What Do I Store Dahlia Tubers In?

Table of Contents

1. Introduction
2. Choosing the Right Container for Your Environment
3. The Best Packing Materials (Storage Mediums)
4. Preparing Tubers for Their Container
5. Step-by-Step Packing Guide
6. The Ideal Storage Environment
7. Mid-Winter Maintenance
8. Summary of Storage Scenarios
9. Conclusion
10. FAQ

Introduction

There is a unique sense of accomplishment that comes with a garden full of dahlias. From the dinnerplate dahlias to the intricate petals of pompon varieties, these plants are the undisputed stars of the late-summer landscape. As the growing season winds down, many gardeners find themselves wanting to save that beauty for next year. While dahlias are tender perennials that cannot survive freezing ground temperatures, saving their tubers is a simple and rewarding process.

At Longfield Gardens, we believe that every gardener can successfully overwinter their favorite varieties with just a little preparation. If you want to compare more dramatic forms, browse our Big Blooms. Storing tubers is not about following a single, rigid rule. Instead, it is about finding the right container and packing material that fits your specific home environment. Whether you have a chilly basement, a dedicated garden shed, or a cool crawl space, there is a storage method that will work for you.

This guide will focus on the most effective containers and materials to keep your dahlias healthy during their winter nap. To compare shapes and colors for next season, explore our dahlia collections. We will cover the pros and cons of different storage vessels and the best "stuffing" to use to prevent shriveling or rot. Our goal is to help you feel confident as you tuck your tubers away, ensuring they are ready to burst back into life when spring returns.

Proper storage is the bridge between one beautiful season and the next.

Choosing the Right Container for Your Environment

The most common question gardeners ask after digging up their dahlias is whether they should use plastic, cardboard, or wood. The answer depends almost entirely on the humidity levels in your chosen storage area. Dahlia tubers need a environment that is "just right"—not so dry that they shrivel up like raisins, and not so wet that they turn to mush.

When choosing a container, think about the airflow in your storage space. If you are storing tubers in a modern basement with a furnace, the air will likely be very dry. If you are using an unheated garage or a root cellar, the air might be quite damp. Your container should act as a buffer against these conditions.

Plastic Storage Bins

Plastic bins are a popular choice because they are inexpensive, stackable, and excellent at retaining moisture. They are particularly useful if your storage area is very dry. However, because plastic does not "breathe," you must be careful about trapped moisture.

If you choose plastic bins, it is often helpful to drill a few small ventilation holes in the sides. This allows a tiny amount of air exchange, which prevents condensation from forming on the inside of the lid. If you see water droplets on the lid during your winter checks, it is a sign that the tubers need more air.

Cardboard Boxes

Cardboard is a classic choice for dahlia storage. It is naturally breathable and can absorb a small amount of excess moisture if the tubers are slightly damp. Cardboard boxes work well in environments with moderate humidity.

The main drawback to cardboard is that it offers less protection against rodents. If your storage area is a shed or a garage where mice might visit, you may want to place the cardboard boxes inside a larger, ventilated plastic crate or a wire mesh enclosure.

Paper Bags

For gardeners with smaller collections or those who prefer to keep varieties separate, heavy-duty paper bags are an excellent option. If you like to sort by bloom form, see our pompon dahlias. They provide good breathability and make it easy to label each bag with the variety name. Many gardeners place several individual paper bags into a larger wooden crate or cardboard box to keep things organized.

Wooden or Plastic Crates

Open-style crates, such as old milk crates or bulb crates, provide the maximum amount of airflow. These are ideal for environments that are naturally very humid (around 80% to 90% humidity). Because the tubers are more exposed in a crate, you will need to rely more heavily on your packing medium to keep them from drying out.

Key Takeaway: Choose plastic bins for dry storage areas to keep moisture in, and use cardboard or open crates for damp areas to prevent rot through better airflow.

The Best Packing Materials (Storage Mediums)

Once you have selected your container, you need a material to surround the tubers. Before you pack your dahlia tubers, this material, often called a storage medium, serves two main purposes: it insulates the tubers against temperature swings and regulates the humidity immediately surrounding the tuber clumps.

Peat Moss

Peat moss is perhaps the most traditional material used for storing dahlias. It is lightweight, relatively inexpensive, and holds moisture exceptionally well. It also has a slightly acidic pH, which some gardeners believe helps inhibit the growth of fungus and rot.

When using peat moss, it should be "lily-pad damp"—meaning it feels slightly cool to the touch but does not release any water when you squeeze it. If the peat moss is bone-dry, it will actually pull moisture out of your tubers, causing them to shrivel.

Vermiculite

Vermiculite is a mica-like mineral that has been heated until it expands into light, absorbent flakes. It is a favorite among many dahlia enthusiasts because it is sterile and excellent at regulating moisture. It can absorb excess water if the tubers are too wet and release it if the environment gets too dry.

While vermiculite can be more expensive than other options, it can often be reused for several years if it is kept clean and dry between seasons. It is particularly helpful for storing individual tubers that have already been divided.

