Introduction
Few things in the garden are as rewarding as a dahlia in full bloom. Whether you love the massive, intricate petals of dinnerplate dahlias or the cheerful pops of color from smaller pompon types, these flowers are the stars of the late summer landscape. As the growing season winds down, many gardeners look for a simple way to save those beautiful tubers so they can enjoy them again next year.
At Longfield Gardens, our 100% Quality Guarantee and practical advice make overwintering your favorite plants a satisfying part of the gardening cycle rather than a stressful task. While there are many ways to store dahlias, using plastic wrap—often called the Saran Wrap method—is one of the most effective techniques for home gardeners. This method keeps tubers plump and healthy without the need for bulky bins of peat moss or wood shavings.
This guide will walk you through the process of prepping, dividing, and wrapping your tubers to ensure they stay in peak condition until spring. We will cover everything from the right time to dig to the specific way to wrap each piece for maximum protection. By the end of this article, you will have a clear, step-by-step plan for preserving your dahlias with ease.
Why Choose the Plastic Wrap Method?
If you are new to storing dahlias, you might wonder why plastic wrap is such a popular choice among enthusiasts. Traditionally, gardeners stored dahlia tubers in large crates filled with vermiculite, sand, or peat moss. While those methods work, they take up a lot of space and make it difficult to check on the health of your tubers during the winter.
The plastic wrap method offers several unique advantages that make it a "quiet winner" for home storage. First, it is incredibly space-efficient. Instead of large bins, you can store hundreds of tubers in a few small cardboard boxes or even a drawer in a cool basement. Because each tuber is wrapped individually or in small bundles, you can fit a significant number of plants into a very small footprint.
Another benefit is visibility. Since the wrap is clear, you can easily see if a tuber is beginning to sprout or if a rare spot of rot has developed. More importantly, the plastic wrap acts as a barrier. In a traditional bin, if one tuber starts to decay, the moisture and fungus can quickly spread to its neighbors. With the plastic wrap method, each tuber is isolated. If one has an issue, the plastic prevents it from affecting the rest of your collection.
Finally, plastic wrap is excellent at managing moisture. It holds in just enough of the tuber’s natural humidity to prevent it from shriveling like a raisin, but it doesn't trap so much moisture that the tuber becomes waterlogged. This balance is key to keeping the tubers firm and viable for spring planting.
Key Takeaway: Plastic wrap is a space-saving, hygienic, and high-visibility way to store dahlia tubers that helps prevent the spread of rot while keeping the tubers plump.
When to Dig Your Dahlias
Timing is everything when it comes to a successful harvest. You want to give the tubers as much time as possible to mature in the ground, but you must get them out before the soil freezes solid. In most regions, the signal to start digging is the first "blackening" frost.
When a hard frost hits, the foliage of your dahlias will turn from vibrant green to a dark, wilted brown or black. This is a natural part of the plant's life cycle. Once the tops are killed by frost, the plant stops sending energy upward and focuses on "curing" the tubers underground. We recommend waiting about five to seven days after this first frost before you begin digging. This short waiting period allows the tubers to toughen their skins, which makes them more resilient during the storage months.
If you live in a climate where frost comes very late or not at all, you can simply wait until the plants look tired and begin to yellow in late autumn. At that point, you can cut the stalks down and proceed with digging. Just be sure to check your local weather forecast to ensure you aren't digging in a period of heavy, cold rain, which can make the cleaning process much messier than it needs to be.
Identifying Your Varieties
Before you cut the stalks, make sure your plants are labeled. It is very easy to tell a red dahlia from a white one when they are in bloom, but once the stalks are cut, every tuber looks exactly the same. Use waterproof tags or surveyor’s tape to mark the variety name on the lower part of the stem. This small step ensures that when you go to plant your garden next spring, you know exactly where each color and size is going.
