Introduction
Dahlias are the undisputed stars of the late summer garden, offering a spectacular finale of color and texture just as other plants begin to fade. There is a special kind of excitement that comes with seeing those first massive dinnerplate blooms or perfect geometric ball dahlias open in your yard. Because these plants are so rewarding, many gardeners want to save their favorite varieties to enjoy again next year.
At Longfield Gardens, we want to help you preserve that beauty by mastering the art of winter storage. While dahlias are tender perennials that cannot survive freezing ground temperatures in most regions, their tubers are remarkably resilient if handled correctly. Learning how to dry and store dahlia bulbs is a simple skill that ensures your garden remains vibrant year after year.
This guide will walk you through the entire process, from the first frost of autumn to the final tucking away of your tubers for their winter nap. We will cover the best timing for digging, the most effective drying techniques, and the storage environments that keep tubers healthy. With these practical steps, you can confidently protect your investment and look forward to an even bigger display next spring.
Timing Your Harvest
The most important part of storing dahlias is knowing exactly when to start. For the best results, you should let nature give you the signal. Dahlias spend the entire summer growing foliage and flowers, but they spend the autumn months focusing energy downward into their tubers.
Wait for the First Frost
In most parts of the United States, the signal to dig comes after the first killing frost. You will notice your dahlia plants turn from vibrant green to a dark, limp black almost overnight. While this might look a bit sad, it is actually a vital part of the plant's life cycle. This frost tells the plant to stop sending energy to the leaves and instead concentrate sugars in the tubers.
If you live in a region where frost comes very late, you don't have to wait forever. If a killing frost hasn't arrived by mid-November, you can proceed with the harvest anyway. The goal is to get the tubers out of the ground before the soil itself begins to freeze solid.
The Curing Period
Once the foliage has turned black, resist the urge to dig immediately. Many experienced gardeners recommend waiting about a week after the frost before lifting the tubers. This brief period allows the "eyes" or growth points on the tubers to become more prominent, which is very helpful if you plan on dividing them later. It also encourages the skin of the tubers to begin toughening up, which makes them less likely to shrivel during storage.
Key Takeaway: Wait for the first frost to turn the foliage black, then give the tubers about a week in the ground to finish their final stage of development before digging.
Cutting Back the Plants
Before you reach for your shovel, you need to clear the way. Working around several feet of tangled stems and leaves can be difficult and may lead to accidental damage to the tubers below.
Trimming the Stems
Use a clean pair of bypass pruners or loppers to cut the main stalks. You should leave about 4 to 6 inches of stem protruding from the ground. This remaining bit of stem serves two purposes: it acts as a handle for moving the clump and it marks exactly where the center of the tuber mass is located.
Labeling Your Varieties
As soon as the flowers are gone, it is very easy to lose track of which dahlia is which. Before you dig, ensure each plant has a waterproof tag attached to the remaining stem. You can use plastic garden markers or even write the variety name directly on the tuber later with a soft pencil or permanent marker. This simple step prevents the "mystery dahlia" surprise in the spring.
How to Dig Dahlia Tubers Safely
Dahlia tubers are surprisingly fragile, especially at the "neck" where the tuber connects to the main stem. If this neck breaks, the tuber will likely not grow, even if it looks healthy otherwise.
Choose the Right Tools
A garden fork or a pitchfork is usually better than a shovel for this task. Shovels have sharp edges that can easily slice through a tuber hidden underground. A fork allows you to loosen the soil and lift the clump with much less risk of mechanical damage.
The Lifting Technique
To lift the tubers safely, follow these steps:
- Start about 12 inches away from the main stem on all sides.
- Insert your fork vertically into the soil and gently pry upward to loosen the earth.
- Work your way in a full circle around the plant.
- Once the soil is loose, slide the fork deep under the center of the clump.
- Use one hand to steady the "stem handle" and the other to lift the fork.
- Avoid pulling hard on the stem; let the fork do the heavy lifting from underneath.
Once the clump is out of the ground, gently shake off the large chunks of soil. Do not bang the tubers against each other or a hard surface, as this can bruise the delicate skin.
Cleaning and Preparing for Drying
Once the tubers are out of the garden, they need a bit of cleaning. There are two main schools of thought on this, and the best choice often depends on your soil type.
