Introduction
Dahlias are the undisputed champions of the late-summer garden. Their spectacular colors and intricate petal patterns provide a sense of joy that lasts right up until the first frost. At Longfield Gardens, we want to help you preserve that beauty so you can enjoy your favorite varieties year after year.
Saving your tubers is a rewarding way to expand your garden without starting from scratch each spring. Browse our dahlias for next season. This guide will walk you through the simple steps of digging, cleaning, and storing your dahlias for the winter months. Whether you are a first-time grower or a seasoned gardener, the process is straightforward and achievable.
By following a few basic steps, you can ensure your tubers stay healthy and ready for a fresh start when the warm weather returns. Saving your tubers is the best way to maintain your collection and guarantee another season of breathtaking blooms. For broader growing tips, see All About Dahlias.
Timing Your Dahlia Harvest
The most important part of saving dahlia tubers is knowing exactly when to start. Because dahlias are native to the warm climates of Mexico and Central America, they are not naturally equipped to survive freezing ground temperatures. In most parts of the United States, this means they must be lifted from the garden and brought indoors. If you're unsure about your climate, check our Hardiness Zone Map.
The signal to begin is usually given by the weather. Most gardeners wait for a "killing frost." This is a frost that turns the lush green foliage of your dahlias black or dark brown. While it might look a bit sad to see your plants wilt, this is actually a helpful part of the plant's life cycle. For a related step-by-step guide, read How Do You Winter Dahlia Bulbs?.
When the top of the plant dies back, the energy from the leaves and stems moves down into the tubers. This process helps the tubers mature and prepares them for their dormant period. It is usually best to wait about a week or two after the first frost before you begin digging. This brief waiting period allows the "eyes" on the tubers to become more visible, which is helpful if you plan to divide them later.
If you live in a region where frost comes very late or not at all, you can still save your tubers. If it is mid-November and you haven't had a frost, you can simply cut the plants back manually. This tells the plant that it is time to rest for the season.
Preparing the Plants for Digging
Once the foliage has died back, your first task is to clear away the bulk of the plant. Use a pair of sharp loppers or garden shears to cut the main stems down. You want to leave a "handle" of about 4 to 6 inches of stem sticking up out of the ground.
These stem handles serve two purposes. First, they provide a convenient way to identify where the center of the tuber clump is located. Second, they give you something to hold onto while you are working. However, you should never use these handles to pull the tubers out of the soil, as dahlia necks are quite fragile.
After cutting the stems, take a moment to ensure your labels are secure. If you have multiple varieties, it is very easy to lose track of which is which once the flowers are gone. We recommend attaching a waterproof tag directly to the remaining stem handle or using a garden marker to write the variety name on the tuber itself after it has been cleaned.
What to do next:
- Check the weather forecast for the first killing frost.
- Gather your tools: sharp loppers, a garden fork, and waterproof labels.
- Cut stems to 4-6 inches and ensure each plant is correctly identified.
How to Dig Your Dahlia Tubers
Digging dahlias is a gentle process that requires a bit of patience. The goal is to lift the entire clump of tubers without snapping the narrow "necks" that connect the tubers to the main stem. If the neck is broken, the tuber may not be able to sprout next year.
A garden fork is generally a better tool for this job than a traditional shovel. The tines of a fork allow you to loosen the soil without accidentally slicing through a tuber. Start by inserting the fork into the soil about 12 inches away from the stem handle. You want to give the root system plenty of space.
Work your way around the plant in a circle, gently prying upward from different angles. This gradually loosens the grip of the soil. Once the clump feels loose, reach under the tubers with your hands or the fork to lift the entire mass out of the ground.
Gently shake the clump to remove the largest pieces of soil. At this stage, the tubers are full of water and can be quite heavy, so handle them with care. If you encounter resistance, do not force the plant upward. Instead, continue loosening the soil further away from the center.
Cleaning and Inspecting the Tubers
Once the tubers are out of the ground, they need to be cleaned. There are two main ways to do this, and the best choice often depends on your soil type. If you have light, sandy soil, you may be able to simply brush the dirt away once it dries. If you have heavy clay soil, washing them with water is usually more effective.
Using a garden hose with a gentle spray nozzle can help remove stubborn dirt from the crevices of the clump. Cleaning the tubers makes it much easier to inspect them for damage or signs of rot. You want to look for firm, healthy-looking tubers.
During your inspection, keep an eye out for any tubers that feel mushy or look shriveled. Use a clean, sharp knife to trim away any broken pieces or "mother" tubers that appear to be decaying. The mother tuber is the original one you planted in the spring; it often starts to break down after it has finished its job of fueling the season's growth.
