Table of Contents
- Introduction
- Timing Your Harvest
- Preparing Dahlias for Digging
- How to Dig Dahlia Tubers Safely
- Cleaning and Inspecting the Clumps
- Dividing Dahlias: Fall vs. Spring
- Curing Tubers for Storage
- Choosing the Right Storage Container
- Creating the Perfect Winter Environment
- Winter Maintenance and Monitoring
- Putting the "How-To" into Practice
- Conclusion
- FAQ
Introduction
Dahlias are the undisputed stars of the late-summer garden, offering a spectacular range of colors and shapes that keep blooming until the very last days of autumn. There is a special kind of satisfaction in watching a single tuber grow into a massive, flower-heavy plant that provides endless bouquets for your home. Because these plants are native to the warm climates of Mexico and Central America, they cannot survive freezing temperatures in most parts of the United States.
At Longfield Gardens, we want to help you enjoy our Dahlia Collections year after year without having to start from scratch every spring. Learning how to dig up and store dahlia bulbs (which are technically tuberous roots) is one of the most rewarding skills a gardener can master. It allows you to multiply your collection and preserve your favorite varieties for the next season.
This guide will walk you through the simple, step-by-step process of harvesting, cleaning, and overwintering your dahlia bulbs. Whether you are a first-time grower or looking to refine your technique, we have the practical tips you need to ensure your dahlias return with vigor. Protecting your investment in your garden is an achievable goal that turns the end of the season into a head start for next year.
Timing Your Harvest
The most common question gardeners ask is exactly when to bring their dahlias indoors. While it can be tempting to dig them up as soon as the weather turns chilly, patience is a significant factor in tuber health. The tubers spend the late summer and early autumn storing energy and toughening their "skin," which helps them survive the long winter months in storage.
For most gardeners in zones 3 through 7, the signal to start digging is the first killing frost. You will know it has happened when the lush green foliage of your dahlias turns black or dark brown overnight. This frost tells the plant to go dormant and move all its remaining energy down into the root system. If you’re not sure where you fall, check our Hardiness Zone Map.
If you live in a region that does not experience a hard frost by mid-November, you can still proceed with the harvest. As long as the plants have had about 120 to 150 days of growth, the tubers should be mature enough to store. In these warmer areas, simply cut the plants back manually to trigger the dormancy process.
Key Takeaway: Wait for the first frost to blacken the foliage before you begin the harvest. This natural signal ensures the tubers are fully mature and ready for their winter rest.
Preparing Dahlias for Digging
Once the frost has arrived and the foliage has wilted, your first step is to cut the plants back. Use a clean, sharp pair of loppers or garden shears to cut the main stalks. You should leave about 4 to 6 inches of the stem protruding from the ground. This "handle" serves two purposes: it makes it easier to lift the clump later, and it helps you keep track of where the tubers are located so you don't accidentally strike them with a shovel.
After cutting the stalks, many experienced gardeners prefer to leave the tubers in the ground for about 5 to 10 days. This short waiting period is often called "curing in the ground." During this time, the "eyes" or growth points on the tubers often become more prominent and easier to see. It also allows the outer skin of the tuber to begin toughening up.
If heavy rain or a deep ground freeze is in the forecast, you can skip this waiting period and dig them up immediately. The most important thing is to get the tubers out of the soil before the ground itself freezes solid, as frozen tubers will rot once they thaw.
What to Do Next:
- Identify which plants are which and ensure labels are secure.
- Cut the stems down to 6 inches above the soil line.
- Gather your tools, including a sturdy garden fork and a hose.
- Check the weather forecast to ensure you have a dry window for digging.
How to Dig Dahlia Tubers Safely
Digging up dahlias requires a gentle touch because the necks of the tubers—the narrow part where the tuber connects to the main stem—are quite fragile. If a tuber snaps off at the neck, it usually loses the "eye" required to grow next year, making that individual piece useless.
Instead of a traditional pointed shovel, we recommend using a large garden fork or pitchfork. A fork allows you to loosen the soil without creating a solid "blade" that might slice through a hidden tuber.
Start by inserting your fork into the soil about 12 inches away from the main stem. It is better to start too far away than too close. Push the fork deep into the ground and gently pry upward to loosen the soil. Work your way in a full circle around the plant, lifting and loosening as you go.
Once the soil is loose all the way around, gently lift the entire clump out of the ground using the stem handle as a guide. Do not pull hard on the stem; if the clump feels stuck, use the fork to loosen the soil further underneath the center of the plant.
Cleaning and Inspecting the Clumps
Once the dahlia clump is out of the ground, you will likely see a large mass of tubers and soil. Shake the clump gently to remove large clods of dirt. If your soil is sandy, most of it will fall away easily. If you have heavy clay soil, you may need to be more hands-on.
