Table of Contents
- Introduction
- Why Dahlias Need Winter Storage
- Timing Your Harvest
- How to Dig Dahlia Tubers Safely
- Cleaning and Preparing for Storage
- Identifying the Anatomy: Body, Neck, and Eye
- Choosing a Storage Medium
- The Ideal Storage Environment
- Mid-Winter Check-Ups
- Waking Your Dahlias in Spring
- Creating a More Beautiful Garden
- FAQ
Introduction
Few things in the garden are as rewarding as a dahlia in full bloom.
If you are growing the massive, pillowy blooms of dinnerplate dahlias, these flowers are the undeniable stars of the late summer landscape.
If you love the intricate, geometric petals of pompon varieties, they are every bit as rewarding year after year.
The only thing better than enjoying these blooms once is knowing you can enjoy them year after year. By learning how to store dahlia bulbs in winter, you can preserve your favorite varieties and even grow your dahlia collections over time.
At Longfield Gardens, we want to help you make the most of every plant in your yard and explore our dahlia collection.
Saving your dahlia tubers—which are often called bulbs—is a simple and satisfying way to extend your gardening success. This process is essentially a way of overwintering the plant, keeping the energy-rich tubers safe from freezing temperatures so they can sprout again when the ground warms.
In this guide, we will walk you through everything you need to know about digging, cleaning, and storing your dahlias. This article is designed for home gardeners who want a clear, reliable method for protecting their investment and ensuring a beautiful display next season. Storing your dahlias is an achievable task that turns a seasonal flower into a lifetime garden companion.
Why Dahlias Need Winter Storage
Dahlias are native to the warm climates of Mexico and Central America. Because of their tropical heritage, they have not evolved to survive the deep freezes of a typical North American winter. While the foliage and flowers will die back when the temperature drops, the tubers underground remain alive. If the ground freezes solid, the water inside the tubers expands, causing the cell walls to burst and the tuber to rot.
In USDA hardiness zones 8 and warmer, gardeners can often leave dahlias in the ground with a thick layer of mulch for protection. However, for those of us in zones 7 and colder, digging and storing the tubers is a necessary step. Even in warmer zones, many gardeners choose to dig their dahlias every few years to divide the clumps and improve the health of the plants.
Think of winter storage as a quiet rest period for your dahlias. During these months, the tubers are dormant, meaning they are alive but not actively growing. Our goal is to provide an environment that is cool enough to keep them dormant but warm enough to prevent freezing, while also managing moisture levels to prevent both shriveling and rot.
Timing Your Harvest
One of the most important aspects of knowing how to store dahlia bulbs in winter is getting the timing right. You want to give the tubers as much time as possible to mature and store energy, but you must get them out of the ground before the soil freezes.
The First Frost Signal
The best time to dig up your dahlias is shortly after the first "blackening frost." This is a light frost that kills the tender foliage and turns it dark brown or black, but does not freeze the ground. When the foliage dies, the plant sends a final surge of energy down into the tubers, which helps them survive the winter.
Wait about 5 to 7 days after this frost before you start digging. This short waiting period allows the tubers to "set" their skins, making them tougher and less likely to be damaged during the storage process. If you live in an area where a hard frost comes very late, you can simply dig them up in late October or early November.
Preparing the Stems
Before you pick up a shovel, use a pair of clean garden pruners to cut the dahlia stems down. Leave about 4 to 6 inches of stem protruding from the ground. These "handles" make it much easier to lift the tubers and help you keep track of where each clump is located.
Key Takeaway: Timing is everything. Wait for the first frost to turn the foliage brown, then wait a few days for the tubers to toughen up before you begin the digging process.
How to Dig Dahlia Tubers Safely
Dahlia tubers grow in clumps that expand throughout the summer. They are often larger and more spread out than you might expect. Being gentle during the digging process is the best way to ensure your tubers remain healthy and viable for next year.
Choosing the Right Tools
While a pointed shovel can work, a garden fork (also called a digging fork) is the preferred tool for lifting dahlias. The tines of a fork are less likely to slice through the tubers than a solid shovel blade. If you do use a shovel, be extra cautious about your distance from the center of the plant.
The Lifting Process
Start by inserting your fork into the soil about 12 inches away from the main stem. Gently pry upward to loosen the soil. Move around the plant in a circle, loosening the soil from all sides. This "root pruning" action helps release the clump without snapping the individual tubers.