After washing, turn the clumps upside down for a few hours. This allows any water that collected in the hollow stems to drain out. Preventing water from sitting inside the stem is a simple way to reduce the risk of rot during winter storage.
The Choice to Divide Now or Later
One of the most common questions gardeners ask is whether they should divide their dahlia clumps in the fall or wait until the spring. Both methods work well, and the choice often comes down to personal preference and available storage space.
Dividing in the Fall
Dividing in the fall is a great way to save space. A single clump can produce five to ten individual tubers, each capable of becoming a new plant. If you divide them now, you can store them in much smaller containers.
To divide successfully, every individual tuber must have three things: a "body" (the tuber itself), a "neck," and a piece of the "crown" that contains an "eye." The eye is a small bump or growth point where next year’s stem will emerge. In the fall, eyes can be very small and difficult to see. This is why many gardeners wait a week after the frost to dig, as the eyes often swell slightly during that time.
Dividing in the Spring
If you are new to saving dahlias, storing the clumps whole and dividing them in the spring is often the easier path. By spring, the eyes will have started to sprout, making them very easy to identify. This removes the guesswork and ensures that every piece you plant is viable.
Whole clumps are also slightly more resistant to drying out over the winter. The downside is that they take up more room in your storage area. If you have the space, keeping the clumps whole is a very safe and effective strategy.
Curing and Drying Your Tubers
Before the tubers go into their final storage containers, they need to "cure." Curing is the process of letting the outer skin of the tuber dry and toughen up. This helps protect the moisture inside and makes the tuber more resistant to fungal issues.
Place your cleaned tubers in a cool, shaded area with good airflow. A garage, basement, or covered porch works well, provided the temperature stays above freezing. Avoid placing them in direct sunlight, as this can cause them to dry out too quickly.
The curing process usually takes between 24 and 48 hours. You want the surface of the tuber to feel dry to the touch, but the tuber itself should still feel firm and heavy. If the tubers start to look wrinkled or shriveled, they have been out in the air for too long and should be packed away immediately.
Steps for Curing:
- Drain water from hollow stems by resting clumps upside down.
- Place tubers in a cool, dry, and shaded spot.
- Allow 1 to 2 days for the skin to dry.
- Monitor for shriveling and adjust timing as needed.
Selecting a Storage Medium
Dahlia tubers need a specific environment to survive the winter. They need to stay dormant, which requires cool temperatures, and they need to retain enough moisture so they don't turn into hard, dry husks. At the same time, they cannot be too wet, or they will rot.
The best way to balance these needs is to use a storage medium. This material acts as a buffer, absorbing excess moisture and providing insulation. Common choices include:
- Vermiculite: This is many gardeners' top choice because it is sterile and does an excellent job of regulating moisture.
- Peat Moss: This is widely available and works well, though it can be dusty to work with. If it is very dry, you may need to mist it slightly with water before use.
- Wood Shavings: Coarse wood shavings (the kind sold for animal bedding) provide excellent airflow.
- Pine Bark: Fine-screened pine bark is another natural option that helps maintain a steady environment.
Some gardeners also use the "plastic wrap" method, where individual tubers are wrapped tightly in plastic film. This is a space-saving technique, but it requires careful cleaning and drying to ensure no rot is trapped inside the wrap. For most home gardeners, a box or bin filled with a storage medium is the most reliable approach.
Choosing the Right Container
The container you choose should complement your storage environment. If you are storing your dahlias in a very dry basement, a plastic bin with a lid can help trap moisture and prevent shriveling. If your storage area is naturally damp, like a root cellar, a cardboard box or a wooden crate will allow for better airflow.
When packing, start with a 2-inch layer of your chosen storage medium at the bottom of the container. Place your tubers or clumps on top, making sure they are not touching each other. This prevents a single spot of rot from spreading to the whole batch. Cover them with more medium and repeat the process if you have multiple layers.
Be sure to label the outside of the box with the varieties inside. It is also helpful to include the date so you can keep track of your garden's progress over the years.
The Ideal Storage Environment
Success with dahlia storage depends largely on temperature and humidity. The "goldilocks" zone for dahlia tubers is between 40°F and 45°F.
If the temperature drops below freezing, the water inside the tubers will freeze and expand, destroying the cell walls. When they thaw, the tubers will turn into mush. Conversely, if the temperature stays above 50°F, the tubers may think it is spring and start to sprout prematurely, or they may simply dry out and die.
