Table of Contents
- Introduction
- Understanding the Dahlia Life Cycle
- Timing Your Harvest: The First Frost Signal
- Step 1: Cutting Back the Stalks
- Step 2: Digging the Tubers with Care
- Step 3: Cleaning and Rinsing
- Step 4: The Curing Phase
- To Divide or Not to Divide?
- Anatomical Check: What Makes a Viable Tuber?
- Labeling Your Collection
- Choosing Your Storage Medium
- Finding the Perfect Storage Spot
- Managing Moisture During the Winter
- Safety and Practical Precautions
- Preparing for Spring Replanting
- Conclusion
- FAQ
Introduction
Walking through a garden filled with blooming dahlias is a highlight of the summer season. These spectacular flowers offer an incredible range of colors and shapes, from the massive "dinnerplate" varieties like Cafe au Lait to the perfectly symmetrical pompons. Because dahlias are native to the warm climates of Mexico and Central America, they treat our summers like a tropical vacation. However, when the cold air of autumn arrives, these tender plants need a little help to make it through the winter.
Learning how do you save dahlia bulbs—which are technically known as tubers—is one of the most rewarding skills a gardener can master. At Longfield Gardens, we believe that saving your favorite tubers is a wonderful way to expand your garden year after year. It allows you to build a personal dinnerplate dahlia collection without starting from scratch every spring. The process is straightforward and fits into the natural rhythm of the changing seasons.
This guide will walk you through the entire process of lifting, cleaning, and storing your dahlias. We will cover the best timing for digging, how to identify the "eyes" of the tuber, and the best ways to keep them healthy until spring. For a broader overview, see our All About Dahlias guide. Whether you are a beginner or a seasoned grower, these steps will help you protect your investment and ensure a beautiful display next summer. With just a few simple tools and a little bit of space in a cool corner of your home, you can keep your dahlias thriving for many years to bloom.
Understanding the Dahlia Life Cycle
Before you grab your shovel, it helps to understand what is happening beneath the soil. While we often call them bulbs, dahlias grow from tuberous roots. These tubers act as a storage system for the plant. If you're not sure what zone you garden in, check the Hardiness Zone Map. Throughout the summer, the dahlia uses its green leaves to turn sunlight into energy. It stores that energy in the tubers to survive the winter and sprout again when the ground warms up.
In most parts of the United States, the ground freezes deep enough to damage these water-rich tubers. If left in the soil in colder regions, the water inside the tuber will freeze, expand, and turn the root into mush. Saving them is simply the process of moving that storage system to a place where it stays cool but never freezes. It is a simple cycle of rest and regrowth that mimics the plant's natural habitat.
Timing Your Harvest: The First Frost Signal
Timing is the most important factor when learning how to save dahlia bulbs. You want to give the plant as much time as possible to store energy. In late summer and early fall, dahlias are often at their peak, producing dozens of flowers. It can be tempting to dig them up while they look beautiful, but patience leads to better results.
The best signal to start the process is the first "killing frost." This happens when temperatures drop low enough to turn the green foliage black or brown. While the top of the plant looks dead, the tubers underground are perfectly safe. This sudden cold snap tells the plant to shift all its remaining energy down into the roots.
Wait about five to seven days after the first frost before you begin digging. This short waiting period allows the tubers to "cure" slightly while still in the ground. Their skins will toughen up, making them less likely to get damaged during the move. If you live in an area where frost comes very late, you can simply wait until mid-November to start the process. For a step-by-step visual, see How to Lift and Store Dahlia Bulbs.
Step 1: Cutting Back the Stalks
Once the foliage has turned brown, your first task is to clear away the top of the plant. Use a sharp pair of bypass pruners or loppers to cut the main stem. Leave a "handle" of about 4 to 6 inches of stem sticking out of the ground. This handle makes it much easier to move the clump without putting pressure on the fragile tubers.
Dahlia stems are hollow, so you might see water sitting inside the cut stem. This is normal. Be careful not to pull on the stems too hard, as the "neck" where the tuber connects to the stalk is very thin. If the neck breaks, the tuber may not be able to sprout next year.
What to do next:
- Locate your garden pruners and make sure they are sharp and clean.
- Cut all dahlia stalks down to about 5 inches.
- Clear away the dead foliage and add it to your compost pile if the plants were healthy.
Step 2: Digging the Tubers with Care
Now it is time to lift the tubers from their summer home. For this job, a garden fork is much better than a shovel. A shovel can easily slice through a tuber, while the tines of a fork are more likely to slide around them.
Start by placing your fork about 12 inches away from the base of the stem. You want to avoid the "splash zone" where the tubers have expanded. Push the fork deep into the soil and gently pry upward. Move in a circle around the plant, loosening the soil from all sides.