How to Dig Without Damage
Dahlia tubers grow in a clump that looks a bit like a bunch of sweet potatoes. These clumps can be surprisingly wide, often extending 12 inches or more from the main stalk. To avoid slicing through the tubers with your shovel, start digging several inches further out than you think you need to.
Using a garden fork is often better than a spade. A fork allows you to loosen the soil around the clump without the "guillotine" effect of a sharp metal blade. Gently insert the fork into the soil around the perimeter of the plant and lift upward. Work your way around the entire clump until it feels loose.
Once the soil is loosened, grab the base of the stalk (the "handle") and gently lift the entire clump out of the ground. Don't worry if some soil clings to the tubers; you will wash that off in the next step. The goal here is to keep the "necks"—the thin part where the tuber connects to the main stem—intact. A tuber with a broken neck is unlikely to grow next year, so handle the clumps with care.
What to Do Next
- Wait for the first frost to turn the foliage brown.
- Leave the tubers in the ground for about a week to cure.
- Label every plant clearly before cutting the stalks.
- Dig a wide circle around the plant to avoid physical damage to the tubers.
Cleaning and Drying the Tubers
Once your tubers are out of the ground, they need a good cleaning. Soil can harbor fungi and bacteria that lead to rot during the winter, so it’s best to store them as clean as possible.
Use a garden hose with a gentle spray nozzle to wash away the dirt. You don't need high pressure; just enough to see the skin of the tubers clearly. Some gardeners like to use a soft brush to get into the nooks and crannies near the crown of the plant. At this stage, you can also trim away any long, thin "rat-tail" roots that extend from the bottom of the tubers. These thin roots won't produce flowers and can often shrivel or rot in storage, so removing them now keeps your bundles tidy.
The Importance of Drying
After washing, your tubers will be wet. This is where many gardeners make a mistake by rushing to wrap them immediately. Storing a soaking wet tuber in plastic wrap is a recipe for mold.
Place your cleaned clumps in a frost-free, shaded area with good airflow. A garage, a covered porch, or a basement floor works well. Lay them out on newspaper or cardboard. Let them dry for at least 24 hours. They should feel dry to the touch and the skin should look slightly duller than when they were freshly washed. If the weather is particularly humid, you might need to give them two days. The goal is to remove surface moisture while keeping the inside of the tuber firm and hydrated.
Anatomy of a Dahlia Tuber
To be successful with the plastic wrap method, you generally need to divide your dahlia clumps. Storing a whole, massive clump in plastic wrap is difficult and often leads to trapped moisture in the center of the clump. Before you start cutting, you need to know what makes a tuber viable.
A dahlia tuber is only "useful" for next year if it contains three specific parts:
- The Body: This is the fat, potato-like part that stores energy and nutrients.
- The Neck: This is the narrow portion that connects the body to the crown. It must remain unbroken and firm.
- The Eye: This is the most critical part. The eye is a small bud, similar to the eye on a potato, located on the crown (where the neck meets the old stalk). This is where the new growth will emerge in the spring.
If you have a fat tuber but it has no eye, it will never grow a plant. If you have an eye but the neck is snapped, the eye won't have any energy to feed on. Keeping these three parts connected is the key to success.
Dividing for Storage
Dividing dahlias in the fall can feel a bit intimidating, but it is actually easier than doing it in the spring. In the fall, the tubers are softer and easier to cut. We use sharp, sterilized bypass pruners or a clean kitchen knife to make the cuts.
Start by cutting the main stalk down as close to the crown as possible. Then, look for the eyes. They often look like tiny, raised bumps or "pimples" on the crown. If you can't see them yet, don't worry—some varieties are slower to show their eyes than others. If you are unsure, you can simply cut the clump into smaller sections, ensuring each section has a piece of the old stem attached.
As you divide, discard any tubers that feel mushy, hollow, or significantly damaged. If you accidentally nick a tuber while cutting, it’s usually okay. The cut will callous over. However, if the neck is floppy or broken, that specific tuber can be composted.
