Introduction
There is nothing quite like the late-summer glory of a dahlia garden. From the massive, pillowy petals of dinnerplate varieties to the intricate, geometric patterns of pompons, these plants are the undisputed stars of the autumn landscape. As the season winds down and the nights grow crisp, many gardeners feel a sense of accomplishment for the beautiful displays they have nurtured. One of the most rewarding parts of growing these stunning flowers is knowing that the story doesn't have to end with the first frost.
At Longfield Gardens, we believe that gardening is a journey of discovery and joy. Saving your dahlia tubers is a wonderful way to preserve your favorite varieties and expand your garden for the following year. While these plants are native to the warm climates of Mexico and Central America, they are easy to "overwinter" in cooler climates with just a little bit of care. Think of this process as tucking your plants in for a long, well-deserved nap.
This guide will walk you through the straightforward process of lifting, cleaning, and storing your tubers. Whether you are a first-time grower or a seasoned gardener looking to refine your technique, we have designed these steps to be simple and effective. By following a few basic principles, you can ensure that your dahlia collection returns even bigger and better next spring.
Learning how to dig up dahlia bulbs is a satisfying skill that turns a one-season plant into a lifelong garden companion.
Understanding the Life Cycle of a Dahlia Tuber
To be successful with dahlias, it helps to understand what is happening beneath the soil. While we often call them "bulbs," dahlias actually grow from tubers. These are thickened, underground parts of the stem that act as storage organs, holding nutrients and moisture to help the plant survive and sprout again.
Throughout the summer, a single dahlia tuber grows into a lush plant and simultaneously produces a "clump" of new tubers underground. By the end of the season, what started as one small tuber can become a cluster of five, ten, or even twenty. Digging them up allows you to protect this investment from freezing temperatures, which would otherwise cause the moisture-rich tubers to turn to mush.
The timing of this process is guided by the weather. In most parts of the United States, dahlias are treated as annuals unless the tubers are lifted and moved to a frost-free location. This transition from the garden to the storage bin is a natural part of the gardening rhythm. It marks the end of the blooming season and the beginning of the planning phase for next year’s color palette.
When Is the Right Time to Dig?
One of the most common questions we receive is exactly when the digging should begin. While it might be tempting to start as soon as the weather turns chilly, patience is a virtue in the dahlia garden. The tubers use the final weeks of the growing season to bulk up and mature, which helps them survive the winter.
The Signal of the First Frost
The best indicator that it is time to dig is the first killing frost. This is the frost that turns the lush green foliage of your dahlias to black or dark brown. While it might look a bit sad at first, this is actually a helpful signal from nature. It tells the plant to stop sending energy to the leaves and flowers and to focus entirely on the tubers.
Once the foliage has turned, you don't need to rush out with a shovel immediately. In fact, many experienced gardeners prefer to wait about a week to ten days after the frost before digging. This short waiting period allows the "eyes" of the tubers to become more prominent. The eyes are the small buds from which next year's stems will grow. If you plan on dividing your tubers later, seeing these eyes is very helpful.
Watching the Calendar
If you live in a region where a hard frost doesn't arrive until very late in the year, you can use the calendar as your guide. Aim to have your tubers out of the ground by mid-to-late November. You want the soil to be cool, but you must get them out before the ground itself freezes solid. If the soil freezes, it can damage the tubers just as much as the air temperature.
Curing in the Ground
The week or so that the tubers spend in the ground after the foliage is cut back is often called curing. During this time, the outer skin of the tuber begins to toughen up slightly. A tougher skin acts as a better barrier against rot and dehydration during the long winter months. If a heavy rainstorm is in the forecast, however, it is better to dig a little early than to let the tubers sit in soggy, waterlogged soil.
Key Takeaway: Wait for the first frost to turn the foliage black, then allow the tubers to sit in the soil for about a week to help them mature before digging.
Essential Tools for Success
Before you head out to the garden, gathering the right tools will make the job much easier and safer for the plants. You don't need specialized equipment, but choosing the right version of common garden tools can prevent accidental damage to the fragile tubers.
- Loppers or Heavy-Duty Pruners: You will need these to cut through the thick, woody stems of the dahlia plants. Some dinnerplate varieties can have stems nearly two inches thick!
- A Garden Pitchfork: This is perhaps the most important tool for the job. A pitchfork is much better than a traditional spade or shovel because the tines can slide through the soil without slicing into the tubers.
- A Garden Hose: A gentle stream of water is the best way to clean the soil off the clumps once they are out of the ground.
- Labels and a Permanent Marker: This is the step most people forget. Once the tubers are out of the soil and the flowers are gone, all tubers look remarkably similar. Labeling them immediately ensures you know which color is which next spring.
- Crates or Trays: You will need a place to set the tubers while they dry. Plastic milk crates or mesh bulb trays are ideal because they allow air to circulate around all sides of the clump.
Step-by-Step: How to Dig Up Dahlia Bulbs
Digging is a physical task, but it shouldn't be a stressful one. If you approach it methodically, you can clear a large bed of dahlias in just a few hours.
