Introduction
There is nothing quite like the late-summer glory of a dahlia garden.
From the massive, pillowy blooms of dinnerplate varieties to the intricate, geometric petals of ball dahlias, these plants are the undisputed stars of the autumn landscape. As the season winds down, you can keep the magic alive by saving your favorite tubers to plant again next year.
If you especially love ball dahlias, saving tubers helps preserve those perfect spherical blooms for next year.
At Longfield Gardens, we want to help you enjoy these spectacular flowers season after season. Saving tubers is a rewarding way to expand your dahlia collection and ensure your garden remains a vibrant sea of color. While it might seem like a technical task, the process is straightforward once you understand the basic needs of the plant in our All About Dahlias guide.
This guide will walk you through the essential steps to lift, clean, and cure your dahlias for their winter nap. We will cover the best timing for your region and the most reliable storage methods for a successful spring start. Following these simple steps ensures your dahlia tubers stay healthy and ready to bloom when the warm weather returns.
Understanding the Dahlia Lifecycle
Dahlias are native to the warm climates of Mexico and Central America. Because of their tropical roots, they grow as perennials in warm regions but cannot survive freezing ground temperatures. In most parts of the United States, we treat them as tender perennials that need a little extra care to survive the winter.
The dahlia plant spends the summer gathering energy from the sun. It stores this energy in its tubers, which are thickened underground roots. Think of these tubers as the plant’s personal battery pack. The larger and more mature the tuber becomes, the more energy it has to fuel next year’s growth.
The goal of winter storage is to keep these "batteries" from freezing, rotting, or drying out completely. By mimicking the dormant period they would naturally experience in a frost-free climate, we can keep them viable for many years.
Timing Your Harvest for Success
The most common question gardeners ask is exactly when to start digging. The answer depends heavily on your local weather, but the plants will usually tell you when they are ready. For a quick reference, see our Hardiness Zone Map.
The Role of Frost
For the best results, wait for a killing frost to hit your garden. This is the frost that turns the dahlia’s lush green foliage to black or dark brown. While it might look a bit sad, this is a vital part of the process. When the top of the plant dies back, it sends a final surge of energy down into the tubers, helping them "cure" and toughen their outer skin.
If you live in a region where a hard frost doesn't arrive until very late in the year, you can still dig them up in late autumn. Aim for late October or early November. The tubers need to be in the ground long enough to reach full maturity, even if the leaves haven't turned black yet.
The Waiting Period
After the first frost kills the foliage, many experienced gardeners wait about five to seven days before digging. This short waiting period allows the tubers to firm up. During this time, the "eyes" (the small bumps where next year's sprouts will grow) may become more visible. This makes it much easier if you plan to divide your clumps later on.
Key Takeaway: Waiting for the first frost tells the plant to move its energy into the tubers. This makes them stronger and more likely to survive the winter storage period.
Preparing the Plants for Digging
Once the foliage has turned brown or you have reached your target date, it is time to prepare the clumps for removal. Start by cutting the stalks down. You want to leave about 4 to 6 inches of the main stem protruding from the ground.
These short "handles" serve two purposes. First, they help you identify where the center of the clump is so you don't accidentally stab the tubers with your shovel. Second, they provide a convenient way to lift the clump out of the soil without putting stress on the fragile necks of the tubers.
If your dahlias were labeled during the growing season, keep those labels close. It is very easy to mix up varieties once the flowers are gone. For help planning next year's garden, see our Planning Guide for Dahlias.
Essential Tools for the Job
You do not need a shed full of specialized equipment to prepare your dahlias. A few basic tools will make the work much easier:
- A garden fork: This is often better than a shovel. The tines allow soil to fall through while reducing the risk of slicing into a tuber.
- Pruners or loppers: Use these for cutting through the thick, woody stems.
- A garden hose: A gentle stream of water helps remove stubborn soil.
- Labels and a waterproof marker: Essential for keeping track of your colors and types.
How to Dig Without Damaging Tubers
Dahlia tubers grow in a circular clump around the base of the main stem. The "neck" of each tuber—the narrow part that connects it to the main stalk—is quite fragile. If the neck breaks or gets a deep crack, the tuber may rot or fail to sprout in the spring.
Step-by-Step Digging Process
- Clear the area: Remove any mulch or support stakes from around the plant.
- Give them space: Start your digging about 12 inches away from the main stem. This ensures you are outside the main "reach" of the tuber clump.
- Loosen the soil: Insert your garden fork deep into the ground and gently pry upward. Do this on all four sides of the plant. You want to loosen the entire root ball before you try to lift it.
- Lift gently: Once the soil is loose, use the fork to lift the clump from underneath while holding the stem handle for balance.
- Shake and inspect: Gently shake off the loose clods of dirt. At this stage, do not try to pull the dirt out from between the tubers by hand, as this is when most breakage occurs.
