Introduction
As the late summer garden begins to fade, dahlias often provide a spectacular final act. Their vibrant colors and intricate shapes are the highlight of the season, and it is natural to want to see those same blooms again next year. The good news is that you do not have to buy new dahlia tubers every spring. By learning a few simple techniques for lifting and storing them, you can enjoy your favorite varieties year after year.
At Longfield Gardens, we want to make gardening feel rewarding and accessible for everyone. Saving your dahlia tubers is one of the best ways to grow your garden without extra cost. While the process might seem technical at first, it is actually quite straightforward. It involves mimicking the plant's natural dormant cycle and keeping the tubers safe from the winter cold.
This guide will walk you through the entire process, from the first frost of autumn to the first sprouts of spring. We will cover how to dig them up safely, how to store them so they stay plump, and how to check on them during the winter months. With a little bit of care, you can turn a single season of beauty into a lifetime of color.
Why Saving Your Dahlia Tubers Is a Great Idea
Many gardeners treat dahlias as annuals, planting them in the spring and letting them go once the frost hits. While this is certainly an option, saving your tubers offers several benefits. First, it is a fantastic way to save money. High-quality dahlia tubers are an investment, and keeping them alive through the winter means you can spend your garden budget on new varieties instead of replacing old ones.
Second, dahlia clumps actually get larger over time. A single tuber planted in the spring will often produce a large cluster of tubers by autumn. When you save these clumps, you can eventually divide them. This means one plant can become three or four plants the following year. It is an easy way to expand your garden beds or share your favorite flowers with friends and neighbors.
Finally, there is a deep sense of satisfaction in the "circle of life" in the garden. Watching a plant you cared for last year emerge from the soil again feels like a victory. You become more familiar with how the plant grows and what it needs to thrive in your specific soil and climate.
Understanding the Difference Between Bulbs and Tubers
Before we dive into the steps, it is helpful to clarify what we are actually saving. While many people search for "dahlia bulbs," dahlias actually grow from tubers. True bulbs, like tulips or daffodils, are made of fleshy layers (like an onion). Tubers, like dahlias or potatoes, are solid, starchy storage organs.
The distinction matters because of how they grow. A dahlia tuber must have a piece of the "crown" attached to it to grow next year. The crown is the area where the tuber meets the main stem of the plant. This is where the "eyes" or growth buds are located. If you save a tuber but accidentally break it off without a piece of the crown, it will not be able to produce a new plant. Keep this in mind as we discuss the digging and storage process.
When Is the Right Time to Start?
Timing is one of the most important factors when saving dahlias. If you dig them up too early, the tubers may be immature and will likely shrivel during storage. If you wait too long, a deep freeze could reach into the soil and turn the tubers to mush.
In most parts of the country, the ideal time to lift dahlias is after the first frost. You will know the time has come when the lush green foliage turns black or dark brown overnight. This "killing frost" tells the plant to stop growing and move all its energy down into the tubers for the winter.
Many experienced gardeners suggest waiting about a week after that first frost before digging. This short waiting period allows the tubers to "cure" slightly in the ground. It also encourages the "eyes" to become more visible, which makes it easier if you plan to divide the tubers before storing them. However, if your soil is very wet and the weather is consistently rainy, it is better to dig them sooner rather than later to prevent rot.
Step 1: Cutting Back the Foliage
Once the frost has turned your dahlias brown, the first step is to clear away the top growth. Using a sharp pair of garden shears or loppers, cut the main stems down to about 4 to 6 inches above the ground.
Leaving a small "handle" of the stem serves two purposes. First, it gives you something to hold onto while you are digging. Second, it makes it much easier to see where the center of the plant is so you do not accidentally spear the tubers with your shovel.
If the stems are hollow, as dahlia stems often are, some gardeners like to cover the open tops with a little piece of aluminum foil if they are leaving them in the ground for a few days. This prevents rainwater from sitting in the hollow stem and potentially causing rot at the crown.
Step 2: Digging Up the Tuber Clumps
This is the part where most mistakes happen, so take your time. Dahlia tubers grow outward from the center stem in a circular pattern. They can spread surprisingly far, often 12 inches or more in every direction.
The best tool for this job is a garden fork (also called a digging fork). A shovel can work, but a fork is less likely to slice through a tuber. Start by inserting the fork into the soil about a foot away from the main stem. Gently pry upward to loosen the soil. Work your way all the way around the plant in a circle.
Once the soil is loose, gently lift the entire clump from underneath. Do not pull on the stem handle to get it out of the ground. The "neck" where the tuber attaches to the stem is very fragile at this stage. If you pull too hard, the tubers can snap off. Lift from the bottom and let the loose soil fall away.
What to do next:
- Cut stems to 4–6 inches.
- Use a garden fork, not a shovel.
- Start digging at least 12 inches away from the stem.
- Lift the clump from the bottom rather than pulling the stem.
Step 3: Cleaning and Drying
Once the clumps are out of the ground, you need to remove the excess soil. You can gently shake the clump or use your fingers to brush away large chunks of dirt. Some gardeners prefer to wash the tubers with a garden hose. This makes it much easier to see the "eyes" and any signs of damage or rot.
