Introduction
There is nothing quite like the late-summer explosion of dahlia blooms in the garden. These spectacular flowers, with their intricate petals and vibrant colors, are the highlight of the season for many home gardeners. As the weather cools and the first frost approaches, the focus shifts from enjoying those blooms to preserving the "gold" hidden beneath the soil. Saving your dahlia tubers is a rewarding way to ensure your favorite varieties return year after year, allowing your garden to grow even more beautiful with each passing season.
At Longfield Gardens, we want to make the process of overwintering your dahlias as simple and successful as possible. One of the most common questions we hear is whether paper bags are a suitable choice for storage. The good news is that paper bags are a time-tested and effective tool for many gardeners, provided you understand how to use them correctly.
This guide will explain how to use paper bags for dahlia storage, which environments they suit best, and how to prepare your tubers for a healthy winter rest. By following a few straightforward steps, you can feel confident that your tubers will stay firm and viable until it is time to plant again in the spring.
The Short Answer: Can You Use Paper Bags?
The short answer is a resounding yes. You can absolutely store dahlia tubers in paper bags. In fact, many experienced gardeners prefer this method because paper is a "breathable" material. Unlike plastic, which can trap moisture and lead to rot, paper allows for a small amount of air exchange. This helps prevent the buildup of condensation, which is the primary enemy of a dormant tuber.
However, the success of the paper bag method depends heavily on your specific storage environment. Because paper is porous, it does not hold moisture in very well. If your storage area is very dry, the tubers may lose too much moisture and shrivel up. If your storage area is naturally damp, the paper acts as a helpful buffer, absorbing excess humidity from the air before it can settle on the tubers.
Choosing paper bags is an excellent option for gardeners who have a root cellar, a cool basement, or an unheated crawl space. It is a simple, low-cost way to keep your varieties organized and protected during their winter sleep.
When to Choose Paper Bags Over Other Methods
Every home has a different "microclimate" in its storage areas. Understanding yours will help you decide if paper bags are the right fit. Dahlia tubers are happiest when they are kept in a state of dormancy—a deep winter sleep where they aren't growing, but they aren't dying either.
High-Humidity Environments
If you live in a region with high winter humidity or if your basement feels a bit damp, paper bags are your best friend. In these conditions, plastic bags or tightly sealed bins can create a "greenhouse effect," trapping moisture and encouraging mold or fungus. Paper bags allow the tubers to stay dry and "breathe," which significantly reduces the risk of rot.
Organizing Multiple Varieties
Paper bags are also the ultimate organizational tool. If you grow several different dahlia varieties, such as dinnerplate dahlias or petite pompons, you likely want to keep them separated. You can easily write the name of the variety, the color, and the planting height directly on the bag with a marker. This saves you from the frustration of "mystery dahlias" when spring finally arrives.
Space Considerations
If you have a large collection of dahlias, storing them in individual paper bags can be more space-efficient than using many large plastic bins. Bags can be tucked into crates or sturdy cardboard boxes and stacked, as long as there is still some airflow around the containers.
Key Takeaway: Paper bags are ideal for storage areas with moderate to high humidity because they prevent moisture buildup. They are also the easiest way to keep different flower varieties labeled and organized.
Preparing Your Tubers for the Bag
Success in storage begins long before you put the tubers in a bag. Proper preparation ensures the tubers are healthy, clean, and ready for dormancy. This process starts when the garden begins to shut down for the year.
The Timing of the Dig
In most regions, we recommend waiting until after the first "killing frost" to dig up your dahlias. You will know it has happened when the foliage of the plant turns black or dark brown almost overnight. This frost signals the plant to stop sending energy to the leaves and start storing it in the tubers.
After the frost, cut the stalks down to about four to six inches above the ground. If you can, wait about a week before digging. This short waiting period helps the tubers "cure" slightly while still in the ground, which toughens their skin for the winter ahead. If a hard freeze (where the ground itself freezes) is predicted, don't wait—get them out of the ground immediately.
