Table of Contents
- Introduction
- Understanding Your Dahlia Tubers
- When Is the Best Time to Save Dahlias?
- Tools for a Successful Harvest
- Step-by-Step: How to Lift and Save Your Dahlias
- The Anatomy of a Viable Tuber
- To Divide or Not to Divide?
- Curing: The Key to Preventing Rot
- Creating the Perfect Winter Storage Environment
- Checking in During the Winter
- Safety and Toxicity Notes
- Hardiness Zones and Shipping
- Planning for Spring: Replanting Your Saved Tubers
- Conclusion
- FAQ
Introduction
There is nothing quite like the joy of seeing your first dahlia of the season unfurl its petals. These spectacular flowers, with their intricate shapes and vibrant colors, are often the crowning achievement of a summer garden. For a closer look at the many ways they can appear, see our dahlia forms guide. Because they bloom so generously from mid-summer through the first frost, it is natural to want to keep that beauty going year after year.
At Longfield Gardens, we believe that gardening should be a rewarding and accessible hobby for everyone, and our dahlia collections make it easy to find a favorite. One of the most common questions we receive as the season winds down is: "Can I save dahlia bulbs?" The answer is a resounding yes. While dahlias are tender perennials that cannot survive freezing temperatures in the ground in most parts of the United States, their tubers are easy to lift and store.
This guide is designed for any gardener who wants to preserve their favorite varieties and even grow their collection for free. When you're ready to add more, shop our spring-planted bulbs. We will walk you through the simple, step-by-step process of identifying, lifting, cleaning, and storing your dahlia tubers so they stay healthy and ready for planting next spring. By learning a few basic winter care techniques, you can enjoy your favorite blooms for many seasons to come.
Understanding Your Dahlia Tubers
While many gardeners use the term "bulbs" to describe the fleshy roots of a dahlia, they are technically tubers. Understanding the difference helps make the saving process much clearer. A true bulb, like a tulip, contains everything the plant needs to grow in one rounded package.
Daffodils are another true bulb. A dahlia tuber is a bit different; it is a thickened, underground part of the stem that serves as a food storage unit for the plant.
When you dig up a dahlia at the end of the season, you won't find just one "bulb." Instead, you will see a cluster of tubers that looks a bit like a bunch of sweet potatoes or carrots. This cluster is attached to the base of the main stem, which is called the crown.
Saving these tubers is a wonderful way to ensure you have the exact same flower colors and forms next year. It is also an economical way to garden. Because dahlias naturally multiply underground during the summer, a single tuber planted in May can often result in a cluster of five or ten tubers by October. This means that by saving your "bulbs," you aren't just keeping your garden the same—you are helping it grow larger and more beautiful every year.
When Is the Best Time to Save Dahlias?
Timing is one of the most important factors when it comes to successfully saving dahlia tubers. In the gardening world, we often say that "timing beats tricks." You don't need fancy equipment to save your dahlias, but you do need to wait for the right signals from nature.
The best time to begin the process is shortly after the first "killing frost." This is the frost that turns the lush green foliage of your dahlias to a dark brown or black. While it might look a bit sad to see your plants wilt, this is actually a helpful sign. When the top of the plant dies back, it signals the tubers underground to enter a state of dormancy.
If you live in a climate where frost comes very late or not at all, you can generally begin the lifting process in late autumn, usually around November. Waiting for the foliage to die back naturally allows the plant to send all its remaining energy down into the tubers. This "energy bank" is what the plant will use to sprout and grow next spring.
Key Takeaway: Wait for the first frost to turn the leaves brown before you dig. This ensures the tubers have stored enough energy to survive the winter and grow vigorously next year.
Tools for a Successful Harvest
You likely already have the tools you need in your garden shed. Using the correct tools makes the job easier and prevents accidental damage to the fragile tubers.
- Garden Fork: A sturdy garden fork (or pitchfork) is often better than a shovel for lifting dahlias. The tines allow you to loosen the soil without cutting into the tubers.
