Table of Contents
- Introduction
- Understanding the Dahlia Life Cycle
- When to Dig Up Your Dahlias
- Tools for a Successful Harvest
- How to Dig Dahlias Without Damage
- Cleaning and Drying the Tubers
- Identifying the Anatomy of a Tuber
- To Divide or Not to Divide?
- Choosing the Right Storage Medium
- Finding the Perfect Storage Location
- Checking Your Tubers During Winter
- Preparing for Spring Planting
- Success Factors for Different Regions
- Troubleshooting Common Issues
- Why Saving Tubers is Worth the Effort
- Conclusion
- FAQ
Introduction
There is nothing quite like the sight of a dahlia garden in full bloom during the late summer months. These plants are the champions of the garden, producing flowers in every color and shape imaginable. At Longfield Gardens, we know that once you fall in love with a specific variety, you want to see it return to your garden every summer. If you're planning ahead, browse our dahlia collections. Saving your tubers—often called bulbs—is a rewarding way to build your collection and enjoy even more flowers each season.
This guide is designed for home gardeners who want to keep their favorite plants healthy through the winter months. We will cover everything from the right time to dig to the best ways to store them until spring. You do not need to be an expert to succeed with this process. With a few simple steps and a bit of patience, you can ensure your dahlias are ready to grow again when the weather warms. Following a clear plan makes overwintering your plants a fun and achievable part of the gardening cycle.
Understanding the Dahlia Life Cycle
Dahlias are tropical plants that grow from underground structures known as dahlia tubers. While many people call them bulbs, they are actually thickened roots that store energy for the plant. In warm climates, these tubers can stay in the ground all year. However, in most parts of the United States, winter temperatures drop low enough to freeze the soil. Because dahlia tubers are full of water, a hard freeze will cause them to turn mushy and perish.
To save your dahlias for next year, you must lift them from the soil and keep them in a protected environment. This process is called overwintering. It allows the plant to stay dormant during the cold months without the risk of freezing. When you save your own tubers, you also get the benefit of a larger harvest. A single tuber planted in the spring will grow into a large clump by the fall. This means your garden can grow bigger and more beautiful every single year.
When to Dig Up Your Dahlias
Timing is the most important factor when learning how to save dahlia bulbs for next year. You want the plant to stay in the ground for as long as possible to maximize energy storage. The tubers grow the most and toughen their skins during the cool weeks of autumn. Waiting for the right signals from nature ensures your tubers are mature enough to survive the long winter in storage. For more timing help, see our guide on when to bring dahlia bulbs in for winter storage.
Watching for the First Frost
In most regions, the signal to start digging is the first "killing frost." This is a night when temperatures drop low enough to turn the green dahlia foliage black or brown. While it might look sad to see your beautiful plants wilt, this is a natural part of their cycle. The frost tells the plant to stop sending energy to the flowers and start storing it in the tubers.
If you live in an area where frost comes very late, you can look at the calendar instead. Most gardeners aim to dig their tubers by mid-November. However, if a hard freeze is predicted that will penetrate the soil several inches deep, you should dig them up immediately. A light frost on the leaves is fine, but frozen soil is the main thing to avoid.
The Curing Period
After the first frost kills the foliage, many gardeners prefer to wait about a week before digging. This short wait is often called "curing" in the ground. During these few days, the "eyes" or growth points on the tubers often become more visible. It also gives the outer skin of the tuber a chance to toughen up. This thicker skin acts like a protective coat during the winter. If your weather is extremely wet, you might choose to dig sooner to prevent the tubers from sitting in soggy soil.
Key Takeaway: Wait for the first frost to turn the foliage black before you begin. This ensures the tubers have stored enough energy and have developed a protective skin for storage.
Tools for a Successful Harvest
You do not need many specialized tools to save your dahlias. Having the right basic equipment on hand will make the job much easier and prevent accidental damage to the tubers.
- A tined garden fork: This is usually better than a shovel. A fork allows soil to fall through the prongs and is less likely to slice through a tuber.
- Pruning shears: You will need these to cut back the heavy stalks.
- A garden hose with a spray nozzle: This helps wash away the soil so you can see what you are doing.
- Labels and a waterproof marker: This is the most forgotten but important tool. All tubers look similar once they are out of the ground.
- Containers for storage: These can be cardboard boxes, plastic bins, or paper bags.