Digging with Care
Dahlia tubers are more fragile than they look. They are often compared to a bunch of carrots or sweet potatoes joined at a central neck. If the "neck" of the tuber breaks, it will not grow next year.
Use a pitchfork or a sturdy garden spade to dig. Start at least 12 inches away from the base of the stalk to avoid accidentally slicing through the tubers. Gently pry the entire clump upward from multiple sides until it lifts easily out of the soil. Do not pull the clump up by the stem, as this can damage the vital "eyes" located near the base of the stalk.
Cleaning and Trimming
Once the clump is out of the ground, gently shake off the loose soil. You can use your fingers or a soft brush to remove larger clumps of dirt. Some gardeners prefer to wash their tubers with a hose, while others prefer to leave a little bit of soil on them. Both ways can work. If you do wash them, it is vital that they are allowed to dry completely before they go into a paper bag.
Trim the remaining stalk down to about an inch or two. If there are any long, thin "rat-tail" roots hanging off the main tubers, you can snip those off with clean garden shears. Most importantly, inspect the clump for any signs of damage. If a tuber is mushy, broken, or looks diseased, remove it now so it doesn't spread rot to the healthy ones.
The Curing Phase
Curing is the process of letting the tubers dry out slightly so their outer skin hardens. Place your cleaned clumps on a piece of cardboard or a mesh screen in a cool, dry place away from direct sunlight. A garage or a porch works well, provided the temperature stays above freezing.
Let them sit for one to three days. You want the surface to feel dry to the touch, but you don't want the tubers to start shriveling. This step is crucial when using paper bags; if you put "wet" tubers into a bag, the paper will get soggy, and the tubers will likely rot.
What to do next:
- Wait for the first frost to blacken the foliage.
- Dig carefully, starting a foot away from the stem.
- Shake off excess soil and trim the stalks to 1-2 inches.
- Allow tubers to air-dry (cure) in a cool spot for 24-72 hours.
For a complete overview of lifting, drying, dividing, and storing, see Longfield Gardens' guide to overwintering dahlias.
How to Pack Dahlias in Paper Bags
Once your tubers are cured and dry, it is time to pack them away. You don't want to just toss them into a bag and hope for the best. A little bit of extra care during the packing phase makes a big difference.
Choosing Your Bags
Standard brown grocery bags or smaller lunch-sized paper bags are perfect. Ensure they are clean and dry. Avoid using bags that have a plastic or waxy lining on the inside, as these defeat the purpose of using breathable paper.
Using Packing Media
While you can put tubers in a bag by themselves, they usually stay much healthier if they are surrounded by a "packing medium." This material helps regulate the moisture levels around the tuber. Common choices include:
- Coarse Vermiculite: This is a mineral that holds a tiny bit of moisture but stays very airy. It is one of the most popular choices for dahlia storage.
- Wood Shavings: The kind sold for pet bedding (like pine or cedar) works well and is very affordable.
- Peat Moss: This is a classic choice, though it can be a bit dusty to work with. Ensure it is slightly damp—like a wrung-out sponge—but not wet.
- Shredded Newspaper: If you don't want to buy special materials, shredded paper is a great, free alternative.
Longfield Gardens also covers recommended dahlia storage containers and packing materials.
The Layering Technique
Start by pouring about two inches of your chosen medium into the bottom of the paper bag. Place a dahlia clump (or several individual tubers, if you have divided them) on top of the layer. Ensure the tubers are not touching each other or the sides of the bag if possible.
Cover the tubers with more packing material until they are completely buried, then add another layer if the bag is large enough. Leave a few inches of space at the top of the bag. Fold the top of the bag over loosely—do not staple or tape it shut, as you want a little bit of air to move in and out.
Labeling Everything
Before you move the bags to their final winter home, use a permanent marker to write the variety name on the outside of the bag. We also recommend adding the date and the color. If you have many bags, you can place them all inside a plastic crate or a cardboard box to keep them organized.