- Pruning Shears: You will need these to cut back the heavy stalks before you begin digging.
- Garden Hose: A gentle stream of water is the best way to clean the soil off the tubers without scrubbing.
- Labels and Markers: This is perhaps the most important tool. Once the tubers are out of the ground and the flowers are gone, all dahlia tubers look very similar. Use waterproof tags or a permanent marker to record the variety name, especially if you're saving a favorite like Cafe Au Lait.
Step-by-Step: How to Lift and Save Your Dahlias
Lifting your dahlias is a straightforward process that can be completed in an afternoon. By following these steps, you can ensure your tubers come out of the ground safely and are prepared for their winter rest.
1. Cut Back the Foliage
Once the frost has turned the plants brown, use your pruning shears to cut the stalks down to about four to six inches above the soil line. This "handle" makes it easier to manage the clump as you lift it. Some gardeners like to leave the cut stalks in the ground for a few days to a week to help the "eyes" (the growth points) become more visible, but you can also proceed immediately if the weather is turning very cold.
2. Loosen the Soil
Start by placing your garden fork about 12 inches away from the base of the stalk. You want to give the tuber cluster plenty of room. Push the fork deep into the soil and gently pry upward. Work your way in a circle all the way around the plant. This slowly breaks the tension of the soil and the smaller feeder roots.
3. Lift the Clump
Once the soil is loose all the way around, gently lift the entire clump out of the ground using the fork and the remaining stem handle. It is important to be gentle during this step. The "necks"—the narrow part where the tuber attaches to the crown—are quite fragile. If a tuber breaks off at the neck, it usually will not be able to grow next year because the growth point remains on the crown.
4. Shake and Rinse
Gently shake off the loose clumps of soil. Using a garden hose with a spray nozzle, wash away the remaining dirt. Getting the tubers clean is helpful because it allows you to see any signs of damage or rot. It also makes it easier to find the "eyes" if you decide to divide them.
What to do next:
- Check each tuber for firm, healthy skin.
- Trim away any long, thin "hair" roots.
- Attach a label to the stem or the tubers immediately so you don't forget which variety is which.
The Anatomy of a Viable Tuber
Not every piece of the root system you dig up will grow into a new plant. To save a dahlia successfully, you need to make sure the piece you keep has three essential parts. We like to think of this as the "Success Trio."
- The Body: This is the large, fleshy part of the tuber. It acts as the fuel tank, providing energy to the plant before it develops its own leaves to perform photosynthesis.
- The Neck: This is the narrow portion that connects the body to the crown. It must be intact and unbroken for the energy to reach the growth point.
- The Crown (and the Eye): The crown is the area at the base of the old stem. This is where the "eyes" are located. An eye is a small bump, much like the eye on a potato, where the new sprout will emerge.
If a tuber has a healthy body and neck but no piece of the crown with an eye, it will stay firm in the ground next year but will never sprout. This is why we recommend keeping the cluster whole if you are a beginner, or ensuring you have a clear piece of the crown attached if you choose to divide.
To Divide or Not to Divide?
One of the most common debates among dahlia enthusiasts is whether to divide the tuber clumps in the fall or wait until the spring. At Longfield Gardens, we believe the best approach is the one that fits your schedule and comfort level.
Dividing in the Fall
Many gardeners prefer to divide their tubers right after digging. The tubers are softer and easier to cut in the autumn. It also saves space in storage because you aren't keeping extra material you won't use. However, the "eyes" can be very difficult to see in the fall, which leads to the risk of accidentally cutting through a growth point.
Dividing in the Spring
Waiting until spring is a very safe option for beginners. After a few months of storage, the tubers naturally begin to wake up. The eyes will swell and sometimes even turn a light pink or green, making them very easy to identify. This ensures that every piece you plant has a guaranteed sprout. The only downside is that the tubers become much tougher and "woody" over the winter, so you will need a very sharp, strong knife to cut them. For a step-by-step refresher, see our How to Divide Dahlia Tubers guide.