Using a garden hose with a gentle spray setting, wash the remaining soil off the tubers. It is important to see the entire structure of the clump so you can inspect it for damage or disease. Clean tubers are also much less likely to harbor soil-borne pests or fungi during winter storage.
While cleaning, look for the following:
- Firmness: Healthy tubers should feel like a firm potato.
- Color: They should have a consistent color without large black or soft spots.
- Damage: Note any tubers that were sliced or broken during digging.
- Rot: If you see any part of the clump that is mushy or smells bad, trim it away immediately with a clean knife.
We recommend rinsing your tools with a simple solution of rubbing alcohol or diluted bleach between different dahlia varieties, especially if you are sorting a mixed collection like the Dahlia Assorted Sunlit Jewel Collection. This prevents the accidental spread of any viruses or bacteria from one plant to another.
Dividing Dahlias: Fall vs. Spring
One of the biggest debates among dahlia enthusiasts is whether to divide the clumps into individual tubers in the fall or wait until the spring. At Longfield Gardens, we believe both methods can be successful, and the right choice depends on your schedule and storage space. For a broader overview, read All About Dahlias.
Dividing in the Fall
Dividing in the fall saves a significant amount of space. Instead of storing a basketball-sized clump of dirt and roots, you only store the individual, viable tubers. The main challenge with fall division is that the "eyes" (the small bumps where next year's stems will grow) can be very difficult to see.
If you choose to divide now, look for the eyes near the "crown," which is the area where the tuber meets the stem. Use a sharp, sterilized knife to cut the tubers away, ensuring each piece includes a portion of the crown and at least one eye.
Dividing in the Spring
Many home gardeners find it easier to store the entire clump whole. The extra mass of the clump helps prevent individual tubers from drying out too quickly during the winter. In the spring, after the tubers have been in storage, the eyes will often begin to swell or even sprout, making it incredibly easy to see exactly where to cut.
If you have enough room in your storage area, keeping the clumps whole is the safest "beginner-friendly" method. You can simply brush off the excess soil and store the entire unit.
Key Takeaway: If you aren't sure where the "eyes" are, leave the clump whole until spring. It is better to store the whole clump than to accidentally cut off the growth points.
Curing Tubers for Storage
Before you pack your dahlias away for the winter, they need to "cure." This is a short drying period that allows any surface moisture to evaporate and helps the skin of the tuber to further toughen.
Place your cleaned tubers or clumps in a cool, dry area that is protected from direct sunlight and frost. A garage, shed, or basement is usually ideal. Lay them out on a piece of cardboard, a wooden pallet, or a screen to allow for good airflow.
Do not leave them on a bare concrete floor, as concrete can actually pull moisture out of the tubers too quickly, causing them to shrivel. Most dahlias only need 24 to 48 hours of curing. You want the exterior to be dry to the touch, but you do not want the tubers to start looking wrinkled or shriveled.
If you have cut or divided your tubers, the "wounds" where you made the cuts need to dry and form a callous. This callous acts as a protective barrier against rot.
Choosing the Right Storage Container
The goal of dahlia storage is to keep the tubers dormant, cool, and slightly hydrated. If they get too wet, they will rot; if they get too dry, they will shrivel up and die. The container you choose helps maintain this delicate balance.
There are several effective ways to pack your dahlias:
- Cardboard Boxes: These are breathable and easy to find. Line the box with a few layers of newspaper.
- Plastic Totes: These hold moisture very well. If you use plastic, do not snap the lid shut completely; leave it cracked an inch or two to allow for gas exchange.
- Paper Bags: Great for individual tubers or small clumps, but they offer less protection against temperature swings.
- Plastic Wrap: Some gardeners wrap individual, clean tubers tightly in plastic wrap. This is a specialized technique that works best if your storage area is very consistent in temperature.
Regardless of the container, you should use a packing medium to insulate the tubers. This medium helps regulate humidity and prevents the tubers from touching one another, which stops the spread of rot if one piece happens to go bad. Popular options include slightly damp vermiculite, coarse sawdust, wood shavings (like the kind used for pet bedding), or peat moss.
Creating the Perfect Winter Environment
Location is the most critical factor in successful dahlia storage. You are looking for a "Goldilocks" spot that stays consistently between 40°F and 50°F.
If the temperature drops below freezing (32°F), the water inside the tubers will freeze, expanding and destroying the cell walls. This results in "mush" when they thaw. Conversely, if the temperature stays above 55°F, the tubers may think it is time to grow and will begin to sprout prematurely, exhausting their energy reserves before spring arrives.
Common storage locations include:
- Unheated Basements: Usually provide the most consistent temperature and humidity.
- Attached Garages: Can work well, but you must ensure the tubers are kept away from exterior walls or drafty doors where they might freeze.
- Root Cellars: The traditional choice for a reason—they naturally maintain the ideal cool and damp conditions.
