Introduction
There is nothing quite like the sight of a dahlia in full bloom. These garden stars produce some of the most spectacular flowers of the season, offering a dizzying array of colors, shapes, and sizes that last from midsummer right up until the first frost. 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. For a big-bloom option, see our Dahlia Dinnerplate Cloud Nine Collection.
While dahlias are easy to grow, they are sensitive to freezing temperatures because they are native to the warmer climates of Mexico and Central America. In most parts of the United States, this means the tubers—often called bulbs by home gardeners—need a little extra care to make it through the winter. Saving your tubers is a rewarding way to build your collection and ensure your favorite blooms return even bigger and better next season.
This guide will walk you through the simple, step-by-step process of lifting, curing, and storing your dahlia tubers. Whether you are a first-time gardener or a seasoned pro, we will show you how to keep your plants safe and dormant until the spring sun warms the soil again. To understand the plant itself, start with All About Dahlias.
Understanding the Dahlia Life Cycle
To store dahlia tubers successfully, it helps to understand what the plant is doing as the seasons change. During the summer, the dahlia focuses all its energy on producing lush foliage and vibrant flowers. As the days grow shorter and the temperatures drop in autumn, the plant begins to shift its energy downward into the root system.
These roots, known as tubers, act as a storage cellar for the plant. They pack away starches and nutrients that will fuel next year’s growth. In warm climates (typically USDA hardiness zones 8 through 11), the ground stays warm enough that the tubers can stay in the soil all winter. However, in zones 7 and colder, the freezing ground will turn these moisture-rich tubers into mush.
Storing them indoors is simply a way of mimicking a mild winter. You are looking to provide a stable, cool, and slightly humid environment where the tubers can "sleep" without freezing or drying out.
When to Dig Your Dahlia Tubers
Timing is one of the most important factors when learning how to store dahlia bulbs for winter. If you dig too early, the tubers may not have stored enough energy to sprout in the spring. If you wait too long, a deep freeze could damage the crowns. For more on tubers and eyes, see Dahlia Tubers: What You Need to Know.
The Frost Signal
The most common signal to begin the process is the first "killing frost." This is the night when temperatures drop just low enough to turn the dahlia’s green leaves and bright flowers into a dark, wilted brown. While it might look a bit sad, this is actually a helpful turning point.
When the foliage dies back, it tells the tubers to go into deep dormancy. Most experienced gardeners prefer to wait about 5 to 10 days after this first frost before they start digging. This brief waiting period allows the tubers to "cure" slightly in the ground, which toughens their skin and makes them more resilient during storage.
Working with Your Local Weather
If your area doesn’t get a hard frost until very late in the year, you can still begin the process in late October or early November. The goal is to get the tubers out of the ground before the soil itself freezes solid. If a heavy freeze is predicted and your dahlias are still green, it is perfectly fine to cut them back and dig them up a bit early to keep them safe.
Key Takeaway: Wait for the first frost to turn the foliage brown, then give the tubers about a week in the ground to toughen up before you begin digging.
Step 1: Cutting Back the Plants
Before you reach for your shovel, you need to clear away the summer growth. This makes the digging process much easier and helps you see exactly where the base of the plant is located.
Using a pair of clean, sharp loppers or garden shears, cut the main stalks down so only about 4 to 6 inches of the stem remains above the soil line. These short stems act as "handles" that help you identify the center of the tuber clump, but you should avoid pulling on them with too much force.
Dahlia stems are hollow, so after you cut them, you might notice some water trapped inside. This is normal. Some gardeners like to cover the cut stems with a bit of foil if they are leaving them in the ground for a few days to prevent too much moisture from entering the crown, but this is usually an optional step.
Step 2: Lifting the Tubers Gently
Dahlia tubers grow in a cluster, often spreading out 12 inches or more from the main stem. They are surprisingly fragile and can snap easily, so the "right plant, right place" philosophy extends to how you handle them.
Choosing the Best Tool
A garden fork (sometimes called a pitchfork) is generally better than a shovel for this task. The tines of a fork allow you to loosen the soil without creating a solid "cutting" edge that might slice through a tuber.
The Lifting Technique
- Give them space: Start by inserting your fork into the soil about 12 inches away from the main stem.
- Loosen the circle: Work your way around the entire plant, gently prying upward to loosen the earth.
- Lift from beneath: Once the soil is loose, slide the fork deep under the center of the clump and lift the entire mass of tubers and soil upward.
- Avoid the handle: Use your hand to support the clump from underneath rather than pulling solely on the cut stem. The point where the tubers meet the stem (the "neck") is the most fragile part.
What to do next:
- Clear away the dead foliage and compost it (unless it shows signs of disease).
- Mark your fork at the 12-inch point to ensure you stay far enough away from the tubers.
- Slowly work in a circle to avoid snapping the "necks" of the tubers.