How to Dig Dahlias Without Damage
Digging up a dahlia clump requires a gentle touch. The necks of the tubers—the thin part where they connect to the main stem—are very fragile. If a neck breaks, the tuber may not be able to sprout next year.
Step-by-Step Digging
- Cut the stalks: Use your shears to cut the plant down to about 4 to 6 inches above the ground. This leaves you a "handle" to grab, but removes the heavy foliage that gets in the way.
- Clear the mulch: Move any straw or wood chips away from the base of the plant so you can see the soil clearly.
- Start wide: Place your garden fork in the soil about 12 inches away from the main stem. This ensures you are outside the "splash zone" where the tubers are growing.
- Loosen the soil: Gently push the fork into the ground and rock it back and forth. Do this all the way around the plant in a circle.
- Lift carefully: Once the soil is loose, slide the fork deep under the center of the clump and lift upward. Use your other hand to support the base of the stems.
- Shake off the excess: Gently shake the clump to remove large chunks of dirt. Do not bang the tubers against the ground or each other, as this can cause bruising.
Cleaning and Drying the Tubers
Once the clumps are out of the ground, they need to be cleaned. Removing the soil is important because dirt can hold moisture and bacteria that lead to rot during the winter.
Washing Techniques
Use a garden hose to wash the remaining soil off the tubers. A medium-pressure spray is usually enough to get into the nooks and crannies. If you have heavy clay soil, you might need to use your fingers to gently rub the dirt away. At this stage, you can also trim off the "mother tuber." This is the original tuber you planted in the spring. It often looks darker, feels woodier, and may show signs of decay. Removing it now helps keep the new, healthy tubers clean.
The Drying Phase
After washing, the tubers need to dry before they go into boxes. Find a spot that is out of direct sunlight and protected from frost, such as a garage or a covered porch. Turn the clumps upside down so any water trapped in the hollow stems can drain out.
Let them dry for 24 to 48 hours. The goal is for the surface of the tubers to feel dry to the touch, but you do not want them to sit out so long that they start to shrivel. If the skin looks wrinkled like a raisin, they have dried for too long.
Identifying the Anatomy of a Tuber
Before you decide to store your dahlias, it helps to know what a "viable" tuber looks like. Not every root on the clump will grow a flower next year. For a closer look at healthy tubers, read Dahlia Tubers: What You Need to Know. For a dahlia tuber to be successful, it must have three specific parts:
- The Body: This is the thick, potato-like part that holds the food and energy.
- The Neck: This is the narrow strip that connects the body to the stem. It must be firm and unbroken.
- The Eye: This is the growth point where the new sprout will emerge. Eyes are located on the "crown," which is the knobby area where the neck meets the old stem.
If a tuber breaks off without a piece of the crown attached, it will not have an eye. While that tuber might stay firm all winter, it will never grow a plant. It is often compared to a blind potato; it has energy, but no way to start growing.
To Divide or Not to Divide?
One of the biggest questions gardeners ask is whether they should divide the clumps in the fall or wait until spring. Both methods work well, and the choice depends on your preference and available space. For more on how clumps expand, see Do Dahlia Bulbs Multiply?.
Dividing in the Fall
Many people like to divide their dahlias in the autumn because the tubers are softer and easier to cut. Dividing now also saves space, as individual tubers take up much less room than large, bulky clumps. The challenge is that the "eyes" can be very hard to see in the fall. They often look like tiny, flat bumps that are easy to miss.
Dividing in the Spring
Waiting until spring is a great option for beginners. After a few months of storage, the eyes often begin to swell or even sprout. This makes it very obvious where to make your cuts. The downside is that the tubers become much tougher and woodier over the winter, making them harder to slice through.
Regardless of when you divide, always use a clean, sharp knife. Many gardeners dip their blades in a simple solution of water and a little bleach between plants to keep everything sanitary.
What to do next:
- Decide if you have enough storage space for whole clumps.
- If space is tight, plan to divide your tubers into individual pieces.
- Label every piece immediately with the variety name using a waterproof marker.
Choosing the Right Storage Medium
Storage is the most critical part of saving your dahlias. At Longfield Gardens, we recommend a "Goldilocks" approach: the environment shouldn't be too wet, or the tubers will rot. It shouldn't be too dry, or they will shrivel up. You want to find the perfect middle ground.