Once the soil is loose, use the fork to gently lift the entire clump out of the ground. Avoid pulling on the stems, as they can break off at the "neck" of the tuber. The neck is the narrow part where the tuber connects to the main stem, and it is the most fragile part of the plant. If the neck breaks, that specific tuber may not be able to grow an eye next year.
What to Do Next
- Shake off large clumps of loose soil by hand.
- Check each clump for a label. If you didn't label them in summer, do it now!
- Move the lifted clumps to a protected area, like a garage or shed, to begin the cleaning process.
- Avoid leaving the tubers out in the direct sun for more than an hour or two, as they can begin to dry out too quickly.
Cleaning and Preparing for Storage
Once the tubers are out of the ground, they need to be cleaned. While some gardeners prefer to leave a bit of soil on the tubers, most find that washing them makes it easier to spot signs of disease or rot. It also makes it easier to identify the "eyes" if you plan to divide them.
Washing the Tubers
Use a garden hose with a gentle spray nozzle to wash away the remaining soil. You don't need to scrub them; just let the water do the work. If you have heavy clay soil, you might need to use your fingers to gently dislodge mud from the center of the clump.
As you wash, keep an eye out for any tubers that look shriveled, feel mushy, or show signs of insect damage. These should be trimmed away with a clean knife and discarded. Only healthy, firm tubers should go into winter storage.
The Importance of Labeling
Nothing is more frustrating than a box of "mystery dahlias" in the spring. Before the tubers dry, use a waterproof garden marker to write the variety name directly on the skin of each large tuber. Alternatively, you can use plastic nursery tags tied securely to the stem handle with twine.
Curing the Tubers
After washing, the tubers need to "cure" or dry slightly before they are packed away. Place them in a cool, shaded area with plenty of air circulation. An unheated garage or a covered porch works well. Turn them upside down so that any water trapped in the hollow stems can drain out.
Let the tubers dry for 24 to 48 hours. The goal is for the skin to feel dry to the touch, but the tuber itself should still feel firm and heavy, like a fresh potato. If they stay out too long, they will begin to shrivel, which reduces their chances of surviving the winter.
Identifying the Anatomy: Body, Neck, and Eye
To store and eventually divide your dahlias successfully, it helps to understand their anatomy. A viable dahlia tuber consists of three main parts:
- The Body: This is the thick, potato-like part that stores energy and nutrients.
- The Neck: This is the narrow portion that connects the body to the crown.
- The Eye: This is the small bump or "growth point" located on the crown (the area where the neck meets the old stem).
Without an eye, a tuber cannot produce a new plant, even if the body is large and healthy. In the fall, eyes can be very difficult to see—they often look like tiny, dormant pimples. If you aren't confident in your ability to spot them, it is perfectly fine to store the entire clump whole and wait until spring to divide them. By spring, the eyes will begin to swell and turn pink or green, making them much easier to identify.
Key Takeaway: Every tuber needs a "body" for energy, a "neck" for connection, and an "eye" for growth. If you're unsure where the eyes are, store the clump whole.
Choosing a Storage Medium
The biggest challenge of storing dahlias is finding the right balance of moisture. If the environment is too wet, they rot. If it’s too dry, they shrivel and die. Using a storage medium helps regulate this moisture and provides a layer of insulation.
Peat Moss or Coco Coir
This is perhaps the most popular method. Slightly dampen the peat moss or coco coir—it should feel barely moist, not wet. Layer the tubers in a cardboard box or plastic bin, covering each layer with the medium so the tubers are not touching each other.
Vermiculite or Perlite
These mineral-based mediums are excellent for moisture control. They don't hold as much water as peat moss, which can be helpful if you live in a very humid climate or have a basement that tends to stay damp.
Wood Shavings
Pine shavings (the kind sold for animal bedding) are another great option. They allow for excellent air circulation while still providing enough insulation to keep the tubers from drying out completely.
The "Saran Wrap" Method
Some gardeners have success wrapping individual, cleaned tubers tightly in plastic kitchen wrap. This method relies on the tuber's own moisture to keep it plump. It takes up very little space, but it requires the tubers to be perfectly clean and dry on the surface to prevent mold from being trapped inside the wrap.
The Ideal Storage Environment
Where you keep your dahlias is just as important as how you pack them. You are looking for a "Goldilocks" environment: not too hot, not too cold, and just enough humidity.
Temperature Range
The ideal temperature for storing dahlia bulbs is between 40°F and 50°F. If the temperature stays consistently above 55°F, the tubers may try to sprout prematurely or dry out. If the temperature drops below 35°F, you run the risk of the tubers freezing.