Once the soil is loose, place one hand on the stem handle and use the fork to lift the entire clump out of the ground. It is often surprising how much a single tuber can grow in one season. A small tuber planted in May can turn into a clump the size of a basketball by October. Gently shake the clump to remove large chunks of soil.
Step 3: Cleaning and Rinsing
There are two schools of thought on cleaning dahlias: washing them with water or brushing them dry. The best choice often depends on your soil type. If you have sandy soil, the dirt will likely fall right off once it dries. If you have heavy clay, you may need to use a garden hose.
Use a gentle spray of water to rinse away the dirt. You want to see the "crown" of the plant clearly. This is the area where the tubers meet the main stem. Cleaning them now helps you spot any signs of damage or rot. It also makes it easier to find the "eyes," which are the small bumps that will become next year's sprouts. For a deeper look at the anatomy, see Dahlia Tubers: What You Need to Know.
After washing, turn the clumps upside down. This allows any water trapped in the hollow stems to drain out. If water stays in the stems, it can cause the crown to rot during winter storage. Let them sit in a shaded, protected area for a few hours to dry.
Step 4: The Curing Phase
Curing is a short drying period that helps the tubers prepare for dormancy. After cleaning, place your dahlia clumps in a cool, dry place out of direct sunlight. A garage, shed, or covered porch works well. Do not leave them outside if there is a risk of a hard freeze.
Avoid placing tubers directly on a concrete floor, as concrete can pull moisture out of the roots too quickly. Instead, lay them on a piece of cardboard, a wooden pallet, or a bed of newspaper. Let them dry for 1 to 3 days. The goal is for the outside skin to feel dry and firm, but the tuber itself should still feel heavy and plump.
To Divide or Not to Divide?
One of the most common questions is whether to cut the clumps into individual tubers in the fall or wait until spring. Both methods work well, and the choice is up to you.
Dividing in the Fall
Some gardeners prefer to divide in the fall because the tubers are softer and easier to cut. It also takes up much less storage space. However, the "eyes" can be very hard to see in the autumn. If you divide now, you must ensure every piece has a bit of the crown attached. A tuber without a piece of the crown and an eye will never grow.
Waiting Until Spring
Many people find it easier to store the entire clump and divide it in the spring. By March or April, the eyes will begin to swell and turn pink or purple. This makes it very easy to see exactly where to make your cuts. The downside is that whole clumps take up more room and may hold more moisture, which could lead to rot if not monitored.
Anatomical Check: What Makes a Viable Tuber?
As you handle your dahlias, look for three specific parts. Think of it like a body. The "body" is the fat part of the tuber that holds the energy. The "neck" is the narrow part that connects the body to the top. The "crown" is the head of the tuber where it joins the main stalk.
For a dahlia to grow next year, it must have an intact neck and a piece of the crown with an eye. If a tuber breaks off and loses its neck, it will not grow, even if the body looks healthy. We often call these "blind" tubers. You can compost any pieces that don't have a clear connection to the crown.
Labeling Your Collection
Nothing is more frustrating than a box of mystery tubers in the spring. Because most tubers look identical once they are out of the ground, labeling is a critical step. There are a few easy ways to keep track of your varieties like Thomas Edison.
Another favorite worth tracking is Labyrinth.
- Indelible Marker: You can write the name of the variety directly on the skin of the dried tuber using a permanent marker or a garden pen.
- Flagging Tape: Tie a piece of colorful survey tape or a plastic tag around the neck of the tuber.
- Mesh Bags: Place each variety in its own mesh bag with a waterproof label tucked inside.
Key Takeaway: Proper labeling is the difference between a planned garden design and a random surprise. Always label your tubers before they go into storage boxes.
Choosing Your Storage Medium
Dahlia tubers need a goldilocks environment: not too wet and not too dry. If they stay too wet, they will rot. If they get too dry, they will shrivel up like raisins. A storage medium helps regulate this moisture. Here are the most popular choices:
Vermiculite
This is a natural mineral that is excellent at holding just the right amount of moisture. It is lightweight and clean, making it a favorite for many dahlia enthusiasts.
Peat Moss
Peat moss is slightly acidic and very good at preventing rot. If you use peat moss, make sure it is just barely damp. If it feels dusty, add a tiny bit of water with a spray bottle.
Cedar Shavings
Pine or cedar shavings (the kind used for animal bedding) are an affordable and effective option. They allow for good air circulation while protecting the tubers from temperature swings.
Plastic Wrap
Some gardeners use the "Saran Wrap method." This involves wrapping individual, clean, dry tubers tightly in plastic kitchen wrap. This method relies on the tuber's own internal moisture to stay plump. It is a great space-saver but requires the tubers to be perfectly clean and dry before wrapping.
Finding the Perfect Storage Spot
Where you put your boxes of tubers is just as important as how you pack them. The ideal temperature for dahlia storage is between 40°F and 50°F.