The Washing Method
If you have heavy clay soil, the dirt can become like a hard shell around the tubers as it dries. In this case, it is often best to wash the tubers with a gentle stream of water from a garden hose. Removing the soil helps you see any signs of rot or insect damage early on. It also makes the tubers much cleaner to handle when you bring them indoors.
The Brushing Method
If you are lucky enough to have light, sandy soil, you may not need water at all. Simply let the clumps sit in a dry, shaded area for a few hours. Once the soil has dried slightly, you can usually brush it away with your hands or a soft brush. This avoids introducing extra moisture right before the storage phase.
Trimming and Inspection
Take a moment to inspect your tuber clumps. Use a clean pair of snips to trim away the thin, hair-like feeder roots. These roots will simply rot in storage, so it is better to remove them now. You should also cut away any tubers that look mushy, broken, or diseased.
Key Takeaway: Clean your tubers by washing or brushing depending on your soil type, and always remove the thin feeder roots to prevent rot during the winter months.
How to Dry and Store Dahlia Bulbs
The drying process, often called curing, is the most critical step in preventing rot. If you pack away tubers that are soaking wet, they will almost certainly decay. However, if you dry them too much, they will shrivel and die. Finding the balance is the secret to success.
Where to Dry Your Tubers
Find a location that is cool, dry, and out of direct sunlight. A garage, a covered porch, or a basement work well. Never leave your tubers to dry on a concrete floor, as concrete can pull moisture out of the tubers far too quickly. Instead, lay them on a piece of cardboard, a wooden pallet, or a bed of newspaper.
The Best Way to Position Them
Many gardeners find success by drying their dahlia clumps upside down. By resting them on the cut stems, any water trapped inside the hollow stalks can drain out. This prevents moisture from pooling at the "crown" of the tuber clump, which is a common cause of rot.
How Long to Dry
The drying time depends on your local humidity and temperature. Usually, 24 to 48 hours is sufficient. You want the surface of the tubers to feel dry to the touch and the skin to look slightly matte rather than shiny. If you are storing whole clumps, they might need an extra day compared to individual divided tubers.
To Divide or Not to Divide?
One of the most common questions we hear is whether you should divide your dahlia clumps in the fall or wait until spring. Both methods work well, and the choice often depends on your available storage space.
Dividing in the Fall
Dividing now takes up much less space. Instead of large, bulky clumps, you will have small, individual tubers that can be tucked into boxes easily. It is also easier to cut through the stems while they are still somewhat soft. However, it can be difficult to see the "eyes" (the small bumps where next year's growth will start) immediately after digging.
Dividing in the Spring
If you have plenty of space, storing the whole clump is a great "safety first" approach. The clump protects the individual tubers from drying out too fast. In the spring, the eyes will be much more visible, often beginning to sprout, which makes it very clear where you should make your cuts. We often find that for beginners, waiting until spring leads to a higher success rate.
Choosing Your Storage Medium
Dahlia tubers need a goldilocks environment: not too wet, and not too dry. To achieve this, you need a storage medium that regulates humidity.
Recommended Materials
- Vermiculite: This is widely considered the gold standard. It is sterile, lightweight, and excellent at holding just enough moisture without being "wet."
- Peat Moss: A classic choice that is easy to find. It is slightly acidic, which can help inhibit some fungal growth.
- Pine Shavings: Often sold as pet bedding, these are inexpensive and provide great airflow. Avoid cedar shavings, as the oils can sometimes be too harsh for the tubers.
- Newspaper: If you have very high humidity in your storage area, simply wrapping each tuber in several layers of newspaper can be enough.
The Layering Technique
Select a container that allows for some air exchange. Cardboard boxes, wooden crates, or plastic bins with holes drilled in the sides are all excellent options.
Start by placing a two-inch layer of your chosen storage medium at the bottom of the container. Lay your tubers on top, making sure they do not touch each other. If one tuber starts to rot, you don't want it to spread to its neighbors. Cover that layer with more medium and repeat until the box is full.
The Ideal Storage Environment
Once your tubers are packed, they need a home for the winter. The location you choose will determine whether they stay dormant or start to rot.
Temperature is Everything
The ideal temperature for dahlia storage is between 40°F and 45°F. This is cold enough to keep the tubers dormant but warm enough to prevent freezing.