Excellent storage locations often include:
- An unheated basement or root cellar.
- A cool closet in a mudroom or utility room.
- An insulated crawl space.
- An insulated garage (provided it does not freeze).
Humidity and Airflow
If you are using cardboard boxes, they will naturally "breathe," allowing some moisture to escape. If you are using plastic bins, do not snap the lids on tight. Leave the lids slightly ajar or drill a few small holes in the sides of the bin to allow for gas exchange and to prevent condensation from building up.
Mid-Winter Check-Ups
Even the best storage setup requires a little bit of maintenance. We recommend checking your dahlia tubers once a month throughout the winter. This allows you to catch small issues before they become big problems.
Troubleshooting Shriveling
If you notice the tubers are starting to look wrinkled or feel light and "corky," they are losing too much moisture. To fix this, lightly mist the storage medium with water. You don't want it to be wet, just slightly damp to the touch. This will increase the local humidity and help the tubers stay plump.
Troubleshooting Rot
If you find a tuber that feels soft, mushy, or has visible fuzzy mold, remove it immediately. Rot can spread quickly from one tuber to another. Use a clean knife to cut away any affected areas on nearby tubers, then let them air dry for a day before repacking them in fresh, dry medium.
What to do during winter checks:
- Feel a few tubers to ensure they are firm.
- Look for any signs of mold or "weeping" moisture.
- Ensure the storage area is still within the 40°F to 50°F range.
- Remove any damaged tubers to protect the rest of the collection.
Waking Your Dahlias in Spring
As the days get longer and the weather warms, your dahlias will naturally start to "wake up." You might see the eyes beginning to swell or even small white sprouts starting to emerge.
In late March or April, you can move your storage bins to a slightly warmer spot to encourage growth. This is also the perfect time to divide your clumps if you didn't do so in the fall. Each division must have at least one healthy eye to be successful.
If you want an early start, you can "pot up" your tubers indoors in containers 4 to 6 weeks before the last frost date, then transplant them into the garden when the weather is settled.
Wait to plant your dahlias outdoors until the soil has warmed to about 60°F and all danger of frost has passed. If you want a refresher on spring planting, see our How to Grow Dahlias from Tubers guide.
Creating a More Beautiful Garden
Gardening is a journey of discovery, and learning to save your own dahlia tubers is one of the most rewarding skills you can acquire. It allows you to build a personal connection with your plants, seeing them through their entire life cycle from spring sprout to winter dormancy.
For a broader overview of planting, care, and seasonal timing, read our All About Dahlias guide.
At Longfield Gardens, we are committed to providing you with the highest quality tubers and the practical knowledge you need to succeed.
We take great pride in our 100% quality guarantee. We ensure our items are true to variety and arrive in prime condition. If you ever have questions about your plants during their first growing season, our team is ready to help with advice or solutions to keep your garden thriving.
When you're ready to plant again, browse our spring-planted bulbs.
You can also check out our new dahlias.
Final Thought: Storing dahlias is a cycle of care that rewards you with bigger, better blooms every year. It’s an easy win for any gardener who loves vibrant color and long-lasting flowers.
FAQ
Can I store dahlias in the refrigerator?
While a refrigerator is cool, it is often too dry for dahlia tubers, and the temperature can sometimes be too low (near 33°F). Furthermore, ripening fruits and vegetables in a fridge release ethylene gas, which can damage or kill the dormant eyes on the tubers. It is better to use a cool basement, crawl space, or insulated garage. For a full storage walkthrough, see our How to Overwinter Dahlias guide.
Should I wash my tubers before storing them?
Washing is generally recommended because it allows you to see the "eyes" and identify any rot or insect damage. However, it is vital that you allow the tubers to dry for 24 to 48 hours after washing so that the surface is dry before they are packed. Storing wet tubers is a primary cause of winter rot.
What if my dahlia tubers shrivel during the winter?
A small amount of shriveling is normal and usually isn't a problem. If they become very wrinkled and soft, you can lightly mist the storage medium (like peat moss) with water to rehydrate the air around them. Most dahlias will "plump up" again once they are planted in moist soil in the spring.
How do I know if a dahlia tuber is dead?
A dead tuber will usually be very mushy and may have a foul odor, or it will be completely dried out and brittle like a piece of hollow wood. Healthy tubers should feel firm, similar to a fresh potato. If you aren't sure, keep the tuber until spring; if it doesn't sprout an eye by May, it is likely no longer viable.