How to Store Dahlia Bulbs for a Beautiful Spring

Table of Contents

1. Introduction
2. Knowing When to Begin the Harvest
3. Preparing the Plants for Digging
4. The Proper Way to Dig Dahlia Tubers
5. Cleaning and Inspecting the Tubers
6. To Divide or Not to Divide?
7. Creating the Perfect Storage Environment
8. Packing Your Tubers for Winter
9. Monitoring During the Winter
10. Planning for Spring
11. Summary of Best Practices
12. FAQ

Introduction

There is nothing quite like the late-summer magic of a garden filled with dahlias. These vibrant, dinnerplate-sized blooms are often the pride of the backyard, offering a color palette that stretches from soft pastels to deep, velvety purples. As the season winds down, the focus shifts from enjoying those stunning flowers to preserving the tubers for next year. Saving your tubers is one of the most rewarding parts of the gardening cycle. It allows you to grow your collection and enjoy your favorite varieties year after year. If you’re planning next season’s display, explore the Dahlia Dinnerplate Cloud Nine Collection.

At Longfield Gardens, we want to help you make this process as simple and successful as possible. Storing dahlia tubers—often called bulbs by many gardeners—might seem technical at first, but it is a straightforward task that anyone can master. For a broader overview, see All About Dahlias. This guide covers everything from the first frost to the final storage bin. We will walk you through digging, cleaning, and creating the perfect winter environment for your plants.

With a little bit of preparation and the right storage conditions, you can ensure your dahlias return even stronger next season. Success comes down to understanding what the tuber needs during its winter nap.

Knowing When to Begin the Harvest

The timing of your dahlia harvest is the first step toward storage success. In most parts of the United States, dahlias are treated as tender perennials. This means they cannot survive a freezing winter in the ground. You need to wait for the right environmental cues before you start digging. If you want to check your climate window, use the Hardiness Zone Map.

The Signal of the First Frost

For most gardeners, the "killing frost" is the ultimate signal. This is the frost that turns the lush green foliage of your dahlias into a dark, wilted brown or black. While it might look a bit sad, this is actually a helpful part of the process. The frost tells the plant that the growing season is over and it is time to move its energy down into the tubers.

If you live in a region where frost comes very late, look at the calendar instead. Most tubers are ready for harvest about 120 to 135 days after planting. If you reach mid-November and haven't had a frost, you can proceed with the harvest regardless.

The Curing Period

After the frost hits, many experienced gardeners choose to wait a few days before digging. Leaving the tubers in the ground for 3 to 7 days after the foliage dies back helps the "eyes" (the small growth buds) become more visible. It also allows the skins of the tubers to toughen up slightly, which makes them more resistant to damage during the digging and storage process.

If a hard freeze is predicted that might penetrate the soil, do not wait. It is better to dig them a little early than to let the tubers themselves freeze. A frozen tuber will turn to mush and cannot be saved. For a spring refresher, see How to Plant and Grow Dahlia Tubers.

Key Takeaway: Wait for the first frost to turn the foliage brown before you begin. This natural signal ensures the plant has finished its growth cycle for the year.

Preparing the Plants for Digging

Before you bring out the garden fork, you need to clear away the top growth. This makes the workspace cleaner and helps you see exactly where the base of the plant is.

Cutting Back the Stems

Use a clean pair of bypass pruners or loppers to cut the dahlia stems. Aim for about 4 to 6 inches above the soil line. Leaving this "handle" serves two purposes:

1. It gives you a clear marker of where the tuber clump is located.
2. It provides a convenient grip when you are gently lifting the clump out of the loosened soil.

Avoid cutting the stems all the way to the ground level. Having that extra bit of stem helps prevent water from pooling directly in the crown of the tuber clump, which can lead to rot before you even get them out of the garden.

Labeling Your Varieties

If you grow more than one type of dahlia, labeling is the most important part of this step. Once the tubers are out of the ground, they all look very similar. You can write the variety name directly on the stem with a waterproof marker, or use a garden tag tied securely to the stem handle. We recommend doing this before you dig to avoid any mix-ups. If you’re planning to order more plants, browse our Dahlia Collections.

