storage is between 40°F and 50°F (4°C to 10°C). If the temperature stays consistently above 55°F, the tubers may think it's spring and try to sprout prematurely. If the temperature drops below freezing (32°F), the water inside the tubers will freeze, causing the cells to burst and the tuber to turn into a mushy, black mess.

Unheated basements, crawl spaces, or insulated garages are usually the best spots. Avoid placing them near furnaces, water heaters, or on cold concrete floors. If you store them in a garage, keep the boxes off the floor by placing them on a shelf or a wooden pallet. If you want a step-by-step refresher on winter care, read How to Store My Dahlia Bulbs.

Humidity

Dahlias prefer a relatively humid environment (around 70–80% humidity) to stay plump. However, in most homes, the air is very dry during the winter. This is why the packing material is so important. If your storage area is very dry, you may need to check your tubers more frequently to make sure they aren't shriveling.

Monitoring Your Tubers During Winter

Overwintering dahlias isn't a "set it and forget it" task. We recommend checking on your tubers once a month throughout the winter. This allows you to catch small problems before they spread to your entire collection.

What to Look For

When you do your monthly check, look for two things: rot and shriveling.

• If you see rot: If a tuber feels soft, mushy, or has fuzzy mold growing on it, remove it immediately. If the rot is only on a small part of a large clump, you can sometimes cut away the bad part with a sterile knife, let the cut surface dry, and put the rest back into storage.
• If you see shriveling: If the tubers are starting to look wrinkled or feel light and hollow, they are losing too much moisture. You can lightly mist the storage medium with a spray bottle of water. Do not soak it—just a tiny bit of moisture is usually enough to stop the shriveling.

Staying Positive

Don't be discouraged if you lose a few tubers during the winter. Even professional growers expect a small percentage of loss. By checking them regularly, you ensure that the vast majority of your dahlias will make it through to spring. Every year you do this, you will get a better "feel" for your specific storage environment.

Troubleshooting Common Storage Issues

Most problems with dahlia storage come down to moisture management. By focusing on the basics of temperature and airflow, you can solve most issues before they start. For a broader overview of dahlia types and care, see All About Dahlias.

Preventing Mold and Rot

Rot is almost always caused by too much moisture or poor airflow. If you find that your tubers are consistently rotting, try a more breathable storage medium like wood shavings, or switch from a plastic bin to a cardboard box. Also, ensure you are cleaning the tubers thoroughly; leftover soil can harbor the fungi that cause rot.

Dealing with Pests

Occasionally, mice or other small rodents might find your dahlia tubers to be a tasty winter snack. If you have a known rodent problem in your storage area, consider using heavy-duty plastic bins with small air holes drilled in them, or place your boxes in an area where pests can't reach them.

Premature Sprouting

If your tubers start sending out long, white sprouts in February or March, they are likely too warm. Move them to a cooler spot if possible. If the sprouts are small, don't worry—you can leave them alone, or if they get very long and spindly, you can simply snap them off when you are ready to plant in the spring. A new sprout will grow from the eye once the tuber is placed in warm soil.

Conclusion

Successfully storing dahlia tubers for the winter is one of the most rewarding skills a gardener can learn. It allows you to preserve the specific colors and forms that make your garden feel like home, especially in favorite collections like the Dahlia Dinnerplate Cloud Nine Collection.

At Longfield Gardens, we believe that gardening should be an enjoyable journey of discovery. While it takes a little bit of effort to tuck your dahlias away for the winter, the excitement of seeing those first green shoots emerge in the spring makes it all worthwhile. If you like rich, seasonal color, the Dahlia Dinnerplate Summer Lovin Collection is another place to start planning.

• Wait for the frost to signal the start of dormancy.
• Handle with care, especially the fragile "necks" of the tubers.
• Maintain the balance between too wet and too dry in your storage area.
• Check monthly to ensure your collection stays healthy.

The extra care you provide in the autumn is exactly what allows your garden to reach its full potential in the heat of July and August.

We look forward to helping you grow a more beautiful garden, one season at a time. With your tubers tucked away safely, you can spend the winter months dreaming of the vibrant colors and stunning blooms that will fill your yard next year, or plan ahead with the Dahlia Dinnerplate High Summer Mix - Bulk Offer.

FAQ

Do I have to wash the dirt off the tubers before storing them?

While some gardeners have success with "dry brushing" the soil off, we recommend washing them. Washing allows you to see the "eyes" and the crown more clearly, which is essential for identifying rot or damage. It also removes pests and soil-borne diseases that could thrive in a dark, humid storage container.

What is the best temperature for storing dahlia tubers?

The "sweet spot" for dahlia storage is between 40°F and 50°F. If it gets colder than 32°F, the tubers will freeze and die. If it stays warmer than 55°F, they may shrivel or begin to grow before you are ready to plant them in the spring.

My tubers are shriveling in storage. Can I save them?

Yes, shriveling is a sign that the environment is too dry. You can usually revive them by lightly misting the storage medium (like the wood shavings or peat moss) with a spray bottle of water. Avoid soaking them, as this can lead to rot; a small increase in humidity is usually all they need to plump back up.

Can I store dahlias in the refrigerator?

While a refrigerator provides the correct temperature, it is often too dry for dahlia tubers and can lead to severe shriveling. Additionally, storing tubers near certain fruits (like apples) can be harmful because the ethylene gas produced by the fruit can damage the tubers' ability to sprout. An unheated basement or insulated garage is usually a much better choice.