Step 3: Cleaning and Initial Drying
Once the tubers are out of the ground, they will likely be covered in clumps of soil. How much you clean them depends on your soil type and your preferred storage method.
Removing Soil
If you have sandy soil, you can often just shake the clump gently, and the dirt will fall away. If you have heavy clay soil, you might need to use your fingers or a small wooden stick to poke away the large chunks.
Some gardeners prefer to wash their tubers with a gentle stream from a garden hose. This makes it much easier to see the "eyes" (the small bumps where next year’s growth will start). If you do wash them, it is vital that you let them dry completely before putting them into storage. Moisture trapped against the skin is the primary cause of rot.
The Short-Term Dry (Curing)
Place your lifted clumps in a protected area that is out of direct sunlight but has good airflow. A garage, a covered porch, or a basement floor works well. Lay them out on a piece of cardboard or a mesh screen.
Let them sit for 24 to 48 hours. This allows the outer skin to dry and any remaining soil to become crumbly. Do not leave them out in the sun for long periods, as this can "cook" the tubers or cause them to shrivel prematurely.
Step 4: To Divide or Not to Divide?
One of the most common questions about how to store dahlia bulbs for winter is whether you should cut the clumps into individual tubers now or wait until spring.
Storing the Whole Clump
Many home gardeners choose to store the entire clump just as it came out of the ground. This is the simplest method and often results in less shriveling. The clump protects the "eyes" in the center. The only downside is that whole clumps take up more space in your storage containers.
Dividing in the Fall
If you have a large collection and limited space, you may want to divide the tubers in the autumn. To do this, you use a sharp, sterilized knife to cut individual tubers away from the main stem.
Each tuber must have a "neck" and a piece of the "crown" (the part of the stem where the tuber was attached). If a tuber breaks off without a piece of the crown, it will not have an "eye" and will never grow, even if it looks healthy.
If you divide in the fall, let the cut pieces dry for an extra day so the wounds can "callus" over. This creates a natural barrier against rot.
Step 5: Identifying the "Eyes"
If you decide to divide your dahlias, you need to find the eyes. These are small, slightly raised bumps located on the crown of the tuber. They look very similar to the eyes on a potato.
In the fall, these eyes can be very small and difficult to see. This is why many gardeners wait until spring to divide their tubers, as the eyes begin to swell and turn pink or green as the weather warms, making them much easier to spot. If you aren't sure where the eyes are, it is always safer to leave the clump whole or cut it into larger "chunks" rather than individual tubers.
Step 6: Choosing a Storage Medium
You cannot simply toss dahlia tubers into a plastic bag and hope for the best. They need a "bedding" material that balances two conflicting needs: it must stay dry enough to prevent rot, but moist enough to prevent the tubers from turning into hard, dry raisins.
Commonly used storage mediums include:
- Peat Moss: This is the most popular choice. It is naturally slightly acidic and holds a tiny bit of moisture while remaining breathable.
- Vermiculite: This lightweight mineral is excellent for moisture control. It is very clean and easy to work with.
- Wood Shavings: Pine or cedar shavings (the kind sold for animal bedding) are affordable and provide great airflow.
- Newspaper: Wrapping individual tubers or clumps in several layers of newspaper is a simple, low-cost method that works well in environments with moderate humidity.
Step 7: Packing the Tubers for Winter
Once your tubers are clean, dry, and your medium is ready, it is time to pack them away.
- Select a container: Cardboard boxes, plastic bins (with the lids left slightly ajar), or paper bags are all good options. Avoid airtight containers, as the tubers are living things that need to breathe.
- Layer the medium: Place about 2 inches of your chosen medium at the bottom of the container.
- Arrange the tubers: Lay the tubers or clumps on top of the medium. Try to keep them from touching each other if possible. This ensures that if one tuber develops rot, it won't immediately spread to its neighbors.
- Cover them up: Add more medium until the tubers are completely covered.
- Label everything: This is a step you don't want to skip! Use a permanent marker to write the variety name on a tag or directly on the tuber with a soft pencil. You will be very glad you did this come springtime.
Key Takeaway: The goal of packing is to create a stable environment where the tubers stay hydrated but have enough airflow to prevent mold and rot.
Step 8: Finding the Perfect Storage Spot
The "right place" for your stored dahlias is a spot that stays consistently cool but never freezes.
Temperature Targets
The ideal temperature range is between 40°F and 50°F.
- If it’s too cold (below 35°F): The water inside the tuber cells will freeze, expand, and burst the cell walls. When the tuber thaws, it will turn into a black, watery mess.
- If it’s too warm (above 55°F): The tubers may try to wake up and grow prematurely, or they may simply dry out and shrivel because their metabolic rate is too high.
Humidity Levels
A humidity level of around 80% to 90% is ideal. Most unheated basements, root cellars, or insulated garages stay within a safe range. If your storage area is very dry (like a closet near a furnace), you may need to check your tubers more often.