Pine Shavings

The large wood shavings often sold as animal bedding (especially for horses or rabbits) are an excellent, low-cost storage medium. They provide good insulation and allow for plenty of air pockets around the tubers. Avoid using fine sawdust, as it can pack too tightly and hold too much moisture against the skin of the tuber, which may lead to rot.

Perlite

Similar to vermiculite, perlite is a volcanic glass that helps with aeration. However, perlite does not hold moisture as well as vermiculite or peat moss. It is best used in very humid storage areas where the primary goal is to keep the tubers separated and allow air to circulate.

Newspaper or Brown Paper

If you don't have access to loose materials, wrapping individual tubers or small clumps in several layers of newspaper can work. The paper provides a small buffer against temperature changes and prevents the tubers from touching one another. This is often called the "dry wrap" method and is best suited for environments with very consistent, moderate humidity.

Comparison of Storage Mediums

Material	Best For	Moisture Retention	Airflow
Peat Moss	Dry environments	High	Moderate
Vermiculite	Precision moisture control	High	High
Pine Shavings	Budget-friendly storage	Moderate	High
Paper/News	Small collections	Low	Moderate

Preparing Tubers for Their Container

Before you place your dahlias in any container, they need a little bit of "spa treatment" to ensure they are ready for dormancy. Putting wet or dirty tubers directly into a sealed container is a recipe for trouble.

Cleaning and Inspection

After digging, we recommend gently brushing off the large clumps of soil. Some gardeners prefer to wash their tubers with a hose to see the "eyes" (the small bumps where next year’s growth will emerge) more clearly. If you do wash them, it is vital that they dry completely before going into storage.

Inspect each clump for signs of damage or soft spots. If a tuber feels squishy or looks dark and rotten, it is best to remove it now. Healthy tubers should feel firm, similar to a fresh potato.

The Drying (Curing) Phase

Once cleaned, let the tubers sit in a cool, dry place out of direct sunlight for about 24 to 48 hours. This allows the outer skin to toughen up slightly, a process known as curing. Curing helps the tuber retain its internal moisture throughout the winter.

Do not leave them out for too long, especially in a breezy area, or they will begin to shrivel. As soon as the surface is dry to the touch and the soil has turned to dust, they are ready for their packing material.

To Divide or Not to Divide?

You can store dahlias as whole clumps or as individual divided tubers. For gardeners who want a simpler shopping list next spring, single dahlias are easy to plan around.

• Storing Clumps: This is the easiest method. It takes up more space, but the tubers are less likely to dry out because they are still attached to the main stem.
• Storing Divisions: This saves a significant amount of space. However, because divided tubers have more "cut" surfaces, they are more vulnerable to drying out. Many gardeners wait until spring to divide their clumps when the eyes are easier to see.

What to do next:

• Clear a workspace in a garage or shed.
• Gather your containers and chosen storage medium.
• Clean and dry your tubers for at least 24 hours.
• Label each variety with a waterproof marker or tag.

Step-by-Step Packing Guide

Once your tubers are dry and your materials are ready, follow these steps to pack your containers for the winter.

1. Create a Base Layer

Start by placing a 2- to 3-inch layer of your chosen storage medium (peat moss, vermiculite, or shavings) at the bottom of the container. This layer acts as a cushion and a moisture reservoir.

2. Arrange the Tubers

Place your tubers or clumps onto the base layer. The most important rule here is to make sure they are not touching each other. If one tuber develops rot, keeping them separated prevents the problem from spreading to the entire batch. If you are storing whole clumps, you can place them upside down to ensure any moisture trapped in the hollow stems drains out.

3. Cover and Repeat

Pour more storage medium over the tubers until they are completely covered. If your container is deep enough, you can add another layer of tubers on top, followed by more medium. Always finish with a final 2-inch layer of material on top to seal out the air.

4. Labeling is Key

It is easy to think you will remember which tuber is which, but by April, most dahlia tubers look identical. Label the outside of the container clearly. Many gardeners also use a soft pencil or waterproof marker to write the variety name directly on the skin of the tuber.

5. Secure the Lid (Carefully)

If using a plastic bin, place the lid on loosely or ensure your ventilation holes are clear. If using cardboard, you can fold the flaps shut. Place the containers in their winter home.

The Ideal Storage Environment

No matter what container you use, the success of your overwintering depends on the room where those containers sit. At Longfield Gardens, we have found that the "Goldilocks" temperature for dahlia storage is between 40°F and 50°F. If you want to check how that fits your region, use our Hardiness Zone Map.

Temperature Consistency

If the temperature drops below 32°F, the water inside the tubers will freeze, causing the cell walls to burst. When they thaw, they will be mushy and dead. Conversely, if the temperature stays above 55°F for too long, the tubers may think it is spring and try to sprout prematurely, exhausting their energy reserves.

Humidity Levels

The ideal humidity for dahlia storage is around 75% to 85%. This is quite damp compared to the air inside a heated home. This is why we use storage mediums like peat moss—they create a micro-climate of high humidity right around the tuber, even if the room itself is a bit drier.