Humidity should ideally be around 80% to 90%. While this sounds high, the goal is simply to keep the air around the tubers from being bone-dry. Storing them in a medium inside a container usually creates this micro-climate naturally.
Good storage locations include:
- An unheated (but attached) garage.
- A cool, dark corner of a basement away from the furnace.
- An insulated garden shed.
- A dedicated root cellar.
Monitoring Your Tubers Through Winter
Saving dahlia tubers is not a "set it and forget it" task. We recommend checking on your tubers about once a month. This small effort can make a huge difference in your success rate.
When you open your storage containers, look for two things: rot and shriveling. If you find a tuber that has developed a soft, mushy spot, remove it immediately and throw it away. If the rot is only on a small tip, you can sometimes cut it back to healthy tissue and let it dry before putting it back.
If the tubers look shriveled or feel light, they are losing too much moisture. You can fix this by lightly misting the storage medium with a spray bottle of water. Do not soak the medium; you just want to add a tiny bit of humidity back into the air. If they look plump and firm, everything is going perfectly.
Winter Check-List:
- Set a monthly reminder on your calendar.
- Inspect for soft spots or mold.
- Check for excessive shriveling.
- Mist lightly with water only if the medium feels completely dry.
Preparing for Spring
As winter draws to a close, you will notice the eyes on your tubers beginning to swell and perhaps turn a light pink or green. This is an exciting sign that your dahlias are ready for another year in the sun.
About four to six weeks before the last expected frost, you can bring your tubers into a warmer area to wake them up. This is the perfect time to divide any large clumps you stored whole. If you find that you have more tubers than you have space for, dahlia tubers make wonderful gifts for friends and neighbors.
When the soil in your garden warms up to about 60°F, you can plant your saved tubers back into the ground. For planting details, see How to Plant Dahlias. They will grow quickly, fueled by the energy they stored over the winter.
Summary of Success
Saving dahlia tubers is a cycle that connects one gardening season to the next. By following the natural rhythms of the plant and providing a cool, stable environment for the winter, you can grow a magnificent garden that evolves every year. For a fuller range of options, browse our dahlia collections.
Longfield Gardens is proud to provide the high-quality plants and practical advice you need to succeed. With a little bit of care during the harvest and storage process, your dahlias will continue to be the star of your summer landscape. If you love huge blooms, explore Dinnerplate Dahlias.
Final Takeaways:
- Wait for the first frost to signal the start of the harvest.
- Dig carefully with a fork to protect the fragile necks of the tubers.
- Store in a cool, dark place between 40°F and 45°F.
- Check monthly to ensure your tubers remain firm and healthy.
Your journey with dahlias doesn't have to end when the first frost arrives. In fact, for many gardeners, the process of saving and potentially multiplying their collection is one of the most satisfying parts of the hobby. For more dramatic forms, see Cactus & Semi-Cactus Dahlias. We encourage you to try these steps this season and look forward to the beautiful results next summer.
FAQ
How do I know if a dahlia tuber is still good in the spring?
A healthy tuber should feel firm to the touch, similar to a fresh potato or a carrot. If it is extremely soft, mushy, or smells bad, it has likely rotted and should be discarded. A little bit of surface wrinkling is normal, as long as the tuber still has some weight and "heft" to it. Most importantly, look for a small sprout or "eye" near the top where the tuber meets the stem; this is the sign that the plant is ready to grow. For rounded blooms, try Ball Dahlias.
Can I store dahlias in the refrigerator?
While a refrigerator maintains a safe temperature for tubers, it is generally too dry for long-term storage. Most modern refrigerators are designed to remove humidity, which can cause dahlia tubers to shrivel and die. If you have no other cool place, you can use a refrigerator, but you must be extra diligent about packing the tubers in a moisture-retentive medium like vermiculite inside a sealed plastic bag. For smaller, rounded blooms, see PomPon Dahlias.
Do I have to wash the dirt off before storing?
You do not strictly have to wash the tubers, but it is highly recommended. Washing removes soil-borne pathogens and makes it much easier to see the "eyes" and identify any signs of rot or insect damage. If your soil is very loose and sandy, you can get away with just brushing them off, but for most gardeners, a quick rinse with a hose provides the cleanest start for winter storage.
What happens if I don't dig up my dahlias?
In USDA zones 8 and warmer, dahlias can often survive the winter in the ground if the soil stays relatively dry and doesn't freeze deeply. However, in zones 7 and colder, the freezing temperatures will turn the tubers into mush, and they will not return in the spring. Even in warmer zones, many gardeners choose to dig and divide their tubers every few years to prevent the clumps from becoming overcrowded and producing smaller flowers.
