Introduction
There is nothing quite like the late-summer glory of a dahlia garden. These plants are the stars of the show, offering a spectacular range of colors and shapes that last right up until the first frost. While many gardeners treat them as annuals, one of the most rewarding aspects of growing these flowers is realizing that you can keep them for next season.
At Longfield Gardens, we believe that gardening should be both beautiful and sustainable. Saving your dahlia tubers—often called bulbs—is a simple way to expand your garden year after year without starting from scratch. It allows you to preserve your favorite varieties and watch your collection grow as the plants naturally multiply.
This guide will show you exactly how to lift, clean, and store your tubers so they stay healthy and ready for spring. Whether you are a beginner or a seasoned grower, you can master this process with just a few basic steps. Saving your dahlias is not only a great way to save money, it is a satisfying end-of-season ritual that guarantees a head start on next year’s blooms.
Understanding Dahlia Tubers
Before you start digging, it helps to understand what you are working with. While many people ask if they can save dahlia "bulbs," dahlias actually grow from tubers. A tuber is a thickened, underground part of a stem or rhizome that serves as a food reserve for the plant during its dormant period.
Unlike a tulip bulb, which is a complete, self-contained unit, a dahlia tuber is part of a clump. Each viable tuber must be attached to a piece of the previous year's stem, which is where the "eyes" or growth points are located. If a tuber breaks off without a piece of the "crown" (the area where the tuber meets the stem), it won't be able to produce a new plant next year.
The beauty of tubers is their ability to multiply. A single tuber planted in the spring will often produce a large clump by autumn. This means that by saving your dahlias, you aren't just keeping one plant—you are often gaining three or four new ones. It is an exciting way to fill more of your garden beds or share favorite varieties with friends.
Why Saving Your Tubers is Worth the Effort
Saving your tubers is a rewarding practice that connects you more deeply to the rhythm of the seasons. Instead of saying a final goodbye to your favorite flowers when the cold weather arrives, you are simply putting them to bed for a well-deserved rest.
One of the biggest advantages is consistency. When you save a tuber from a plant you loved, you know exactly what to expect next year in terms of height, color, and bloom size. You can plan your garden layout with confidence. Additionally, older, established tubers often produce more vigorous plants with more abundant flowers than newly purchased ones.
It is also an excellent way to protect rare or hard-to-find varieties. If you have a specific dinnerplate dahlia or a unique cactus-flowered variety that performed exceptionally well, keeping it safe over the winter ensures you won't have to hunt for it again next spring.
Key Takeaway Saving dahlia tubers is a simple process that allows you to multiply your garden collection for free while ensuring your favorite flowers return year after year.
Timing Your Harvest for Success
Success in saving dahlias begins with proper timing. While you might be tempted to dig them up as soon as the weather turns chilly, patience is a virtue here. The tubers need time to mature and store energy for their winter dormancy.
The Role of Frost
In most climates, the signal to start the harvest is the first "killing frost." This is when the temperatures drop low enough to turn the dahlia’s lush green foliage into a dark, wilted brown. While it might look a bit sad at first, this is actually a helpful sign from nature.
The frost tells the plant to stop sending energy to the leaves and start focusing entirely on the tubers. Many growers like to wait about a week or two after the first frost before digging. This short waiting period, often called "curing in the ground," helps the eyes on the tubers become more visible and toughens the outer skin, which helps them survive storage.
If Frost is Late
If you live in a region where frost comes very late, you don't have to wait forever. If it’s getting late into November and no frost has arrived, you can manually trigger dormancy. Simply cut the plants down to about six inches above the soil level. Wait about ten days for the tubers to settle, and then proceed with digging. This ensures you get them out of the ground before the soil becomes too soggy or freezes solid.
Step-by-Step Guide to Digging Dahlias
When you are ready to lift your dahlias, the goal is to get the entire clump out of the ground without damaging the fragile necks of the tubers.
Tools You Will Need
- A garden fork or pitchfork (preferred over a shovel)
- Pruning shears or loppers
- Garden gloves
- Labels and a waterproof marker
The Digging Process
- Cut back the stalks: Use your shears to cut the main stem down to about four to six inches. This "handle" makes it easier to see where the plant is, but be careful not to use it to yank the plant out of the ground.
- Loosen the soil: Start digging about 12 inches away from the base of the plant. Dahlias can spread their tubers wider than you might expect. Gently push your garden fork into the soil and pry upward.
- Work your way around: Move in a circle around the plant, loosening the soil on all sides. This prevents you from accidentally slicing through a tuber.
- Lift gently: Once the soil is loose, slide the fork deep under the center of the clump and lift the whole mass upward. Use your hand to support the weight of the clump from underneath rather than pulling on the stem.
What to do next
- Immediately attach a label to the remaining stem handle.
- Shake off the largest chunks of soil while still in the garden.
- Move the clumps to a sheltered area, like a garage or porch, to begin the cleaning process.
Cleaning and Prepping for Storage
Once the tubers are out of the ground, they need a little bit of grooming before they can go into storage. Proper cleaning helps prevent diseases and rot from spreading during the winter months.