Popular Storage Materials
The goal of a storage medium is to insulate the tubers and regulate moisture. Here are the most common materials used by successful gardeners:
- Vermiculite: This is a mineral that holds a small amount of moisture but allows for great air circulation. It is a favorite among professional growers.
- Peat Moss: This is widely available and very lightweight. It should be slightly damp—just enough so that it doesn't feel dusty, but not wet enough to squeeze water out.
- Pine Shavings: Often sold as animal bedding, these are inexpensive and provide good insulation.
- Newspaper: Wrapping individual tubers in several layers of dry newspaper is a simple, low-cost method that works well in humid basements.
The Container Matters
You can store your prepared tubers in cardboard boxes, wooden crates, or plastic bins. If you use plastic bins, do not snap the lid on tight. Tubers are living things that need to breathe. Leaving the lid slightly ajar or drilling a few small holes in the sides of the bin allows for necessary air exchange.
Finding the Perfect Storage Location
Where you put your boxes is just as important as what is inside them. Most homes have a spot that will work, but you may need to test a few areas with a thermometer. If you're unsure about your climate, our Hardiness Zone Map can help.
The Ideal Temperature
The "sweet spot" for dahlia storage is between 40°F and 50°F. If the temperature stays in this range, the tubers will remain dormant. If it gets too warm (above 55°F), the tubers may try to sprout too early or may dry out quickly. If it drops below 32°F, the tubers will freeze and die.
Common successful storage spots include:
- An unheated basement or crawl space.
- An insulated garage that stays above freezing.
- A cool closet in a mudroom.
Avoid storing tubers near a furnace, water heater, or on a high shelf where warm air collects. Also, keep them away from fruit like apples or pears. These fruits give off ethylene gas as they ripen, which can cause tubers to rot or sprout prematurely.
Checking Your Tubers During Winter
Saving dahlias is not a "set it and forget it" task. You should check on your tubers about once a month throughout the winter. This allows you to catch small problems before they ruin your entire collection.
What to Look For
When you open your boxes, look for two main things: rot and shriveling.
If you see a tuber that has turned soft, mushy, or smells bad, remove it immediately. Rot can spread quickly to healthy tubers nearby. If only a small part of a tuber is soft, you can sometimes cut that part away with a clean knife and let the cut surface air dry before putting it back.
If the tubers look very wrinkled or feel light and hollow, they are losing too much moisture. You can fix this by lightly misting the storage medium with a spray bottle of water. You only want to add a tiny bit of moisture—enough to stop the drying process, but not enough to make the medium wet.
Preparing for Spring Planting
As the days get longer and the ground begins to thaw, your dahlias will start to wake up. By late March or April, you may see small sprouts beginning to grow from the eyes. This is an exciting sign that your hard work has paid off! For step-by-step planting help, see When is the Best Time to Plant Dahlia Bulbs?.
Waking Them Up
A few weeks before your last frost date, you can move your storage boxes to a slightly warmer area. This encourages the eyes to "push" and become more visible. If you didn't divide your tubers in the fall, now is the time to do it.
Check your local weather and soil conditions. We recommend waiting to plant your dahlias outdoors until the soil has warmed to about 60°F and the danger of frost has passed. Planting too early into cold, wet soil can cause the tubers to rot before they have a chance to grow.
Success Factors for Different Regions
Your strategy for saving dahlias might change slightly depending on where you live. Gardening is always a conversation with your local climate. If you're not sure where you fit, What Zone Do Dahlias Grow In? is a helpful guide.
Cold Climates (Zones 3-6)
In these areas, the ground freezes deep and stays frozen for months. Digging is mandatory. Focus on finding a storage spot that is well-insulated. An interior basement wall is often the safest place to avoid accidental freezing.
Moderate Climates (Zone 7)
In Zone 7, dahlias are right on the edge. In a mild winter with well-draining soil, they might survive in the ground if they are covered with a thick layer of mulch. However, most gardeners in this zone still choose to dig them up to be safe, especially if they have a favorite variety they don't want to lose.
Warm Climates (Zones 8-10)
In the South and along the West Coast, you can often leave your dahlias in the ground all year. Instead of digging, you simply cut the stems back and cover the area with mulch to protect the crowns from heavy winter rains. However, dahlia clumps can become very crowded after a few years. It is a good idea to dig and divide them every two or three years to keep the plants healthy and productive.