Step 1: Cutting Back the Stalks
Start by cutting the main stalk of the plant down to about 4 to 6 inches above the soil line. This remaining piece of stem serves two purposes: it acts as a handle for lifting the clump, and it helps you locate exactly where the center of the tuber cluster is.
Be aware that dahlia stems are hollow. After you cut them, they may have a bit of water trapped inside. This is normal and nothing to worry about at this stage.
Step 2: Loosening the Soil
This is where the garden fork comes into play. You want to avoid "stabbing" the tubers, so you must dig much further away from the stem than you might expect. A good rule of thumb is to start your fork about 12 inches away from the base of the stem.
Push the fork deep into the soil and gently pry upward. Work your way in a circle all the way around the plant. This loosens the "feeder roots"—the thin, hair-like roots that the plant uses for water—and frees the larger tubers from the earth's grip.
Step 3: Lifting the Clump
Once you have loosened the soil in a full circle, you can begin to lift. Place your fork deep under the center of the clump and use one hand to grasp the "stem handle" you left behind. Gently lift the entire mass of soil and tubers out of the ground.
If the clump feels stuck, do not pull hard on the stem. This can snap the "necks" of the tubers. The neck is the thin part connecting the tuber to the main stem, and it is the most fragile part of the plant. If the neck breaks, the tuber may not be able to grow next year. Instead, go back with your fork and loosen the soil a bit more.
Step 4: Shaking Off Excess Soil
Once the clump is out, give it a gentle shake to remove the largest chunks of dirt. You can also use a small stick or a dull tool to poke away soil trapped between the tubers. Be careful not to nick the skin. Even a small cut can be an entry point for fungus during storage.
What to Do Next:
- Cut stems to 5 inches.
- Dig a wide 12-inch circle around the plant.
- Lift from below while supporting the stem.
- Gently shake off loose dirt.
Cleaning and Preparing for Storage
Now that your tubers are out of the ground, they need a little bit of "spa treatment" before they go into storage. This stage is crucial for preventing rot and disease.
Washing the Tubers
Using a garden hose with a gentle spray nozzle, wash the remaining soil off the tubers. It is much easier to see the condition of the tubers when they are clean. Look for any signs of damage or rot. If you find a tuber that feels soft, mushy, or looks like it is decaying, simply snip it off and discard it.
Washing also helps remove any garden pests that might be trying to hitch a ride into your storage area. Slugs and certain insect larvae like to hide in the crevices of dahlia clumps, so a good rinse keeps your storage space clean.
Trimming the Roots
You will notice many thin, stringy roots hanging off the main tubers. These are no longer needed and will only shrivel up and potentially mold in storage. Use a clean pair of snips to trim these away. You can also trim the main stem down a bit further now, leaving about 2 inches of the original stalk.
The Upside-Down Drain
As mentioned earlier, dahlia stems are hollow. If water stays trapped inside that hollow tube, it can lead to "crown rot," which destroys the part of the plant where the eyes are located. To prevent this, turn your clean clumps upside down (stems pointing toward the ground) on a tray or crate. Let them sit like this for at least 24 hours to ensure all moisture drains out.
The Importance of Curing and Drying
Before you pack the tubers away into boxes or bins, they must be "cured." This is a drying process that happens in a protected environment.
Find a spot that is out of direct sunlight but has good air circulation—a garage, a shed, or a covered porch works perfectly. Avoid placing them directly on a concrete floor, as concrete can actually pull too much moisture out of the tubers, causing them to shrivel. Instead, place them on a wooden table, a piece of cardboard, or in plastic crates.
The curing process usually takes between 3 and 7 days. You are looking for the skin to feel dry to the touch and for any remaining soil to be completely desiccated. The tubers should still feel firm, like a fresh potato. If they start to look shriveled like a prune, they are getting too dry and should be packed away immediately.
To Divide or Not to Divide?
One of the biggest debates in the dahlia world is whether to divide the tubers in the fall or wait until the spring. At Longfield Gardens, we want to make gardening as simple as possible, so we suggest choosing the method that fits your schedule and comfort level.
Dividing in the Fall
Some gardeners prefer to divide their clumps into individual tubers right after digging. The advantage here is that the tubers are still relatively soft and easy to cut. It also saves a tremendous amount of space in storage. However, the "eyes" can be very difficult to see in the fall, and if you cut a tuber that doesn't have an eye, it will never grow.
Dividing in the Spring (The Easy Way)
For most home gardeners, we recommend storing the clumps whole and dividing them in the spring. By late March or April, the eyes will begin to swell and may even turn slightly pink or green. This makes it incredibly easy to see exactly where to make your cuts. Storing the whole clump also provides a bit of a "safety net"—if one tuber in the clump dries out, the others are likely to remain healthy.
How to Identify an Eye
If you do decide to divide, look for the "crown" of the plant. This is the area where the tuber meets the main stem. The eye looks like a tiny bump or a "pimple." Every individual tuber must have a piece of that crown containing at least one eye to be viable for next year.