The Wrapping Process: Step-by-Step
Now that your tubers are clean, dry, and divided, it is time for the main event: wrapping them in plastic. You can use any standard brand of clear plastic wrap from the grocery store.
Step 1: Prepare the Wrap
Tear off a piece of plastic wrap about 15 to 20 inches long. Lay it flat on a table or counter. If you are working with very large tubers, you may need a slightly longer piece.
Step 2: The First Tuber
Place one tuber at the very edge of the plastic wrap. Roll the wrap over the tuber until it is completely encased in one layer of plastic.
Step 3: Adding More Tubers
Place a second tuber of the same variety next to the first one. Continue rolling the plastic wrap. It is essential that the second tuber is separated from the first by a layer of plastic. They should never touch skin-to-skin. This "buffer" is what prevents rot from spreading if one tuber fails.
You can typically fit 3 to 5 tubers in one "log" or bundle. Once you reach the end of the plastic, fold the ends over like a burrito to seal the package. This keeps the moisture levels consistent throughout the winter.
Step 4: Labeling the Bundle
Even though you labeled the plants in the garden, you need to label the bundles now. You can use a permanent marker to write the variety name directly on the outside of the plastic wrap. Alternatively, some gardeners like to write the name on the skin of the tuber with a soft pencil or garden marker before wrapping. At our trial gardens, we find that a piece of masking tape on the outside of the bundle is the easiest way to keep things organized.
Key Takeaway: The secret to this method is ensuring that every tuber is separated from its neighbor by at least one layer of plastic wrap. This creates an individual "mini-environment" for each tuber.
Where to Store Your Wrapped Tubers
Once your tubers are safely bundled, they need a home for the winter. The ideal storage temperature for dahlia tubers is between 40°F and 50°F (4°C to 10°C).
If the temperature is too warm (above 55°F), the tubers may think it’s spring and start to grow inside the wrap. This uses up their stored energy too early. If the temperature is too cold (below 35°F), the tubers can freeze. Freezing turns the cells of the tuber into mush, and they will not survive.
A cool, dark basement, an insulated garage that doesn't freeze, or a crawl space are usually the best spots. Place your plastic-wrapped bundles into a cardboard box or a plastic crate. Do not seal the lid of a plastic tub tightly; it's better to leave it cracked or use a cardboard box to allow for a tiny bit of air exchange.
Maintaining Your Collection
One of the best things about storing dahlia tubers in plastic wrap is that they are "set it and forget it." Unlike tubers stored in peat moss, which may need to be misted with water if they get too dry, wrapped tubers generally hold their moisture all the way until spring.
However, it is still a good idea to check your boxes once a month. Look through the clear plastic. If you see a tuber that has turned dark and mushy, simply unroll the bundle, remove the bad tuber, and re-wrap the healthy ones. Because of the plastic barrier, it’s rare for rot to jump from one wrapped tuber to another.
If you notice a small amount of condensation inside the plastic, don't panic. A little bit of "sweat" is normal as the tubers settle into their dormant state. As long as the tuber remains firm to the touch, it is doing just fine.
Preparing for Spring Planting
When the weather begins to warm and the danger of frost has passed, it’s time to unwrap your dahlias. This is often the most exciting part of the process. When you unroll the plastic, you should find tubers that are almost as firm as the day you put them in.
You might even see "eyes" that have started to sprout into small, pale white or purple nubs. This is a great sign! It means the tuber is healthy and ready to grow. If some tubers still don't show eyes, you can "wake them up" by placing them in a warm, bright spot for a few days before planting. For more help with spring growth habits, see How to Pinch and Stake Dahlias.
At Longfield Gardens, we recommend planting your tubers once the soil has warmed to about 60°F. If you plant them in cold, wet soil too early, they may sit dormant for a long time. Waiting for that spring warmth ensures they hit the ground running and produce those spectacular blooms you've been waiting for all winter.