Regardless of when you choose to divide, always use a clean, sharp tool. Some gardeners choose to dip their blades in a mild bleach solution or rubbing alcohol between plants to ensure a healthy start for every variety.
Curing: The Key to Preventing Rot
You cannot move dahlia tubers directly from the damp ground to a storage box. They need a short period of "curing" to prepare for their winter nap. Curing simply means letting the tubers dry out slightly so the outer skin can toughen up.
After washing your tubers, place them in a cool, dry area that is protected from direct sunlight and freezing temperatures. A garage, a basement, or a covered porch works well. Turn the clumps upside down so any water trapped in the hollow stems can drain out.
Let them sit for two to three days. You don't want them to become shriveled or bone-dry, but the surface should feel dry to the touch and the skin should feel a bit more leathery. This step is essential because it prevents excess moisture from being trapped in your storage containers, which is the primary cause of rot over the winter.
Key Takeaway: Curing for 48–72 hours allows the skin to toughen and prevents moisture-related issues during storage.
Creating the Perfect Winter Storage Environment
The goal of winter storage is to keep the tubers dormant, cool, and plump. If it is too warm, they might start to grow too early. If it is too cold, they will freeze and perish. If it is too dry, they will shrivel up like raisins.
The Ideal Temperature
The "sweet spot" for dahlia storage is between 40°F and 50°F. This is cool enough to keep them sleeping but well above the freezing point. An unheated basement, a crawl space, or a cool closet in a mudroom are often perfect locations. If you use a garage, make sure it is attached to the house or insulated so that the temperature does not drop below freezing during a cold snap.
Choosing a Storage Container
You have several options for containers, and the best choice often depends on the humidity of your home.
- Cardboard Boxes or Paper Bags: These are great for areas with higher humidity because they allow for some air exchange.
- Plastic Bins: If your storage area is very dry, a plastic bin can help lock in a little more moisture. Just be sure to leave the lid slightly cracked or drill small holes in the sides for ventilation.
- Milk Crates: These provide excellent airflow and are easy to stack if you have a large collection.
Storage Mediums
Most gardeners find that packing the tubers in a "bedding" material helps maintain the perfect moisture balance. We recommend using one of the following:
- Coarse Vermiculite: This is many gardeners' favorite choice because it holds just enough moisture while preventing rot.
- Peat Moss: A classic choice that is easy to find.
- Wood Shavings: The kind used for animal bedding works well and is very affordable.
- Dry Sand: This is heavy but very effective at keeping temperatures stable.
Layer the material in the bottom of your container, place the tubers inside (making sure they aren't touching each other), and cover them with more material. This "nesting" protects them from temperature swings and keeps them from drying out too quickly.
Checking in During the Winter
While it is tempting to "set it and forget it," your dahlias will benefit from a quick check-up once a month. This is a simple task that takes only a few minutes but can save your entire collection.
Open your boxes and gently feel a few tubers.
- If they feel mushy or smell bad: This is a sign of rot. Remove any affected tubers immediately so the rot does not spread to the healthy ones.
- If they feel very shriveled or brittle: The environment is too dry. You can lightly mist the storage medium (not the tubers directly) with a spray bottle of water to add a touch of humidity.
- If they look plump and firm: They are doing perfectly! Simply tuck them back in and check again next month.
Safety and Toxicity Notes
When saving dahlia tubers, it is worth noting that they can be mildly toxic to pets if ingested. While they are not usually considered life-threatening, they can cause skin irritation or stomach upset in dogs and cats. If you have curious pets, it is a good idea to store your tubers in a location that is out of their reach, such as on a high shelf or behind a closed door.
Additionally, if you use any fungicides or storage treatments, always follow the label instructions carefully and wear gloves. Most home gardeners find that clean, dry tubers don't need chemical treatments, but if you choose to use them, safety should always come first.