If you do wash them, be gentle. High-pressure water can sometimes nick the skin of the tubers. After washing, turn the clumps upside down so any water trapped in the hollow stems can drain out.
The next step is "curing" or drying. Place the clumps in a cool, shaded area that is protected from frost and direct sun. A garage, shed, or covered porch works well. Let them dry for 1 to 3 days. You want the surface of the tubers to feel dry to the touch, but you do not want them to stay out so long that they begin to shrivel.
Step 4: Labeling Your Varieties
It is nearly impossible to tell dahlia varieties apart once the flowers are gone. A "Cafe au Lait" tuber looks almost identical to a "Thomas Edison" tuber. If you care about which colors go where next year, labeling is essential.
There are a few ways to do this. You can tie a waterproof tag around the stem handle of each clump. Another popular method is to use a soft pencil or a garden marker to write the name of the variety directly on the skin of the larger tubers. Pencil is surprisingly effective because it does not fade or smudge as easily as some ink markers when exposed to moisture.
To Divide or Not to Divide?
One of the most common questions we hear at Longfield Gardens is whether you should divide the dahlia clumps in the fall or wait until the spring. Both methods have advantages.
Dividing in the fall is easier because the tubers are soft. You have more time in the autumn than in the busy spring planting season. It also takes up less storage space because you are only keeping the viable tubers rather than the whole bulky clump.
However, dividing in the spring is often better for beginners. By springtime, the "eyes" (the small bumps that will become next year's stems) are much more prominent. They look like the eyes on a potato. In the fall, these eyes can be very hard to see. If you are new to saving dahlias, we recommend storing the whole clump and dividing it in March or April.
Preparing the Storage Containers
The goal of storage is to keep the tubers in a "dormant but hydrated" state. If they get too wet, they will rot. If they get too dry, they will shrivel up and die. You are looking for a happy medium.
There are several popular storage mediums that help regulate moisture:
- Peat Moss: This is the most common choice. It holds a tiny bit of moisture but stays airy.
- Vermiculite: A mineral that is great for moisture control.
- Wood Shavings: The kind used for pet bedding is inexpensive and effective.
- Coarse Sand: Good for drainage, but very heavy to move around.
Choose a container that allows for some air circulation. Cardboard boxes, plastic crates, or even paper bags work well. If you use plastic bins, do not snap the lid on tight. Leave it cracked or drill a few holes in the sides to prevent stagnant air from causing mold.
The Best Storage Methods
Every gardener has a favorite method, and what works best for you may depend on the humidity in your home or storage area. Here are the three most successful ways to save dahlia tubers.
The Box and Peat Moss Method
Place a layer of peat moss or wood shavings in the bottom of a cardboard box. Lay the dahlia clumps (or individual tubers) on top, making sure they are not touching each other. Covering them with another layer of the medium ensures that if one tuber starts to rot, the problem won't easily spread to its neighbors. Continue layering until the box is full.
The Plastic Bag Method
This is a great space-saver. Place a few handfuls of slightly damp (not wet) peat moss or vermiculite into a plastic grocery bag or a gallon-sized storage bag. Put one or two clumps inside and tie the bag loosely. This method keeps humidity very high, which prevents shriveling, but you must check it frequently for rot.
The Newspaper Wrap
If you have a naturally cool and humid basement, you can simply wrap each clump in several layers of newspaper and tuck them into a crate. The paper provides a small buffer against temperature changes and helps keep the tubers from drying out too fast.
Key Takeaway: The perfect storage setup mimics a "cool basement." You want a medium like peat moss to keep the tubers from drying out, while a breathable container prevents moisture from building up and causing rot.
Finding the Perfect Storage Spot
Location is everything when it comes to overwintering dahlias. The ideal temperature range is between 40°F and 50°F.
If the temperature drops below freezing (32°F), the water inside the tubers will freeze, causing the cell walls to burst. This results in a black, mushy mess that cannot be saved. On the other hand, if the temperature stays above 55°F, the tubers may think it is time to wake up and start growing, or they may simply dry out and shrivel.
Common successful storage spots include:
- An unheated (but attached) garage.
- A cool basement or root cellar.
- A crawl space.
- A closet in a cool part of the house.
Avoid placing your tubers near a furnace, water heater, or on a high shelf in a garage where heat rises. Also, keep them away from drafts or areas where the temperature fluctuates wildly.
Checking Your Tubers Mid-Winter
Saving dahlias is not a "set it and forget it" task. We recommend checking on your tubers about once a month during the winter. This simple habit can save your entire collection.
When you check them, look for two things: rot and shriveling.
If you find a tuber that feels soft, mushy, or has visible mold, remove it immediately. Cut off the rotten part with a clean knife or simply discard that specific tuber so the rot doesn't spread to the rest of the box.
If the tubers look very wrinkled or feel like they are becoming hollow and light, they are too dry. Use a spray bottle to lightly mist the storage medium (the peat moss or shavings) with a little bit of water. Do not soak the tubers; you just want to add a tiny bit of humidity back into the air.