What to do next:
- Clear a workspace in a garage or shed where you can process the clumps.
- Gather your labels and markers to ensure every clump is identified immediately.
- Have a garden hose ready if the soil is heavy or clay-based.
Cleaning and Drying Your Tubers
Once the clumps are out of the ground, they need to be cleaned. There are two schools of thought on this: washing with water or brushing away dry soil. The best method usually depends on your soil type.
The Washing Method
If you have heavy clay soil, it often sticks to the tubers like glue. In this case, using a garden hose is the most effective way to see what you are working with. Use a gentle spray to wash away the mud. Focus on the area where the tubers meet the stem, as this is where rot usually starts.
After washing, it is critical to let the tubers dry thoroughly. Most dahlia stems are hollow. If you store them with water trapped inside the stem, the clump will likely rot from the inside out. Turn the clumps upside down for a few hours to let any trapped water drain out of the stalks.
The Dry Brushing Method
In sandy or loose soil, you might find that the dirt falls away easily. You can let the clumps sit in a dry, shaded area for a few hours until the remaining soil feels crumbly. Then, use your gloved hands or a soft brush to remove the excess. This method keeps the tubers drier from the start, which can be an advantage in humid climates.
Trimming the Extras
Before moving to the storage phase, take a moment to tidy up the clump. Use your pruners to snip off the long, thin "hair" roots. These tiny roots won't help the plant next year and can hold unnecessary moisture. You should also cut away any tubers that were badly damaged during the digging process. A clean cut heals better than a jagged tear.
The Curing Process
Curing is a short period of air-drying that helps the skin of the tuber toughen up. This extra layer of protection prevents the tuber from losing too much moisture over the winter.
Place your cleaned clumps in a cool, dry area with plenty of air circulation. A basement, garage, or covered porch works well, provided the temperature stays above freezing. Avoid placing them in direct sunlight, as this can cause them to shrivel too quickly.
Most tubers only need to cure for 2 to 3 days. When the skin feels slightly leathery and the cut ends of the stems look dry, they are ready to be packed away. Do not leave them out for weeks, or they may become too dehydrated to recover in the spring.
To Divide or Not to Divide?
Many gardeners wonder if they should divide their dahlia clumps in the fall or wait until spring. Both methods have benefits, and the right choice depends on your comfort level. If you want a step-by-step refresher, see our How to Divide Dahlia Tubers guide.
Fall Division
The main advantage of dividing in the fall is that the tubers are much softer and easier to cut. You also save a lot of storage space by only keeping the best tubers. However, the "eyes" can be very difficult to see in the fall. An eye is the small growth point found on the crown (the area where the tuber meets the stem). If a tuber doesn't have an eye, it will never grow a new plant.
Spring Division
Waiting until spring is often easier for beginners. After a few months of storage, the eyes will often start to swell or even sprout small green nubs. This takes the guesswork out of where to cut. The downside is that the tubers become quite woody and tough over the winter, requiring a very sharp knife and a bit more muscle to separate.
Key Takeaway: If you aren't sure where the eyes are, it is perfectly fine to store the entire clump and divide it in the spring. This is often the safest bet for ensuring every piece you plant will actually grow.
Selecting the Right Storage Medium
You cannot simply toss dahlia tubers into a pile and expect them to thrive. They need a "nesting" material that balances moisture levels. The ideal medium keeps the tubers from drying out while also absorbing any excess moisture that could lead to rot.
Popular Storage Materials
- Peat Moss: This is the most common choice. It is naturally acidic, which helps inhibit fungal growth. Use it slightly damp (like a wrung-out sponge) or completely dry if your storage area is naturally humid.
- Vermiculite: This lightweight mineral is excellent at regulating moisture. It is clean and easy to handle, making it a favorite for many indoor gardeners.
- Wood Shavings: Pine or cedar shavings (the kind used for pet bedding) provide excellent air circulation. They are less likely to clump up than peat moss.
- Coarse Sand: This is a traditional method, but it makes the storage containers very heavy. It is best used in very dry basements.
Avoid using plastic bags that are sealed tightly. Tubers are living things; they need to "breathe" even while dormant. If you use plastic bins or bags, make sure to poke several holes in them for ventilation. Cardboard boxes and paper bags are excellent breathable options.
Finding the Perfect Storage Location
The success of your winter storage depends heavily on temperature and humidity. You want a "Goldilocks" environment: not too hot, not too cold, and not too wet. For a deeper look at the ideal temperature range, see What Temp to Store Dahlia Tubers?.
The Ideal Temperature Range
Aim for a consistent temperature between 40°F and 50°F. If the temperature drops below 35°F, you risk the tubers freezing, which will turn them into mush. If the temperature stays above 55°F, the tubers may think it is spring and start to sprout prematurely, or they may simply dry out and shrivel.