A cool, dark basement is often the perfect spot. If you do not have a basement, an attached garage that stays above freezing or a cool crawlspace can work. Avoid spots near a furnace or water heater, as the air will be too warm and dry.
If the temperature drops below freezing, the tubers will die. If the temperature stays above 60°F, the tubers may think it is spring and try to sprout too early, which wastes their stored energy. Using a simple indoor/outdoor thermometer can help you monitor the spot you choose.
Managing Moisture During the Winter
Successful storage is not a "set it and forget it" task. At least once a month, you should open your storage containers and check on your dahlias. This quick check-up allows you to catch small issues before they become big problems.
If you notice a tuber is soft, slimy, or has a bad smell, it is likely rotting. Remove it immediately so the rot doesn't spread to its neighbors. If the tubers look shriveled or wrinkled, they are losing too much moisture. Give the storage medium a very light misting of water to help them rehydrate.
Healthy tubers should feel firm to the touch, similar to a fresh potato. A little bit of surface mold is usually not a concern and can be wiped off, but deep soft spots are a sign that the environment might be too damp.
Safety and Practical Precautions
While gardening is a joyful activity, it is important to remember that dahlia tubers are not edible. In fact, they can be toxic to dogs, cats, and horses if eaten. When you are storing your tubers, make sure they are kept in a place where curious pets or small children cannot reach them.
Also, remember that every garden is different. Your soil, your local humidity, and the specific variety of dahlia will all affect how well they store. Don't be discouraged if a few tubers don't make it through the winter. This is a natural part of gardening. Even professional growers expect to lose a small percentage of their stock each year.
Preparing for Spring Replanting
As the days get longer in late March or early April, your saved dahlias will start to wake up. This is the time to bring the boxes out of their cold storage. If you stored them in whole clumps, you can now clearly see the eyes and divide them into smaller pieces.
Many gardeners like to "pre-start" their dahlias indoors in pots about four weeks before the last frost. This gives the plants a head start and leads to earlier blooms in the summer. For a fuller growing checklist for the season ahead, see 8 Tips for Growing Better Dahlias. When the soil in your garden warms up to about 60°F, usually around the same time you plant tomatoes, your saved tubers are ready to go back into the ground.
Conclusion
Saving dahlia tubers is a simple and satisfying way to bridge the gap between gardening seasons. It turns a one-time purchase into a lifelong collection and gives you a deeper connection to the plants in your yard. By following the natural signals of the frost and providing a cool, stable winter home, you can enjoy your favorite flowers year after year.
At Longfield Gardens, we want every gardener to feel confident in their ability to grow and maintain a beautiful landscape. For more shopping options, browse our dahlia collection. Protecting your dahlias over the winter is an easy win that pays off in spectacular summer color.
Next Steps for Success:
- Keep a garden journal to note which varieties stored the best in your home.
- Check your storage area temperature with a thermometer before moving the tubers in.
- Order a Dahlia Dinnerplate Cloud Nine Collection in the winter to complement the ones you have successfully saved.
Before you place a winter order, review our Shipping Information.
If you want extra peace of mind, our 100% Quality Guarantee explains how we stand behind every order.
Whatever your skill level, the cycle of lifting and replanting dahlias is a rewarding journey. Soon enough, those quiet brown tubers will transform back into the vibrant, sun-loving stars of your garden.
FAQ
Can I save dahlia bulbs if they haven't been hit by frost yet?
Yes, you can dig up dahlias before the first frost if you need to finish your garden chores early. However, waiting for the frost allows the tubers to maximize their energy storage and helps the skins toughen up for winter. If you must dig early, try to wait until at least mid-November so the tubers have had enough time to mature fully in the soil.
What should I do if my dahlia tubers look shriveled in mid-winter?
If your tubers look wrinkled like a prune, they are getting too dry. You can save them by lightly misting the storage medium (like the peat moss or wood shavings) with a spray bottle of water. Do not soak them, as too much water will cause rot. The goal is to provide just enough humidity to stop the dehydration process and keep the tubers firm.
Is it better to wash the dirt off or leave it on for storage?
Both methods can be successful depending on your local conditions. Washing the dirt off makes it easier to spot rot and find the "eyes" for dividing, but you must ensure the tubers are completely dry before packing them away. Leaving a bit of dry soil on the tubers can sometimes provide a protective layer, but it may also hide pests or diseases, so a gentle cleaning is generally recommended.
How do I know if a dahlia tuber is dead and should be thrown away?
A dead tuber will usually feel very light and hollow, or it will be soft, mushy, and foul-smelling. If you squeeze the tuber and it collapses or oozes liquid, it has rotted and cannot be saved. If the tuber is firm but simply has a broken neck, it is "blind" and won't sprout, so it should also be discarded to save space in your storage container.