To Wash or Not to Wash?
This is a common debate among gardeners. Some prefer to leave the soil on, believing it provides a natural protective layer. However, most experts recommend a gentle cleaning. Washing the tubers allows you to inspect them for damage, pests, or signs of rot.
Use a garden hose with a gentle spray to rinse away the dirt. Avoid using high pressure, as you don't want to nick the skin. If you have heavy clay soil, you may need to use your fingers or a soft brush to help the mud release.
Trimming and Inspection
After washing, take a close look at your clump. Trim away any long, thin "feeder roots" that look like hair. These don't help with next year's growth and can often lead to mold in storage.
You should also look for the "mother tuber"—this is the original tuber you planted in the spring. It is usually darker, more wrinkled, and larger than the new tubers. In many cases, the mother tuber will begin to rot at the end of the season. If it looks soft or shows signs of decay, it is best to carefully remove it and discard it, as rot can spread to the healthy new tubers.
Curing the Tubers
Curing is the process of letting the tubers dry slightly before they are packed away. This isn't about drying them out completely; it's about letting the surface moisture evaporate so they don't get mushy.
Place your cleaned tubers in a cool, dry spot out of direct sunlight. A basement, garage, or covered porch works well. Lay them out on a piece of cardboard or a mesh tray. Let them sit for two to three days. When the skin feels dry to the touch and the cut ends of the stems have calloused over, they are ready for their winter home.
Choosing Your Storage Method
There is no "one size fits all" way to store dahlias. The best method for you depends on your local humidity and the space you have available. Here are the three most successful techniques we recommend at Longfield Gardens.
For additional ideas, see this guide to storing dahlia tubers over winter.
1. The Box and Medium Method
This is the most traditional and reliable method. You place the tubers in a container and surround them with a material that regulates moisture.
- The Container: Use a cardboard box, a plastic bin with some air holes, or a wooden crate.
- The Medium: Peat moss, vermiculite, coarse sand, or wood shavings (the kind used for animal bedding) all work well.
- The Process: Put a two-inch layer of your chosen medium at the bottom. Lay the tubers on top so they aren't touching. Cover them with more medium and repeat the layers until the box is full.
2. The Plastic Bag Method
If you have a very dry storage area, plastic bags can help prevent the tubers from shriveling.
- The Process: Place a few handfuls of slightly damp peat moss or wood shavings into a plastic grocery bag or a large freezer bag. Add your tuber clump.
- Ventilation: Do not seal the bag completely. Leave the top open or poke several holes in the sides to allow for air exchange. This prevents the "greenhouse effect" from causing rot.
3. The Paper Wrap Method
For those with limited space or higher humidity, wrapping individual tubers in newspaper can be very effective.
- The Process: Wrap each tuber or small clump in several layers of newspaper. Place the bundles into a cardboard box. The paper acts as a buffer, absorbing excess moisture if it's too damp, but holding in a bit of humidity if the air gets dry.
Finding the Perfect Winter Environment
The environment where you keep your tubers is just as important as the method you use to pack them. They need a "Goldilocks" environment—not too hot, not too cold, and just the right amount of moisture.
Temperature
The ideal temperature for storing dahlia tubers is between 40°F and 50°F.
- If it's too cold: If the temperature drops below freezing (32°F), the water inside the tubers will freeze, causing the cells to burst. When they thaw, they will turn into a mushy, unusable mess.
- If it's too warm: Temperatures above 50°F may signal to the tuber that it's time to wake up. They might start to sprout prematurely or, more commonly, they will dry out and shrivel because their metabolic rate remains too high.
Unheated basements, crawl spaces, or insulated garages are usually the best spots. Avoid keeping them near a furnace, water heater, or on a high shelf where warm air collects.
Humidity
Dahlias prefer a humidity level of around 80% to 90%. This sounds high, but it simply means the air shouldn't be bone-dry.
If your storage area is very dry, you might need to lightly mist your storage medium with a spray bottle once or twice during the winter. If the area is very damp (like a cellar with a dirt floor), make sure you use breathable containers like cardboard or wooden crates to prevent mold.
Dividing: Now or Later?
One of the most common questions we hear is whether you should divide your clumps into individual tubers in the fall or wait until spring. Both approaches have benefits.
Dividing in the Fall
- Pros: The tubers are softer and easier to cut. It takes up much less storage space. You can easily spot any rot inside the stems.
- Cons: It can be very difficult to see the "eyes" (the small bumps where next year’s growth starts) right after digging. If you cut a tuber and miss the eye, that tuber will never grow.
Dividing in the Spring
- Pros: By spring, the eyes will have begun to swell or even sprout, making it incredibly easy to see exactly where to cut. Whole clumps often store better because they have more mass and are less likely to dry out.
- Cons: The tubers become much tougher and more "woody" over the winter, requiring a very sharp knife or even heavy shears to divide.
Our recommendation: If you are a beginner, wait until spring. It is much more discouraging to lose a tuber to a bad cut in the fall than it is to spend a little extra time cutting through a tough clump in April.
Key Takeaway Whether you divide in fall or spring, ensure every tuber has a piece of the crown and a visible eye to guarantee a successful plant for the next season.