Check the humidity of your storage area. If it is very dry, you may need to use more packing medium or mist the tubers very lightly a few times during the winter. If the area is naturally damp, use a more breathable container like a wooden crate or a cardboard box.
Winter Maintenance and Monitoring
Storing dahlias is not a "set it and forget it" task. To ensure a high success rate, 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.
When you perform your monthly check, look for two things: rot and shriveling.
If you see rot:
Rot usually appears as soft, mushy, or blackened spots. It often has a distinct, unpleasant odor. If you find a tuber that has started to rot, remove it immediately. If the rot is only on a small portion of a large clump, you can sometimes surgery it out with a clean knife, but it is often safer to discard the affected piece entirely to protect the rest of your stock.
If you see shriveling:
If the tubers are starting to look like wrinkled raisins, they are losing too much moisture. This is a sign that your storage medium is too dry or your container is too breathable. To fix this, you can lightly mist the packing medium with water using a spray bottle. You don't want it to be "wet," just slightly damp to the touch. You can also close the lid of your container a bit more to trap the remaining moisture.
Key Takeaway: A quick monthly inspection is the best way to prevent total loss. Catching one "bad apple" early saves the rest of the crate.
Putting the "How-To" into Practice
Dahlias are incredibly resilient plants, and while the storage process has a few specific requirements, it is something any gardener can do. By following these steps, you are participating in a long tradition of seasonal gardening that honors the natural lifecycle of the plant. At Longfield Gardens, we have spent years trialing different dahlia varieties and storage methods, including favorites like Dahlia Dinnerplate Cafe Au Lait.
We know that every garden has its own unique microclimate, and your storage conditions might take a season or two to perfect. Don't be discouraged if a few tubers don't make it through the first year—even professionals expect a small percentage of loss. For another favorite, see our Dahlia Dinnerplate Cloud Nine Collection.
The reward for your effort comes in the spring, when you pull those firm, healthy tubers out of storage and see the first signs of green growth. If you want to add more color to next year’s garden, try Dahlia Dinnerplate Summer Lovin Collection. You’ll have larger plants, more flowers, and the pride of knowing you cared for them through every season.
Next Steps for Success:
- Prepare your storage space: Find a spot in your home that stays between 40°F and 50°F.
- Buy your medium: Pick up a bag of vermiculite or wood shavings before the first frost hits.
- Label clearly: Use a waterproof marker to write the variety name directly on the tuber or a sturdy tag.
- Order new favorites: If you want to expand your collection, browse Dahlia Dinnerplate High Summer Mix to add new colors and shapes to your garden next spring.
Conclusion
Digging and storing dahlia bulbs is a simple way to bring more beauty to your garden year after year. By paying attention to the timing of the first frost, handling the fragile tubers with care, and providing a cool, stable environment for the winter, you can successfully overwinter these spectacular flowers. This process not only saves you money but also allows you to grow massive, mature plants that produce far more blooms than a first-year tuber.
- Wait for the first frost to signal dormancy.
- Dig carefully with a fork to protect the fragile "necks."
- Store in a cool, dark place (40–50°F) in a breathable medium.
- Check monthly for rot or shriveling to ensure health.
We are proud to stand behind the quality of our plants with a 100% quality guarantee, and we are always here to help you troubleshoot your growing season. Whether you are adding new varieties from Longfield Gardens or saving your cherished favorites, we wish you a successful harvest and a vibrant garden next year.
Digging up your dahlias is like tucking your garden in for a long winter nap. With just a little bit of preparation, you’ll be ready to welcome them back for a spectacular show next summer.
FAQ
Can I leave my dahlias in the ground over winter?
This depends entirely on your USDA hardiness zone. If you live in Zone 8 or warmer, you can often leave dahlias in the ground if the soil is well-drained and you apply a thick layer of mulch. However, in Zones 7 and colder, the ground will freeze deep enough to kill the tubers, so digging them up is necessary for survival.
What happens if I dig up my dahlias before the first frost?
You can dig them up early if needed, especially if you have a short growing season or an early winter storm approaching. The main drawback is that the tubers may be smaller and the skin will be thinner, which makes them more prone to shriveling in storage. Try to wait as long as possible to ensure the tubers are mature.
Do I need to wash the dirt off the tubers before storing them?
While some gardeners store their dahlias with the soil still attached, we recommend washing them. Removing the soil allows you to inspect the tubers for rot or pests and prevents soil-borne diseases from lingering in your storage containers. Just be sure to let the tubers dry completely (cure) before packing them away.
My stored tubers are sprouting in February; what should I do?
If your tubers start sprouting early, it usually means your storage area is too warm. Move them to a cooler spot if possible. You can leave the sprouts alone; as long as they stay in a dark, cool place, the growth will remain slow. If the sprouts get very long and spindly, you can gently snap them off, and the tuber will usually produce new "eyes" once planted in the spring.