- If the temperature stays above 50°F, the tubers may try to sprout early or dry out.
- If the temperature drops below 32°F, the water inside the tubers will freeze, turning them into mush when they thaw.
Checking Humidity
Aim for a relative humidity of about 80% to 90%. In most homes, an unheated basement, a root cellar, or an insulated crawlspace fits these requirements perfectly. If you must store them in a garage, make sure it is attached to the house or well-insulated so the temperature doesn't plummet during a cold snap.
What to do next:
- Choose a cool, dark storage spot that stays between 40°F and 45°F.
- Select your storage medium (vermiculite or peat moss).
- Pack tubers in layers, ensuring they do not touch.
- Label the outside of the box with the variety name and date.
Winter Maintenance and Check-ups
Storing dahlia bulbs isn't a "set it and forget it" task. To ensure the highest success rate, you should check on your tubers about once a month throughout the winter.
What to Look For
Open your boxes and feel a few tubers.
- If they feel shriveled: This means your storage medium is too dry. Lightly mist the material with a spray bottle of water. Do not soak it; just add enough moisture to raise the humidity.
- If they feel mushy or smell bad: This is a sign of rot. Immediately remove any affected tubers and throw them away. Check the surrounding tubers to make sure the rot hasn't spread.
- If you see mold: This usually means there isn't enough airflow or the environment is too damp. You may need to leave the lid off the box for a few days or move the tubers to a slightly drier location.
Most problems can be fixed if you catch them early. A quick monthly check takes only a few minutes but can save your entire collection.
Transitioning to Spring
As the days get longer and the weather warms, your dahlias will naturally start to wake up. You may see small sprouts beginning to emerge from the crowns of the tubers. This is an exciting sign that your storage was successful!
Wait until the danger of frost has passed and the soil has warmed to about 60°F before planting them back in the garden. For most US gardeners, this is usually around the same time you would plant tomatoes. If you want a head start, you can pot them up indoors about four weeks before the last frost date.
At Longfield Gardens, we have found that the most successful gardeners are those who keep things simple. Don't overthink the process. Focus on keeping the tubers dry, cool, and frost-free, and you will be rewarded with a spectacular show of blooms summer after summer.
Conclusion
Mastering how to dry and store dahlia bulbs is one of the most rewarding skills a gardener can learn. It allows you to build a collection of your favorite varieties and enjoy bigger, better plants every year. By waiting for the frost, curing the tubers properly, and providing a cool, stable winter home, you are setting the stage for a magnificent garden next season.
- Wait for a killing frost to signal the end of the growing season.
- Lift tubers carefully with a fork to avoid neck damage.
- Dry upside down for 24-48 hours in a cool, shaded spot.
- Store in a medium like vermiculite at 40°F to 45°F.
- Check monthly for shriveling or rot.
Successfully overwintering your dahlias is a bridge between the seasons, turning the end of one year's garden into the foundation for the next.
We take pride in providing high-quality dahlias and stand behind our products with a 100% quality guarantee. If you have questions about your plants or need support as you prepare for winter, our team is always here to help you grow your most beautiful garden yet.
FAQ
Should I wash the dirt off my dahlia tubers before storing them?
Washing is helpful if you have heavy clay soil that is difficult to remove when dry. If your soil is sandy or loose, it is often better to simply brush the dirt off once it dries, as this avoids introducing unnecessary moisture to the tubers right before storage.
What should I do if my dahlia tubers look shriveled in the middle of winter?
Shriveling is a sign that the storage environment is too dry. You can remedy this by lightly misting the storage medium (like peat moss or vermiculite) with a spray bottle. The goal is to add just enough moisture to stop the dehydration without making the tubers wet, which could cause rot.
Can I store dahlia tubers in a refrigerator?
While a refrigerator stays within the correct temperature range, it is usually too dry for dahlias, and the lack of airflow can be an issue. If you use a fridge, you must be very careful to keep the tubers in a sealed container with a moisture-regulating medium and check them frequently for rot or extreme dehydration.
How do I know if a dahlia tuber is rotten or still viable?
A healthy dahlia tuber should feel firm, similar to a potato. If a tuber feels mushy, looks black and slimy, or has a foul odor, it is rotten and should be discarded. If only a small part is soft, you can sometimes cut that section away, let the cut heal for a day, and continue storing the healthy portion.