Dealing with Common Problems
Even with the best care, you might run into a few issues. Here is how to handle the most common ones with a positive mindset.
Surface Mold: If you see a little white fuzz on the surface of a tuber, don't panic. This usually means the air is a bit too still. Wipe it off with a cloth dipped in a weak solution of water and a splash of vinegar or bleach. Then, move the container to a spot with slightly better air circulation or leave the lid off for a few days.
Sprouting Early: If you see little green shoots in February, your storage spot is likely too warm. Move the tubers to a cooler location. You can leave the sprouts on; they won't hurt the plant, but you want to slow down its growth until it is actually time to plant.
Shriveled Tubers: If a tuber looks like a raisin, it might still be alive. Soak it in a bucket of lukewarm water for a few hours before planting in the spring. Often, they will plump back up and grow just fine.
When to Replant Your Saved Dahlias
The excitement of spring often makes gardeners want to get their dahlias in the ground as soon as the snow melts. However, dahlias are tropical plants at heart. They love warm soil and hate cold, wet feet.
Wait to plant your saved tubers until the danger of frost has completely passed and the soil has warmed up to about 60°F. In many parts of the country, this is usually around the same time you would plant tomatoes or peppers. For more guidance, see Longfield Gardens' guide to planting dahlias.
If you want to get a head start, you can "wake up" your tubers indoors about 4 to 6 weeks before the last frost. Place them in pots with a little potting soil and keep them in a warm, sunny window. This gives them a head start so you get flowers much earlier in the summer.
Safety for Pets and Children
While gardening is a wonderful family activity, it is important to remember that dahlia tubers can be toxic if eaten by pets. Dogs and cats who dig up or chew on stored tubers may experience digestive upset or skin irritation. Always store your tubers in a secure location where curious pets or small children cannot reach them. If you suspect a pet has ingested part of a dahlia tuber, contact your veterinarian for advice.
Realistic Expectations for Success
It is important to remember that gardening involves living things, and nature can be unpredictable. Even professional growers expect to lose a few tubers during the winter. If you start with ten clumps and eight of them make it through the winter, that is a huge success!
Factors like the humidity in your house, the specific variety of dahlia, and how much energy the plant stored during the summer all play a role. Some varieties are "good keepers" and stay plump no matter what, while others are more finicky. Don't be discouraged if a few don't make it. The ones that do survive will be stronger and ready to put on a show.
Summary of the Saving Process
Saving your dahlias is a simple cycle that follows the seasons. By respecting the plant's need for a dormant period and protecting it from the extremes of winter, you can build a massive collection of flowers over time.
What to do for success:
- Wait for frost: Let the foliage turn black before digging.
- Be gentle: Use a fork to lift clumps and avoid neck damage.
- Label early: Write names on tubers or use waterproof tags.
- Keep it cool: Aim for 40–50°F in a dark, dry place.
- Check monthly: Remove rot and mist if too dry.
Conclusion
Saving dahlia bulbs—or tubers—for next year is a rewarding habit that turns a one-time purchase into a permanent part of your landscape. It allows you to preserve the varieties you love and expand your garden every single year. While it takes a little bit of effort in the late autumn, the sight of those first green sprouts in the spring makes it all worthwhile.
At Longfield Gardens, we believe that everyone can have a beautiful, blooming yard. Whether you are saving a single favorite dahlia or overwintering an entire collection, the process is an investment in the future of your garden. With the right timing, a cool storage spot, and a little bit of patience, you will be well on your way to another season of spectacular blooms.
- Wait for the first frost to signal dormancy.
- Dig carefully to protect the "eyes" and the crown.
- Store in a medium like peat moss to maintain hydration.
- Check your tubers once a month to ensure they stay healthy.
"There is a unique joy in seeing a plant return to your garden year after year. Saving your own tubers is not just about saving money; it is about building a personal connection with your garden that grows stronger with every season."
FAQ
Can I leave my dahlias in the ground over winter?
This depends entirely on your USDA hardiness zone. If you live in Zone 8 or warmer, you can often leave dahlias in the ground if the soil is well-draining. However, in Zone 7 and colder, the ground will freeze deep enough to kill the tubers, so they must be lifted and stored indoors.
Do I need to wash the dirt off the tubers before storing?
It is not strictly necessary, but it is highly recommended. Washing the tubers allows you to inspect them for pests, rot, or damage. It also makes it much easier to find the "eyes" when it comes time to divide the clumps in the spring. Longfield Gardens' overwintering guide covers cleaning, drying, dividing, and storage.
What happens if I dig my dahlias before the frost?
If you dig them too early, the tubers may not have had enough time to store the sugars and starches they need to survive the winter. They are much more likely to shrivel and die in storage. If you must dig early, try to wait until the plants have at least started to yellow.
My tubers look a little moldy in storage, what should I do?
Small amounts of surface mold can be wiped away with a cloth. If the mold is accompanying a soft, mushy spot, that part of the tuber is rotting. Cut away the rot until you see clean, white flesh, or discard the tuber entirely to keep the rest of your collection safe. For a detailed storage reference, see how to store dahlia bulbs over winter.