Hardiness Zones and Shipping
Understanding your USDA hardiness zone is the best way to determine if you must save your dahlia bulbs or if you can leave them in the ground. Dahlias are generally hardy in zones 8 through 11. In these warmer climates, the ground does not freeze deeply enough to harm the tubers, so you can often leave them in the garden with a thick layer of mulch for protection.
However, for gardeners in zones 7 and colder, the ground will freeze, and any dahlia tubers left outside will turn to mush. If you aren't sure which zone you are in, you can easily find a USDA hardiness zone map.
At Longfield Gardens, we use your hardiness zone to time our shipping. We want to ensure that your new tubers arrive at the perfect time for planting in your specific area—usually about two weeks before the ideal planting date. We ship to the 48 contiguous United States and take great care to ensure our plants arrive in prime condition, ready for your garden. For more details, see our shipping information.
Planning for Spring: Replanting Your Saved Tubers
The most exciting part of saving dahlia bulbs is the moment you bring them out of storage in the spring. As the weather warms and the danger of frost passes, you can begin to prepare for planting.
About two to four weeks before your last frost date, move your storage containers to a slightly warmer spot. This gentle warmth signals to the tubers that it is time to wake up. You will see the eyes begin to swell and perhaps even push out tiny sprouts.
When the soil in your garden has warmed to about 60°F, you can plant them exactly as you did when they were new. Dig a hole about 4 to 6 inches deep, lay the tuber horizontally with the eye facing up, and cover it with soil. Within a few weeks, you will see green shoots pushing through the earth, starting the beautiful cycle all over again.
Conclusion
Saving your dahlia bulbs is one of the most rewarding "easy wins" in gardening. It transforms a seasonal flower into a long-term investment that grows more beautiful every year. By waiting for the first frost, lifting carefully with a garden fork, and providing a cool, dry winter home, you can preserve your favorite varieties and enjoy a stunning display of dinnerplate dahlias every summer.
Our team at Longfield Gardens is dedicated to helping you find success in every corner of your yard. We maintain a trial garden where we evaluate the performance of our plants, ensuring that the varieties we provide are of the highest quality and ready to perform for you. We also stand behind them with our 100% Quality Guarantee.
As you head into the autumn season, remember that a little bit of preparation now goes a long way toward a colorful garden next year. Whether you are saving a single favorite 'Cafe au Lait' or a whole collection of dinnerplate dahlias, the process is simple, enjoyable, and incredibly satisfying.
Next Steps for Success:
- Identify your favorite dahlias now so you know which ones to save first.
- Gather your storage supplies (boxes and vermiculite) before the first frost.
- Check your USDA hardiness zone to confirm your local planting and lifting dates.
FAQ
Do I have to dig up my dahlia bulbs every year?
If you live in USDA hardiness zones 7 or colder, yes, you should dig them up. In these regions, the winter temperatures drop low enough to freeze the soil, which will destroy the tubers. In zones 8 and warmer, you can often leave them in the ground if you provide a thick layer of mulch to keep them dry and insulated. For a broader overview of planting and care, see All About Dahlias.
Can I save a tuber if the neck is broken?
Generally, a dahlia tuber with a broken neck will not grow. The "eye," which is the only place a new sprout can emerge, is located on the crown of the plant, not on the body of the tuber itself. If the connection between the body (the food source) and the crown (the growth point) is severed, the tuber cannot provide the energy needed for the sprout to develop.
What is the best material to pack dahlia bulbs in for winter?
Most gardeners find the best results using coarse vermiculite or peat moss. These materials are excellent at regulating moisture; they absorb excess humidity to prevent rot but hold onto enough moisture to keep the tubers from completely shriveling. Wood shavings or dry sand are also popular and effective alternatives.
How do I know if my stored dahlia tubers have gone bad?
A healthy tuber should feel firm, similar to a fresh potato. If a tuber feels soft, mushy, or slimy, it has likely succumbed to rot and should be discarded immediately. If a tuber is extremely shriveled and feels brittle or hollow, it may have dried out too much, though you can sometimes revive slightly shriveled tubers by soaking them in water for an hour before planting in the spring.