What to Do in Spring
- Check for firm, plump tubers as you unwrap.
- Look for visible "eyes" or small sprouts.
- Discard any that feel completely hollow or soft.
- Wait for warm soil before placing them in the garden.
Common Myths About Plastic Wrap Storage
As you research how to store dahlia tubers in plastic wrap, you might come across some conflicting advice. Let's clear up a few common misconceptions:
Myth 1: "Tubers will suffocate without air." While plants need oxygen, dormant tubers have a very low metabolic rate. The tiny amount of air trapped inside the plastic wrap, combined with the slight permeability of many plastic films, is usually more than enough for a dormant tuber to survive the winter.
Myth 2: "You must use a fungicide." Some people suggest dipping tubers in a bleach solution or dusting them with sulfur before wrapping. While this can help if you've had major rot issues in the past, it isn't strictly necessary for most home gardeners. As long as your tubers are clean and dry before they go into the wrap, they should stay healthy on their own.
Myth 3: "Plastic wrap causes rot." Plastic wrap doesn't cause rot; moisture and bacteria do. If a tuber rots in plastic wrap, it was likely already infected or was wrapped while it was still too wet. When done correctly, the plastic wrap actually helps prevent the spread of rot.
Conclusion
Storing dahlia tubers in plastic wrap is a simple, effective, and space-saving way to keep your garden favorites safe through the winter. By following the steps of digging, cleaning, drying, and careful wrapping, you can ensure a high success rate and a beautiful display of flowers year after year. This method removes much of the guesswork and bulk associated with traditional storage, making it perfect for gardeners of all experience levels.
Gardening is all about the joy of the process, and there is a special kind of satisfaction in unwrapping a healthy, plump tuber in the spring. It’s a reminder of the beauty to come and a great way to grow your dahlia collections without extra cost.
- Wait for a frost before digging to ensure the tubers are mature.
- Dry the tubers thoroughly for 24–48 hours before wrapping.
- Use a "roll and separate" technique so tubers never touch each other.
- Store in a cool, dark place between 40°F and 50°F.
Protecting your dahlia tubers over the winter is one of the best ways to ensure your garden stays vibrant and full of color. With a little bit of plastic wrap and a cool corner in your basement, you'll be ready for another spectacular growing season.
If you are looking to add new varieties to your collection or need more supplies for the upcoming season, we are here to help. Explore our Pink & Purples selection at Longfield Gardens to find your next favorite dahlia and get ready for a beautiful summer ahead.
FAQ
Can I wrap multiple varieties together in one plastic bundle?
It is best to keep different varieties in separate bundles to avoid confusion in the spring. If you do mix them, make sure each individual tuber is clearly marked with its variety name using a permanent marker on the skin. This prevents the heartbreak of planting what you thought was a tall dinnerplate dahlia in a spot meant for a dwarf border variety.
What should I do if my tubers feel slightly soft when I unwrap them?
A little bit of "give" is normal after several months in storage, but the tuber should not feel like a sponge. If it's only slightly soft, go ahead and plant it; once it hits moist soil, it will often rehydrate and grow perfectly well. However, if the tuber is shriveled and prune-like, it may have lost too much moisture to recover.
Do I need to use a specific brand of plastic wrap?
No, any standard clear plastic wrap from the grocery store will work. The key is the physical barrier it provides and its ability to cling to itself to create a seal. Avoid using "press and seal" types or heavy-duty aluminum foil, as these don't provide the same visibility or moisture-balancing properties as standard clear wrap.
Is it okay to store the wrapped bundles in the refrigerator?
While a refrigerator stays at a good temperature for dahlias, it is often too dry and can pull moisture out of the tubers. Additionally, storing tubers near ripening fruits (like apples) can be harmful because the ethylene gas produced by the fruit can damage the eyes of the dahlia. A cool basement or insulated garage is a much better choice for long-term success.