Common Storage Locations

• Unheated Basements: Often the best choice, especially in older homes. Stay away from the furnace or water heater.
• Attached Garages: Can work well, but you must ensure the temperature doesn't drop below freezing during a cold snap. Placing containers on a shelf rather than the cold concrete floor can help.
• Crawl Spaces: Usually have excellent temperature and humidity, but can be difficult to access for monthly checks.
• Root Cellars: The gold standard for tuber storage, providing naturally cool and damp conditions.

Mid-Winter Maintenance

Storing your dahlias isn't a "set it and forget it" task. We recommend checking on your tubers once a month during the winter. This simple habit can be the difference between a 100% success rate and a box of disappointment.

The Squeeze Test

Open your containers and pick up a few tubers. They should feel firm. If they feel a little flexible or look wrinkled, they are getting too dry. You can lightly mist the storage medium with a spray bottle of water to add some moisture back into the environment. Be careful not to make it "wet"—just a light dampening is enough.

Spotting Rot Early

Look for any signs of fuzzy mold or soft, dark spots. If you find a tuber that is starting to rot, remove it immediately and throw it away. Check the neighboring tubers to make sure they are still dry and firm. If the storage medium feels soggy, you may need to replace it with fresh, dry material and increase the ventilation of your container.

Watching for Sprouts

As late winter approaches, you might see small white or green "eyes" starting to grow. This is normal and a sign that the tubers are healthy. If the sprouts are getting very long (more than 2 inches), your storage area might be getting too warm. Try to move the containers to a slightly cooler spot to keep them dormant until planting time.

For season-long care basics, see How to Grow and Care for Dahlias.

"A quick monthly check-in allows you to adjust the moisture levels and catch any issues before they spread. It only takes five minutes but saves your entire collection."

Summary of Storage Scenarios

Every home is different. Here is how to match your container to your specific situation:

Scenario A: Your storage area is a dry, heated basement.

• Container: Plastic bin with a lid (no holes or very few).
• Medium: Damp peat moss or vermiculite.
• Why: You need to trap every bit of moisture to keep the tubers from shriveling in the dry air.

Scenario B: Your storage area is a damp, cool cellar or crawl space.

• Container: Cardboard box or open wooden crate.
• Medium: Dry pine shavings or perlite.
• Why: The environment provides the humidity, so the container needs to provide airflow to prevent mold.

Scenario C: You have a very small collection (5-10 tubers).

• Container: Individual paper bags inside a single plastic tub.
• Medium: Wood shavings or newspaper.
• Why: This keeps varieties organized and provides easy access for checking.

Conclusion

Storing dahlia tubers is a rewarding way to expand your garden year after year without starting from scratch. By understanding the relationship between your storage container, your packing medium, and your home's environment, you can take the guesswork out of the process. Whether you choose the moisture-wicking properties of vermiculite or the breathability of a cardboard box, the goal is always the same: a firm, healthy tuber ready for the spring sun.

We take pride in providing high-quality dahlias and the support you need to keep them thriving. Our 100% Quality Guarantee is there to back that up. Remember that gardening is a journey of observation and small adjustments. If one method doesn't work perfectly this year, don't be discouraged. Simply try a different container or a cooler corner of the house next time. Most dahlia enthusiasts find their "perfect" system after a season or two of trial.

As the winter months pass, you can look forward to the return of those vibrant colors. When the ground warms up and the danger of frost has passed, you will be ready to bring your tubers out of hiding and start the cycle of beauty all over again.

• Select a container based on your storage room's humidity.
• Use a medium like peat moss or vermiculite to regulate moisture.
• Keep tubers cool (40-50°F) and never let them freeze.
• Check your storage monthly to mist or remove any rot.

The secret to a spectacular dahlia garden next year is the care you give your tubers today. Take the time to pack them well, and they will reward you with a lifetime of blooms.

FAQ

Can I store dahlia tubers in plastic bags?

Yes, you can store dahlia tubers in plastic bags, but you must be very careful about moisture. Many gardeners use the "Saran wrap" or plastic bag method by wrapping individual, clean tubers tightly. If you choose this route, ensure the tubers are 100% dry before wrapping, as any trapped moisture can lead to rapid rot. For more winter survival guidance, see Can Dahlia Tubers Survive Frost?.

Is it better to store dahlias in peat moss or vermiculite?

Both materials are excellent, but they serve slightly different needs. Peat moss is better for very dry environments because it holds a significant amount of moisture. Vermiculite is often preferred for divided tubers because it is sterile and provides a more consistent balance of air and moisture, though it is usually more expensive.

Should I wash the dirt off my tubers before storing them?

Washing is optional but can be helpful. Removing the soil allows you to inspect the tubers for damage and pests more easily and makes it simpler to find the "eyes" for dividing. However, if you wash them, you must ensure they are completely dry (usually 24–48 hours of air-drying) before placing them in a container, or they will likely rot.

What should I do if my stored tubers are shriveling?

If your tubers look wrinkled or feel flexible, they are losing too much moisture. To fix this, lightly mist the storage medium (the peat moss or shavings) with water using a spray bottle. Do not soak them; you just want to increase the humidity in the container. You can also move the tubers to a less ventilated container, like a plastic bin, to help trap more moisture.