Introduction
There is nothing quite like the sight of a dahlia garden in full bloom during the late summer months. Whether you enjoy the massive, dinnerplate dahlias or the intricate, honeycomb patterns of pompon varieties, these flowers are often the crown jewels of the backyard. As the days grow shorter and the first touch of frost nears, many gardeners wonder how to protect that investment for next year. While dahlias are tender perennials that cannot survive freezing ground temperatures, saving them is a straightforward and rewarding part of the gardening cycle.
At Longfield Gardens, we want to help you enjoy these spectacular blooms season after season. Whether you grow dinnerplates or pompon dahlias, learning how do you keep dahlia bulbs over the winter is a simple skill that allows you to grow your collection without starting from scratch every spring. By following a few basic steps to lift, clean, and store your tubers, you can ensure they remain healthy and ready to sprout when the warm weather returns. This guide will walk you through the entire process, from the first frost to the final winter checkup.
Knowing When to Bring Your Dahlias Indoors
The first step in overwintering is understanding the needs of the plant. Dahlias are native to the warm climates of Mexico and Central America. Because of this, they are not "winter-hardy" in most parts of the United States. In the gardening world, we use USDA hardiness zones to determine which plants can survive the winter outside. If you live in Zone 8 or warmer, you may be able to leave your dahlias in the ground with a thick layer of mulch. However, for those in Zone 7 and colder, the ground will freeze deep enough to damage the tubers.
The timing for lifting your dahlias is dictated by the weather rather than a specific date on the calendar. We recommend waiting for a "killing frost." This is a night when temperatures drop low enough to turn the dahlia’s green foliage black or brown. While it might be tempting to dig them up as soon as the flowers fade, waiting for this frost is beneficial. The cold snap signals the plant to go dormant and move its remaining energy down into the tubers. This energy storage is what fuels the next year's growth.
If a hard frost is late in arriving, you can still lift your tubers in late autumn. Most gardeners aim to have their dahlias safely tucked away by mid-November. The goal is to get them out of the ground before the soil stays saturated and cold for long periods, which can lead to rot.
A Step-by-Step Guide to Lifting Your Tubers
When you are ready to dig, the process is quite simple, and How to Overwinter Dahlias covers the basics if you'd like a fuller refresher. You will need a few basic tools, such as a pair of sturdy loppers or garden shears and a garden fork. We prefer a garden fork over a shovel because it is less likely to accidentally slice through a tuber.
Start by cutting the stalks down to about four to six inches above the soil line. These short "handles" make it much easier to lift the clumps and keep track of where the tubers are located. Once the stalks are trimmed, move about a foot away from the base of the plant. Carefully insert your garden fork into the soil and gently pry upward. Work your way in a circle around the plant, loosening the soil as you go.
Dahlia tubers grow in a cluster that looks a bit like a bunch of sweet potatoes. These clusters can be surprisingly large and heavy. By prying from all sides, you can lift the entire clump out of the ground without snapping the fragile "necks" of the tubers. The neck is the narrow part that connects the main body of the tuber to the stalk. If this neck is broken, the tuber will not be able to sprout in the spring, so a gentle touch is key here.
What to do next:
- Label each clump immediately after lifting so you don't mix up your varieties.
- Gently shake off the largest clods of soil while you are still in the garden.
- Turn the clumps upside down for an hour to let any trapped water drain out of the hollow stems.
Cleaning and Preparing for Storage
Once your dahlias are out of the ground, they need a bit of cleaning, and Dahlia Tubers: What You Need to Know is a helpful primer before you start. While some gardeners prefer to leave a little soil on the tubers, we find that washing them makes it much easier to spot signs of damage or disease. A gentle stream from a garden hose is usually enough to remove the remaining dirt. Avoid using high-pressure settings, as you do not want to tear the skin of the tubers.
After washing, take a close look at each clump. This is the best time to perform "garden surgery." Use a sharp, clean knife or shears to trim away any thin, hairy feeder roots. You should also look for any tubers that feel soft, mushy, or look shriveled. Removing these "bad apples" now prevents rot from spreading to the healthy tubers during the winter months.
The next phase is arguably the most important: curing. Curing is simply the process of letting the tubers dry out slightly before they are packed away. Place your cleaned dahlias in a cool, shaded area with good air circulation. A garage or a covered porch works well, provided the temperature stays above freezing. Let them dry for two to three days. The skin will toughen up slightly, and the remaining soil will become dust. Do not leave them out for too long, or they will begin to shrivel and lose the moisture they need to survive the winter.