The Proper Way to Dig Dahlia Tubers

Dahlia tubers are surprisingly fragile. They are often compared to potatoes, but their "necks"—the thin part where the tuber connects to the main stem—can snap easily. If the neck breaks, the tuber usually won't grow because it loses its connection to the growth buds.

Choose the Right Tools

A sturdy garden fork or pitchfork is much better for this job than a shovel. A shovel can easily slice through tubers hidden underground. A fork allows you to loosen the soil and lift the clump with less risk of mechanical damage.

Loosen the Soil

Start by inserting your fork into the soil about 12 inches away from the main stem. You want to give the tuber clump plenty of "buffer" room. Push the fork down deep and gently pry upward to loosen the earth. Move around the plant in a circle, loosening the soil from all sides.

Lifting the Clump

Once the soil is loose, gently lift the clump from underneath. Use your hand on the "stem handle" only as a guide, not to pull the plant out with force. If you feel resistance, stop and loosen the soil a bit more. Most dahlia clumps will be quite large by the end of the season, so take your time to lift the entire mass.

What to do next:

• Cut stems to 4-6 inches.
• Label each plant clearly.
• Use a garden fork to loosen soil 12 inches away from the stem.
• Lift gently from underneath the clump.

Cleaning and Inspecting the Tubers

Once the tubers are out of the ground, they need a bit of grooming before they head into storage.

Removing Excess Soil

If your soil is sandy and dry, you may be able to simply shake the clump or use a soft brush to remove most of the dirt. If you have heavy clay soil, the dirt may stick in the crevices of the clump. In this case, you can use a garden hose with a gentle spray to wash the tubers clean.

Washing tubers makes it much easier to see the "eyes" and check for any signs of damage or disease. However, if you wash them, you must be absolutely certain they dry completely before they go into a storage box.

The Inspection Process

Check each clump for two things: rot and damage.

• Rot: Look for soft, mushy spots or an unpleasant odor. If a single tuber in a clump is rotten, cut it away with a clean, sharp knife to prevent the rot from spreading to the healthy parts.
• Damage: If a tuber was sliced by the fork during digging, it’s usually best to remove it. Open wounds are entry points for fungus during the winter.

Air Drying (Curing)

Regardless of whether you washed your tubers, they need a short drying period. Place them in a cool, dry area that is protected from direct sunlight and frost. A garage or a covered porch works well. Turn them upside down so that any moisture trapped in the hollow stems can drain out.

Let them dry for 1 to 3 days. The goal is for the outer skin to feel dry and slightly "corked" or tough, but you do not want the tubers to start shriveling.

To Divide or Not to Divide?

One of the most common questions we hear is whether you should divide the tubers in the fall or wait until the spring. Both methods work, and the choice often depends on your available space and how much time you have.

Dividing in the Fall

Many gardeners prefer to divide their dahlia clumps right after harvest. The tubers are softer and easier to cut at this time. Dividing in the fall also saves a significant amount of storage space, as you are storing individual tubers rather than bulky clumps.

To divide, you must ensure each piece has three things:

1. The Body: The fat, starch-filled part of the tuber.
2. The Neck: The thin connection between the body and the crown.
3. The Eye: The growth bud located on the crown (the area where the tuber meets the stem).

If a tuber does not have an eye, it will never sprout. In the fall, eyes can be very small—they look like tiny bumps or "pimples."

Storing Whole Clumps

If you are short on time, storing the entire clump is a perfectly valid option. Clumps tend to be more resilient to drying out over the winter because they have more mass. You can simply tuck the whole clump into a box and wait until spring to divide it. In the spring, the eyes will be much more prominent and easier to identify. If you want a ready-made mix for next season, see the Dahlia Assorted Harvest Collection.

Creating the Perfect Storage Environment

Dahlia tubers are living things in a state of dormancy. To keep them healthy, you need to mimic a cool, dark underground environment. The "Goldilocks" zone for dahlia storage is a place that is cool but not freezing, and humid but not wet.

Temperature Requirements

The ideal temperature for storing dahlia tubers is between 40°F and 45°F (4°C to 7°C).

• If it gets colder than 35°F, you risk the tubers freezing, which is fatal.
• If it gets warmer than 50°F, the tubers may "wake up" too early and start to sprout, or they may rot more quickly.