Choosing the Right Storage Environment
Successful storage is all about balance. You want to keep the tubers cool enough to stay dormant, but warm enough that they don't freeze. You also want to keep them dry enough to prevent rot, but humid enough that they don't shrivel.
The Ideal Temperature
The "goldilocks" temperature for dahlia storage is between 40°F and 45°F. This is roughly the temperature of a standard refrigerator. An unheated basement, a crawl space, or a root cellar is usually the best spot. If you store them in a garage, make sure the temperature doesn't drop below freezing during a winter cold snap.
Storage Mediums
You shouldn't just toss the tubers into an empty plastic bin. They need a "medium" to help regulate moisture. Popular choices include:
- Coarse Vermiculite: This is widely considered the best option as it holds just enough moisture while allowing for air exchange.
- Peat Moss: A classic choice, though it can sometimes be a bit too dry.
- Wood Shavings: The kind used for animal bedding works well and is very affordable.
- Newspaper: Some gardeners find success simply wrapping each clump in several layers of newspaper.
Packing the Bins
Place a layer of your chosen medium in the bottom of a cardboard box or a plastic bin. If using plastic, do not seal the lid tightly; leave it cracked or drill a few small holes in the sides to allow for ventilation. Arrange the tubers so they are not touching each other, then cover them with more medium.
Key Takeaway: The ideal storage setup is a cool (40-45°F) dark place with tubers tucked into a breathable medium like vermiculite or peat moss.
Monitoring Your Tubers Through Winter
Gardening doesn't completely stop in the winter; it just moves indoors. It is a great idea to check on your dahlia tubers about once a month. This small effort can save your entire collection if conditions aren't quite right.
Checking for Rot
If you find a tuber that has turned soft or smells bad, remove it immediately. Rot can spread from one tuber to the next very quickly. By catching it early, you protect the rest of the clump.
Checking for Dehydration
If the tubers are starting to look very wrinkled or feel light and airy, they are losing too much moisture. You can lightly mist the storage medium with a spray bottle of water. You don't want it to be wet—just slightly damp to the touch. This "drink" will help the tubers plump back up.
Preparing for Spring Replanting
As the days get longer and the ground begins to thaw, the excitement for the new season begins to build. About a month before your last expected frost, you can bring your dahlia tubers out of storage.
This is the perfect time to divide those large clumps if you haven't already. You can also "pre-start" your dahlias in pots indoors if you want to get a head start on blooms. By the time the soil in your garden warms up to about 60°F, your dahlias will be ready to go back into the earth, continuing the beautiful cycle you started the year before.
Remember that every garden is a bit different. Your local humidity levels and specific storage spot will play a role in how your tubers fare. Don't be afraid to experiment with different storage mediums to find what works best in your home.
Conclusion
Learning how to dig up dahlia bulbs is one of the most practical and satisfying tasks in the garden. It transforms a seasonal flower into a permanent part of your landscape and allows you to share tubers with friends and neighbors. While the process involves several steps, none of them are difficult. By timing your harvest with the frost, cleaning the tubers gently, and providing a cool, stable winter home, you are setting the stage for a spectacular summer ahead.
At Longfield Gardens, we take pride in providing high-quality dahlias that bring beauty to your home year after year. Our 100% quality guarantee ensures that you start each season with healthy, vibrant plants. We are here to support you with practical advice and premium varieties so that your garden is always a source of joy.
- Wait for the first frost to signal dormancy.
- Use a pitchfork to dig wide and lift carefully.
- Dry and "cure" tubers before packing them away.
- Store in a cool, dark place between 40-45°F.
- Check monthly for moisture and health.
We are committed to your success, and we can’t wait to see the incredible dahlia displays you create next season. Happy gardening!
FAQ
Can I leave my dahlia tubers in the ground over winter?
In USDA hardiness zones 8 and warmer, dahlias can often survive the winter in the ground if the soil is well-drained and a thick layer of mulch is applied. However, for gardeners in zones 7 and colder, the ground will freeze deep enough to kill the tubers, making it necessary to dig them up and store them indoors.
Do I have to wash the tubers before storing them?
While some gardeners simply brush off the dry dirt, washing is highly recommended. Rinsing the tubers allows you to inspect them for rot, insect damage, or hidden pests like slugs. It also makes the "eyes" much easier to see if you plan on dividing the clumps before spring.
What happens if I dig my dahlias before the first frost?
Digging early is possible, but the tubers may not be as mature or hardy. The period after the plant stops blooming but before the frost is when the tubers store the most energy. If you must dig early due to travel or scheduling, try to wait until at least mid-autumn to give the tubers as much time as possible to develop.
My dahlia stems are hollow and have water in them. Is this a problem?
Hollow stems are a natural characteristic of dahlia plants. After cutting and digging, it is important to turn the clumps upside down for 24 to 48 hours. This allows any trapped water to drain out, which is the best way to prevent crown rot during the winter months.