Understanding Tuber Anatomy
Before you pack your dahlias away, it helps to understand what you are looking at. Although many people refer to them as "bulbs," dahlias grow from tubers. For a dahlia tuber to grow into a new plant next year, it must have three specific parts: the body, the neck, and the eye.
The body is the large, swollen part that stores food and energy. The neck is the thin connection point. The eye is a small, slightly raised bump located on the "crown" (the area where the tuber meets the old stalk). This eye is where the new sprout will emerge. If a tuber is detached from the clump but does not have a piece of the crown with an eye, it will never grow, even if the body looks perfectly healthy.
In our trial garden at Longfield Gardens, we often wait until spring to divide our clumps because the eyes are much easier to see once they begin to swell. However, if you are short on storage space, you can divide them in the fall. Just ensure each piece you save has a visible eye and a solid neck. If you are a beginner, keeping the clumps whole is often the safest way to ensure success.
Choosing the Best Storage Medium
The goal of winter storage is to keep the tubers in a "Goldilocks" state: not too wet and not too dry. If they stay too damp, they will rot. If they get too dry, they will shrivel up like raisins and may not have the energy to sprout. To achieve this balance, we use a storage medium.
There are several excellent options for packing your dahlias:
- Peat Moss: This is a classic choice because it holds a tiny bit of moisture but stays loose and airy.
- Vermiculite: This mineral is great for moisture control and is very lightweight.
- Coarse Sand: Sand is effective but can be very heavy if you have a large collection.
- Wood Shavings: Pine or cedar shavings (the kind sold for animal bedding) provide excellent insulation and airflow.
You can store your packed dahlias in various containers. Cardboard boxes, plastic bins with air holes, or even heavy-duty paper bags are all popular choices. We recommend "nesting" the tubers. Place a layer of your chosen medium in the bottom of the container, lay the tubers or clumps on top so they aren't touching each other, and then cover them with more medium. This separation ensures that if one tuber does happen to rot, it won't immediately spoil its neighbors.
Finding the Perfect Winter Home
The location where you store your containers is just as important as how you pack them. Dahlias need a spot that is dark, dry, and cool. The ideal temperature range is between 40°F and 50°F.
An unheated basement, a crawl space, or a cool closet in a mudroom are often perfect spots. If you store them in a garage, make sure the temperature won't drop below freezing during a winter cold snap. A simple way to monitor this is to keep a thermometer near your storage boxes. If the temperature stays consistently above 60°F, the tubers may think it is time to grow and will start to sprout prematurely. If it drops below 32°F, the water inside the tubers will freeze, causing the cells to burst and the tuber to die.
Winter Storage Checklist:
- Keep containers off the floor to prevent moisture wicking.
- Ensure there is some airflow around the boxes.
- Double-check that the area is rodent-proof, as mice sometimes enjoy snacking on tubers.
- Avoid storing near a furnace or water heater.
The Winter Checkup: Ensuring Success
One of the biggest mistakes gardeners make is "planting and forgetting" their tubers in the fall. We suggest checking on your dahlias once a month throughout the winter. This five-minute task can save your entire collection.
Open your containers and feel a few of the tubers. If they feel firm and plump, everything is going perfectly. If you notice a tuber that has become soft or has fuzzy mold growing on it, remove it immediately and throw it away. This prevents the problem from spreading.
If the tubers look shriveled or feel a bit "rubbery," they are losing too much moisture. You can fix this by lightly misting the storage medium with a spray bottle of water. You don't want the medium to be wet—just a tiny bit of humidity is enough to help the tubers plump back up. This simple act of observation allows you to adjust to the unique environment of your home. Every house has different humidity levels, so your dahlias might need a little more or less attention depending on your specific conditions.
Preparing for Spring Planting
As the winter begins to fade and the first signs of spring appear, you can start thinking about getting your dahlias back into the garden. In most regions, this happens in late April or May. The simple rule for planting dahlias is to wait until the soil is warm and there is no longer a danger of frost, and How to Plant Dahlias shows the basics.