Troubleshooting Common Issues
Even experienced gardeners run into challenges when overwintering plants. Most issues have simple solutions that involve adjusting your storage environment. If you want broader growing help, Are Dahlias Hard to Grow? covers the basics.
Mold on the Surface
If you see a light dusting of white mold on the skins of your tubers, your storage medium is likely too damp. Remove the tubers from the box and let them air dry for a few hours. Replace the damp medium with fresh, dry material and ensure your container has better ventilation.
Stem Rot
Sometimes the hollow stem of the dahlia can trap water and start to decay. This rot can travel down into the crown and ruin the eyes. To prevent this, always store your clumps upside down during the initial drying phase. When you pack them away, make sure the stems are trimmed short and appear dry.
Early Sprouting
If your tubers start growing long, pale sprouts in January or February, they are likely too warm. Move the boxes to a cooler spot. You can snap off these early sprouts if they get too long; the tuber will usually produce a new sprout from the same eye once it is planted in the spring.
Key Takeaway: Consistent monitoring is the best way to ensure success. A quick monthly check allows you to adjust moisture and temperature before problems arise.
Why Saving Tubers is Worth the Effort
While you can certainly buy new dahlias every year, there is a special satisfaction in seeing your own plants return. Saving tubers allows you to:
- Grow your collection for free: One tuber can become five or ten in a single season. If you want a big-blooming collection, try Dahlia Dinnerplate Cloud Nine Collection.
- Share with friends: Extra tubers make wonderful gifts for neighbors and fellow gardeners. A warm-toned option is Dahlia Assorted Sedona Collection.
- Ensure variety: Some rare or heirloom dahlias can be hard to find every year. For a dramatic statement, see Dahlia Dinnerplate Islander.
- Better performance: Often, a dahlia that has "acclimated" to your garden's soil and sun will grow even stronger in its second and third years. For a bouquet-friendly smaller bloom, browse PomPon dahlias.
At Longfield Gardens, we want every gardener to feel the joy of a successful dahlia season. Whether you are growing dinnerplate varieties like Cafe Au Lait or cheerful pompons, the process of saving them for next year is a simple way to extend the beauty of your garden.
Conclusion
Saving dahlia tubers is one of the most rewarding skills a gardener can learn. It turns a one-season flower into a lifetime investment. By following the natural cues of the first frost, cleaning your tubers carefully, and providing a cool, stable storage environment, you can enjoy a spectacular display year after year. Remember that gardening is a learning process, and each season you will get better at identifying eyes and managing moisture levels.
We are here to support you in creating the most beautiful garden possible, and our 100% Quality Guarantee is there if you ever need it. With the right care, your dahlias will be the stars of your summer landscape for many seasons to come.
- Wait for a killing frost before digging.
- Store tubers between 40°F and 50°F in a breathable container.
- Check monthly for signs of rot or shriveling.
- Plant in spring once the soil is warm and the danger of frost is gone.
"Saving your dahlias is like preserving a piece of summer to enjoy again next year. It is a simple act of stewardship that yields a more abundant and beautiful garden with every passing season."
Ready to expand your garden? Explore our planning guides and variety spotlights to find the perfect companions for your saved dahlias next spring.
FAQ
Can I leave my dahlia bulbs in the ground all winter?
This depends on your USDA hardiness zone. If you live in Zone 8 or warmer, you can usually leave them in the ground with a thick layer of mulch for protection. In Zones 7 and colder, the ground will freeze deep enough to kill the tubers, so digging them up is the best way to ensure they survive.
What is the best thing to pack dahlia tubers in for winter?
Most gardeners find success using vermiculite, slightly damp peat moss, or wood shavings. These materials provide insulation while allowing the tubers to breathe. The goal is to keep them from drying out completely without making them so wet that they rot.
My dahlia tubers are shriveled in storage. Are they dead?
Not necessarily! If they are just slightly wrinkled, they are likely just thirsty. Lightly mist the storage medium with water to rehydrate them. If the tuber is completely dry, brittle, and snaps like a twig, it is likely too far gone to grow.
Do I have to wash the dirt off before storing them?
While some gardeners store their tubers with the soil still attached, we recommend washing them. Soil can hide pests and hold moisture that promotes rot. Cleaning them also makes it much easier to see the "eyes" and check the health of the tuber necks.