Finding the Perfect Storage Spot
The success of your paper bags depends on where you put them. Dahlias have a "Goldilocks" requirement for temperature: they don't like it too hot, and they certainly don't like it too cold.
The Ideal Temperature
The sweet spot for dahlia storage is between 40°F and 45°F.
- If the temperature stays above 50°F for too long, the tubers may think it is spring and start to sprout prematurely. This uses up their stored energy.
- If the temperature drops below 32°F, the water inside the tubers will freeze. When they thaw, they will turn into mush and will no longer be viable.
Humidity and Airflow
Aim for a storage area with about 80% to 90% humidity. This sounds high, but it is typical for many basements and root cellars. The goal is to keep the air moist enough that the tubers don't dry out, but not so wet that they grow mold.
Keep your bags off the floor, especially if you are storing them on concrete. Concrete can draw moisture out of the bags or, conversely, can become very cold. Placing your bags or crates on a wooden shelf or a pallet is a safer bet.
Monitoring Your Tubers During Winter
Gardening doesn't completely stop in the winter; it just moves indoors. One of the biggest mistakes gardeners make is "setting and forgetting" their stored tubers. We recommend checking on your bags once a month.
What to Look For
When you open a bag for a monthly check, feel a few of the tubers.
- Healthy tubers should feel firm, like a fresh potato.
- Shriveled tubers look like a wrinkled raisin. This means your storage area is too dry. If this happens, you can lightly mist the packing material with a spray bottle of water. Do not soak it; just add a tiny bit of humidity back into the bag.
- Mushy tubers are a sign of rot. If you find one, remove it immediately and throw it away. Check the surrounding tubers to ensure the rot hasn't spread.
Adjusting Your Strategy
If you find that your tubers are consistently shriveling in paper bags, it may mean your home's air is too dry (which is common in houses with forced-air heating). In this case, you might need to place your paper bags inside a plastic bin with the lid left slightly ajar. This "double-layer" approach gives you the breathability of paper with the moisture-retention of plastic.
Key Takeaway: A quick monthly check allows you to catch problems early. A light misting can save shriveled tubers, while removing mushy ones prevents the loss of your entire collection.
For additional guidance on storage temperature and monthly maintenance, read this dahlia overwintering guide.
Dividing Tubers: Fall or Spring?
When you store dahlias in paper bags, you have a choice: store the whole clump as it came out of the ground, or divide it into individual tubers first.
Storing Whole Clumps
Storing the entire clump is the easiest method for beginners. The clump acts as a natural protective unit, and the tubers are less likely to dry out when they are all attached to the main stem. The downside is that whole clumps take up much more space in your paper bags.
Dividing in the Fall
Some gardeners prefer to cut their clumps into individual tubers before storing them. This saves space and allows you to fit more varieties into a single bag. If you choose to divide in the fall, you must ensure each tuber has an "eye." The eye is the small bump or bud where next year's stem will grow.
If you divide in the fall, let the cut ends of the tubers dry and "callous over" for a day before putting them into the packing medium. This prevents soil bacteria from entering the fresh cuts.
Dividing in the Spring
Many people find it easier to divide in the spring. By then, the "eyes" have started to swell and are much easier to see. The tubers may be a bit tougher to cut after a winter in storage, but you are less likely to accidentally throw away a viable tuber.
The dahlia tuber care guide explains how to identify healthy tubers and growth eyes before dividing.
Alternatives to the Paper Bag Method
While paper bags are fantastic, they aren't the only way to save your dahlias. If your paper bag experiment didn't go well last year, or if your storage area is exceptionally dry, you might consider these alternatives.
The Plastic Wrap Method
This method involves wrapping individual, clean tubers tightly in plastic kitchen wrap. This creates a tiny, airtight environment for each tuber, which is excellent for preventing shriveling. However, it requires the tubers to be perfectly clean and dry before wrapping, as any trapped moisture will cause immediate rot.