Common Storage Spots
- Unheated Basements: These are often the best spots as they stay cool and slightly humid.
- Insulated Garages: A garage that stays above freezing is a good choice. Place the boxes on a shelf rather than the cold concrete floor.
- Root Cellars or Crawl Spaces: These traditional storage areas are designed for keeping vegetables and are usually perfect for dahlias.
What to do next:
- Set up your storage boxes with your chosen medium (peat, shavings, etc.).
- Check your storage area with a thermometer to ensure it stays in the 40–50°F range.
- Nestle the tubers into the material so they aren't touching each other.
Winter Maintenance and Troubleshooting
Storing your dahlias is not a "set it and forget it" task. You should check on your tubers once a month throughout the winter. This allows you to catch any potential problems before they spread to the whole collection.
Checking for Rot
During your monthly check, look for tubers that feel soft, mushy, or smell foul. This is a sign of rot. If you find one, remove it immediately and throw it in the trash. Check the surrounding tubers to make sure the rot hasn't spread. For more on common issues, see Common Dahlia Pests and Diseases. If the storage medium feels very wet, replace it with fresh, dry material.
Checking for Shriveling
If the tubers look wrinkled like a prune or feel very light and airy, they are losing too much moisture. To fix this, lightly mist the storage medium with a spray bottle of water. You don't want it wet—just slightly humid. This will help the tubers plump back up.
Identifying Pests
Occasionally, mice or other small rodents might find your storage boxes. If you see signs of chewing, move your tubers into a more secure container, like a plastic bin with ventilation holes, or move them to a higher shelf.
Preparing for Spring
As the days get longer and the ground begins to thaw, your dahlias will start to wake up. This usually happens in late March or April. You might see small pink or green sprouts emerging from the crowns of the tubers.
This is the perfect time to bring them out of storage. If you stored them as whole clumps, you can now easily see the eyes and divide them. Each division needs at least one healthy tuber, a sturdy neck, and one visible eye.
At Longfield Gardens, we recommend waiting until the soil has warmed to at least 60°F before planting them directly into the garden. For a step-by-step refresher, see How to Plant Dahlias. If you want a head start on the season, you can pot your tubers indoors about 4 to 6 weeks before the last frost date. This gives them a chance to develop a strong root system so they can hit the ground running when summer arrives.
Conclusion
Successfully storing dahlia tubers is one of the most satisfying skills a gardener can learn. It allows you to preserve the specific varieties you love and watch your garden grow more beautiful each year without starting from scratch. By paying attention to timing, ensuring a proper curing period, and choosing a cool, breathable storage spot, you can protect your investment and enjoy a stunning floral display every summer.
Remember that gardening is a continuous learning process. Every season brings different weather and soil conditions, so don't be afraid to adjust your methods. Whether you choose to divide your tubers in the fall or wait for the spring sprouts, the most important step is simply getting them out of the frost and into a safe, dry place.
- Wait for the first frost to ensure the tubers are mature and full of energy.
- Dig carefully with a fork to avoid damaging the fragile necks of the tubers.
- Cure for 2 to 3 days in a cool, shaded area before packing.
- Store in a breathable medium like peat moss at temperatures between 40°F and 50°F.
- Check monthly to manage moisture and remove any signs of rot.
Saving your dahlias is a bridge between the seasons, turning the end of one year's beauty into the promise of the next. We look forward to seeing your garden thrive as you master the art of dahlia care.
For even more inspiration, explore our Dahlia Collections.
Looking for fresh combinations for next season? Browse our New Dahlia Collections.
If you love oversized flowers, shop our big blooms.
FAQ
Can I store dahlias in the refrigerator?
While the temperature in a refrigerator is usually in the correct range, the humidity can be a problem. Most modern refrigerators are very dry, which can cause tubers to shrivel quickly. Additionally, some fruits release gases that can damage dormant tubers. It is usually better to find a cool basement or garage instead.
What happens if I dig my dahlias before the frost?
If you live in a very cold climate and need to dig before the frost to beat a hard freeze, it is perfectly okay. The tubers may be slightly smaller and their skins may be thinner, so they will need extra care during the curing and storage process to ensure they don't dry out.
Do I need to use fungicide before storing?
While some gardeners like to dust their tubers with sulfur or a fungicide powder, it is not strictly necessary for the average home gardener. As long as your tubers are clean, dry, and stored in a well-ventilated medium like peat moss or vermiculite, they should stay healthy on their own.
How do I know if a tuber is dead in the spring?
A healthy tuber should feel firm, similar to a potato. If it is completely shriveled and brittle, or if it has turned into a soft, mushy mess, it is no longer viable. If you aren't sure, pot it up anyway; sometimes a tuber that looks a bit rough can still surprise you with a strong sprout.