About two to four weeks before your last frost date, you can move your containers to a slightly warmer spot to "wake them up." You might see small green sprouts starting to emerge from the eyes. This is an exciting sign that your winter storage was successful. If you kept your clumps whole over the winter, this is the perfect time to divide them if you want more plants. The eyes will be very prominent, making it easy to see where to make your cuts.
When you are ready to plant, Planning Guide for Dahlias can help you choose a sunny spot with soil that drains well. "Drainage" simply means that water doesn't sit in puddles after a rainstorm. Dahlias love sun and food, so adding a bit of compost to the planting hole gives them a great head start. Place the tubers about 4 to 6 inches deep with the sprouts pointing upward.
Why Quality Matters
The success of your dahlia garden starts with the quality of the tubers you begin with. High-quality tubers are more resilient and have a better chance of surviving the dormant season. We work with trusted growers to ensure that every tuber we ship is healthy, true to its variety, and ready to perform in your garden, including our Sunlit Jewel Collection.
We stand behind our quality with a 100% quality guarantee. Our items are true to variety and arrive in prime condition. If you notice any damage or quality issues upon delivery, we encourage you to contact us promptly so we can make it right. If you experience a performance issue during the first growing season, we may provide a replacement or credit depending on the circumstances. Gardening is a journey, and we are here to support you every step of the way.
Shipping and Availability
At Longfield Gardens, we time our shipping based on your specific USDA hardiness zone. We want your tubers to arrive when it is nearly time to plant, typically about two weeks before the ideal planting window for your area. This prevents the tubers from sitting in a box for too long in an environment that might be too warm or too dry, and you can review the details on our Shipping Information.
We ship to the 48 contiguous United States. Because of agricultural regulations, we are unable to ship to Hawaii, Alaska, or US Territories. Additionally, please note that we do not ship allium bulbs to Idaho. Once your order is picked up by the carrier—usually UPS or FedEx—you will receive a tracking number so you can monitor its journey to your doorstep.
Conclusion
Learning how do you keep dahlia bulbs over the winter is one of the most satisfying skills a gardener can master. It turns a one-season display into a lifetime of beauty. By following the natural cycle of the plant—waiting for the frost, lifting with care, and providing a cool, dark winter home—you ensure that your garden will be even more vibrant next year. Visit us at Longfield Gardens to explore our Dahlia Dinnerplate Cloud Nine Collection and start planning your most beautiful garden yet.
- Wait for a killing frost to signal dormancy.
- Lift carefully with a garden fork to protect the "necks."
- Dry for 2–3 days before packing in a medium like peat moss or wood shavings.
- Store in a cool, frost-free place (40–50°F) and check monthly.
Saving your dahlias is a wonderful way to grow your garden and share your favorite varieties with friends and neighbors. We look forward to seeing your garden thrive as you bring these beautiful tubers back to life each spring.
Visit us at Longfield Gardens to explore our latest selection of new dahlias and start planning your most beautiful garden yet.
FAQ
Can I leave my dahlia bulbs in the ground all winter?
This depends entirely on your local climate. If you live in USDA Zone 8 or warmer, you can often leave them in the ground if you provide a thick layer of mulch to protect the soil from freezing. However, in Zone 7 and colder, the tubers will likely freeze and die if left outdoors. If your soil is very heavy or stays wet during the winter, digging them up is always the safer choice to prevent rot.
What is the best temperature for storing dahlia tubers?
The "sweet spot" for dahlia storage is between 40°F and 50°F. This range is cool enough to keep the tubers dormant so they don't sprout too early, but warm enough to ensure they don't freeze. Storing them in an unheated basement, a cool closet, or a crawl space usually provides these conditions. Always use a thermometer to check the temperature of your storage area during the coldest parts of the winter.
Should I wash my dahlias before storing them?
While some gardeners prefer to leave a bit of soil on the tubers, we recommend gently washing them. Cleaning the tubers makes it much easier to inspect them for damage, pests, or rot before they go into storage. Just be sure to let the tubers "cure" or dry in a cool, airy spot for a few days after washing so no surface moisture is trapped in your storage containers.
Why did my dahlia tubers shrivel up during the winter?
Shriveling happens when the storage environment is too dry or the packing medium has no moisture. If the tubers lose too much water, they become "rubbery" and may not have the energy to sprout in the spring. To prevent this, check your tubers monthly and lightly mist the storage medium with water if they look wrinkled. The goal is to keep them plump and firm without making the medium so wet that it causes rot.