Plastic Bins with Lids
For very large collections, plastic storage totes are a popular choice. Like the paper bag method, you layer the tubers in a packing medium like vermiculite. To allow for airflow, most gardeners drill a few small holes in the sides of the bin or leave the lid slightly cracked.
Cardboard Boxes
If you don't have paper bags, a simple cardboard box works similarly. You can layer tubers and wood shavings directly in the box. Cardboard is breathable and provides good insulation against minor temperature fluctuations.
Transitioning to Spring
As the days get longer and the ground begins to thaw, your dahlias will naturally start to "wake up." You might notice small green or pink sprouts (the eyes) beginning to grow inside your paper bags. This usually happens in late March or April.
Waking Up the Tubers
When you see signs of growth, you can move your bags to a slightly warmer spot to encourage the eyes to develop further. This is a great time to do a final health check. Any tubers that haven't sprouted or that feel hollow can be discarded.
Pre-Starting Indoors
If you live in a northern climate with a short growing season, you can give your dahlias a head start by planting them in pots indoors about four to six weeks before the last frost. This ensures you get blooms earlier in the summer. If you prefer to keep it simple, you can wait and plant your tubers directly in the garden once the soil has warmed up to about 60°F.
Planting Out
When the danger of frost has passed, your dahlias are ready to go back into the earth. Choose a sunny spot with well-draining soil, and place the tubers about 4 to 6 inches deep with the eyes pointing up. Before you know it, those paper-bag-stored tubers will be transforming into the lush, green plants that bring so much joy to the garden.
For more detail on planting depth for dahlia tubers, review the recommended measurements and planting steps.
Conclusion
Storing dahlia tubers in paper bags is a practical and rewarding way to preserve your garden's beauty. It is a method that celebrates the simplicity of gardening—using basic materials to work in harmony with the plant's natural cycle. Whether you are a seasoned grower or a beginner, the paper bag method offers a reliable way to keep your favorite flowers year after year.
We at Longfield Gardens are proud to support you in every stage of your gardening journey, from the first spring planting to the final fall harvest. By matching your storage method to your home's environment and keeping a watchful eye on your tubers over the winter, you can look forward to a spectacular display of dahlias every summer.
- Choose paper bags if your storage area has moderate to high humidity.
- Cure your tubers for 24–72 hours before packing to prevent rot.
- Use a packing medium like vermiculite or wood shavings to protect the tubers.
- Check monthly to ensure the tubers are firm and healthy.
"Gardening is a cycle of growth and rest. By taking care of your tubers today, you are already planting the seeds for next year's success."
FAQ
Can I reuse the paper bags next year?
Yes, you can reuse the paper bags as long as they are still clean, dry, and free of mold. If a bag became damp or if a tuber rotted inside it during the winter, it is best to discard that bag and start fresh to avoid spreading fungus to your healthy tubers next season.
What if my dahlia tubers feel a little soft but not mushy?
If a tuber feels slightly flexible or soft like a soft carrot, it is likely just a bit dehydrated. You can try to save it by misting your packing medium with water or wrapping the tuber in a damp paper towel for 24 hours to see if it firms up. If it is truly mushy or leaks liquid when squeezed, it has rotted and should be thrown away.
Should I wash the soil off completely before putting them in paper bags?
It is a matter of personal preference. Leaving a small amount of dry soil on the tubers can actually help protect them from drying out too quickly. However, washing them makes it much easier to see the "eyes" and spot any signs of rot or damage. If you do wash them, the most important thing is ensuring they are 100% dry before they go into the bag.
Can I store different colors of dahlias in the same paper bag?
You can certainly store multiple tubers in one bag, but if you want to know which color is which next year, it is best to keep them separate or label each tuber individually. You can write the variety name directly on the skin of a dry tuber with a permanent marker before placing it in the bag.