Step 9: Winter Monitoring and Maintenance
Storing dahlia tubers 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 issues before they become big problems.
What to Look For
- Signs of Rot: If a tuber feels mushy, looks black, or has a fuzzy mold growing on it, remove it immediately. Use a clean knife to cut away any affected parts of a clump, or simply discard the individual tuber.
- Signs of Shriveling: If the tubers look wrinkled like a prune or feel very 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; a tiny bit of humidity goes a long way.
If you notice a lot of condensation on the inside of a plastic bin, it means there isn't enough airflow. Leave the lid off for a day to let the excess moisture escape.
What to do next:
- Set a monthly reminder on your phone or calendar to check your storage boxes.
- Keep a spray bottle nearby for quick moisture adjustments.
- Have a "quarantine" box ready for any tubers that look questionable.
Common Mistakes to Avoid
Gardening is a learning process, and even experts lose a few tubers over the winter. However, avoiding these common pitfalls will greatly increase your success rate:
- Digging too early: If the plant hasn't had time to store energy, the tubers will be small and prone to shriveling.
- Storing "wet" tubers: If you wash your tubers, they must be bone-dry to the touch before they go into a box.
- Using airtight plastic: Without airflow, the natural respiration of the tubers creates moisture, which leads to rot.
- Forgeting the labels: Most dahlia tubers look identical once they are out of the ground. Don't rely on your memory—label as you go!
Safety Considerations
While dahlias are a joy in the garden, it is important to remember that the tubers are not meant for consumption. Keep your stored tubers out of reach of curious pets and small children. Some plants can cause digestive upset if ingested, so it is always best to store them in a secure area away from food storage.
Preparing for Spring
As winter fades and the ground begins to thaw, you can start thinking about the upcoming season. Around late March or April, you can move your storage containers to a slightly warmer spot to encourage the eyes to wake up.
When you see those tiny pink sprouts beginning to emerge, you know you have successfully mastered how to store dahlia bulbs for winter. You can then divide any large clumps you saved whole, ensuring every piece has a healthy sprout.
Wait until the soil in your garden reaches about 60°F before planting them back outside. Planting too early into cold, wet spring soil can cause the tubers to rot before they even get started. Patience is the key to a successful start.
Conclusion
Storing dahlia tubers is one of the most satisfying "circular" tasks in the garden. It connects the beauty of last year’s blooms to the promise of next year’s growth. By taking the time to lift, clean, and protect your tubers, you are ensuring that your garden remains a vibrant, colorful sanctuary year after year.
At Longfield Gardens, our goal is to make these tasks feel accessible and enjoyable. Our 100% guarantee is there to give you extra confidence when you shop. Gardening shouldn't be a source of stress; it’s a way to slow down and work with the natural rhythms of the seasons. With the right timing and a cool, dark corner of your basement, you can preserve your favorite dahlia varieties for many seasons to come.
- Wait for the frost to signal the end of the season. See Dahlia Dinnerplate Summer Lovin Collection.
- Lift gently using a garden fork to protect the tubers. See Dahlia Cactus Tahiti Sunrise.
- Cure and dry thoroughly before packing. See Dahlia Decorative American Sun.
- Store in a cool, dark spot between 40°F and 50°F. See Dahlia Waterlily Priceless Pink.
The secret to dahlia success isn't a complex chemical or a hidden trick—it’s simply giving the tubers a safe, quiet place to rest until the sun returns.
We invite you to explore our selection of premium dahlia tubers and other spring-planted bulbs to keep your garden glowing all season long.
FAQ
Can I leave my dahlias in the ground if I mulch them heavily?
This depends entirely on your USDA hardiness zone. If you live in Zone 8 or warmer, a thick layer of mulch (about 4 to 6 inches) can often protect dahlias through a mild winter. However, in Zone 7 or colder, the frost will likely penetrate the mulch and freeze the tubers, so lifting them is the safest option.
What should I do if my tubers look shriveled in mid-winter?
Shriveling is a sign that the storage environment is too dry. You can lightly mist the packing medium (peat moss or shavings) with a spray bottle of water to increase the humidity. Be careful not to make the medium "wet," as this can encourage rot; a very slight dampness is all they need to rehydrate.
Is it better to wash the dirt off or leave it on?
Both methods can work well. Leaving some soil on can help protect the tubers from drying out, which is helpful if your storage area has low humidity. Washing them makes it much easier to inspect for damage and find the "eyes" for dividing, but you must ensure they are completely dry before storage to prevent mold.
My dahlia tubers have no sprouts in the spring. Are they dead?
Not necessarily! Some dahlia varieties are slower to "wake up" than others. If the tuber is still firm and doesn't feel hollow or mushy, it is likely still viable. You can try placing it in a warm, bright spot or potting it up in some lightly damp soil to encourage the eyes to emerge.