Winter Maintenance: The Check-In
Saving your dahlias isn't a "set it and forget it" task. To ensure a high success rate, you should check on your tubers about once a month. This small effort can save an entire collection.
For more guidance, read how long dahlia tubers can be stored.
What to Look For
When you open your storage boxes, look for two main things: rot and shriveling.
- Signs of Rot: If you see any tubers that are soft, slimy, or smelling bad, remove them immediately. Rot can spread quickly through a box. If only a small part of a tuber is soft, you can sometimes cut the bad part off and dust the remaining healthy part with cinnamon (a natural fungicide) or sulfur dust.
- Signs of Shriveling: If the tubers look like wrinkled raisins, they are losing too much moisture. Give your storage medium a light misting of water. You can also place a damp (not soaking) piece of newspaper over the top of the box to add a little humidity.
Dahlias are surprisingly resilient. A little bit of wrinkling is normal and usually isn't a cause for concern, but they should still feel relatively firm when you give them a gentle squeeze.
Common Myths About Saving Dahlias
There is a lot of advice online, and not all of it is helpful for a beginner. Let’s clear up a few common misconceptions.
- Myth: You must use wax. Some older gardening books suggest dipping tubers in paraffin wax. While this does seal in moisture, it is messy, time-consuming, and can actually trap rot inside the tuber. Modern storage methods are much more effective and easier to manage.
- Myth: Dahlias are "hard" to save. While it takes a little bit of work, the process is straightforward. If you provide a cool, dark, frost-free spot, your success rate will likely be very high.
- Myth: You can't save them in warm climates. If you live in Zone 8 or higher, you may be able to leave your dahlias in the ground year-round. However, if your winters are very wet, the tubers may rot in the soil. Even in warm areas, many gardeners dig and store them to ensure they stay healthy and to make it easier to divide the clumps.
If you are unsure of your growing region, check the Hardiness Zone Map.
Preparing for Spring Replanting
The excitement of saving your tubers comes full circle when spring arrives. About four to six weeks before your last frost date, you can bring your tubers out of storage.
At this point, you will see the eyes clearly. They look like small "pimples" or green sprouts near the neck of the tuber. This is the perfect time to divide your clumps if you didn't do so in the fall.
If your tubers look a little bit dry, you can "wake them up" by placing them in a tray of slightly damp potting soil in a warm room. This encourages them to start pushing out roots and sprouts, giving them a jump start before they even hit the garden soil. Just remember to wait until the ground is warm (at least 60°F) and the danger of frost has passed before planting them outside.
Conclusion
Saving your dahlia tubers is one of the most rewarding skills a gardener can learn. It transforms a seasonal flower into a long-term investment, allowing you to curate a personal collection of blooms that gets better every year. By following these simple steps—waiting for the frost, digging with care, and providing a cool, stable winter home—you can ensure your garden is filled with spectacular color season after season.
At Longfield Gardens, we take pride in providing high-quality dahlias that are ready to perform. Whether you are starting with new tubers or preserving your favorites from last year, the joy of seeing those first green shoots emerge in the spring is what gardening is all about.
- Timing is key: Wait for the first frost to signal dormancy.
- Be gentle: Use a fork to lift clumps and avoid damaging the tuber necks.
- Stay cool: Store your tubers between 40°F and 50°F for the best results.
- Check in: Monthly inspections help you catch and fix moisture issues early.
Ready to expand your collection? Explore our premium dahlia tubers and start planning your most beautiful garden yet.
FAQ
Can you save dahlia bulbs in the ground over winter?
In USDA hardiness zones 8 and warmer, dahlia tubers can often survive the winter in the ground if the soil is well-draining. However, in colder zones (7 and below), the ground will freeze deep enough to kill the tubers, so they must be dug up and stored indoors. Even in warm zones, many gardeners dig them every few years to divide the clumps and prevent overcrowding.
How do you tell if a dahlia tuber is still good after winter?
A healthy tuber should feel firm to the touch, similar to a fresh potato. If the tuber is mushy, slimy, or has a foul odor, it has rotted and should be discarded. If it is extremely shriveled and brittle, it may have dried out too much, though you can try soaking it in water for an hour to see if it rehydrates.
Do you have to wash dahlias before storing them?
While it isn't strictly mandatory, washing the soil off makes it much easier to inspect the tubers for rot, pests, or damage. Removing the soil also gets rid of many soil-borne fungi that could cause problems during storage. If you choose not to wash them, ensure the soil is completely dry before packing them away.
Can you store dahlia tubers in a refrigerator?
It is possible to store dahlia tubers in a refrigerator, but it can be risky. Most refrigerators are kept around 35-38°F, which is slightly colder than the ideal range, and the air is often very dry. If you use a refrigerator, keep the tubers in the crisper drawer in a sealed bag with some peat moss, and never store them near ripening fruits like apples, which release ethylene gas that can damage the tubers.
For more information, see this guide to storing dahlia tubers in a refrigerator.
When you are ready to shop again, browse the full Dahlia Collections for new additions to your garden.