Unheated basements, crawl spaces, or insulated garages are usually the best spots in a typical home.

Humidity and Moisture Control

Dahlias need about 80% to 90% humidity to stay plump. If the air is too dry, the tubers will shrivel up like raisins. If the air is too stagnant and damp, they will grow mold and rot. Finding the balance is the key to success. For more growing advice, read 8 Tips for Growing Better Dahlias.

Choosing a Storage Medium

You should never store dahlia tubers completely "naked" in a box. They need a packing material to help regulate moisture. Popular choices include:

• Peat Moss: Excellent at holding just enough moisture without being wet.
• Vermiculite: A mineral that provides great insulation and moisture control.
• Wood Shavings: Often sold as pet bedding, these provide good airflow.
• Pine Bark: Another natural option that helps prevent the tubers from touching each other.

Key Takeaway: Pack your tubers in a medium like peat moss or vermiculite to prevent them from drying out or touching one another.

Packing Your Tubers for Winter

Once your tubers are dry and you have your storage medium ready, it is time to pack them away.

1. Select a Container: Cardboard boxes, plastic bins with ventilation holes, or wooden crates all work well. If you use a plastic bin, make sure it is not airtight. You need some gas exchange to prevent rot.
2. Layer the Medium: Place a 2-inch layer of your chosen storage medium at the bottom of the container.
3. Place the Tubers: Arrange the tubers or clumps so they are not touching each other. This prevents a single spot of rot from spreading to the entire batch.
4. Cover and Repeat: Cover the tubers with more medium until they are fully submerged. You can add multiple layers of tubers in a deep box, as long as there is packing material between them.
5. Final Labeling: Even if the tubers are labeled individually, it is helpful to label the outside of the box with the variety name and the date you packed them. If you’re picturing next year’s display already, the Dahlia Dinnerplate Lavender Perfection is a classic choice.

Monitoring During the Winter

Storing dahlias is not a "set it and forget it" task. We recommend checking on your tubers about once a month throughout the winter. This allows you to catch small issues before they become big problems.

What to Look For

When you open your storage boxes, look for these two common issues:

• Shriveling: If the tubers look wrinkled or feel light and hollow, they are too dry. Mist the storage medium lightly with a spray bottle of water. Do not soak them; you just want to increase the ambient humidity in the box.
• Rot or Mold: If you see white fuzzy mold or soft black spots, remove the affected tuber immediately. If the medium feels soggy, leave the lid off the box for a day or two to let some moisture escape.

Adjusting Your Setup

If you find that your tubers are consistently too dry or too wet, you may need to move them to a different part of the house. For example, if a garage is too cold, move the box further away from the exterior door. If a basement is too dry because of the furnace, consider placing the storage box inside a loosely closed plastic bag to trap more humidity.

Planning for Spring

As the days begin to lengthen in late winter, you might notice the eyes on your tubers starting to swell. This is an exciting sign that spring is on the way!

When the danger of frost has passed and the soil has warmed to at least 60°F, you can bring your tubers out of storage. Many gardeners like to "wake them up" a few weeks early by placing them in a warm, bright spot indoors. This gives them a head start on the growing season. If you’re ordering new tubers for next spring, review our Shipping Information.

If you stored your dahlias as whole clumps, this is the time to divide them. The eyes will be very easy to see now, often appearing as little green or pink shoots.

At Longfield Gardens, we have found that a little bit of winter care goes a long way. The same tubers you enjoyed this year can provide an even more spectacular show next summer, and often, you will have enough divisions to share with friends and neighbors. If you want a softer palette next season, Dahlia Decorative Sweet Surprise is another beautiful choice.

Summary of Best Practices

Successfully storing dahlia tubers is a cycle of careful timing and attentive monitoring. By following these steps, you can keep your garden favorites healthy until the next planting season.

• Timing: Wait for the first frost to signal dormancy.
• Careful Digging: Use a fork to lift the clumps without snapping the necks.
• Cleaning: Remove soil and dry the tubers for 1-3 days before packing.
• Environment: Store at 40-45°F in a medium like peat moss or vermiculite.
• Check-ins: Inspect your tubers monthly for rot or shriveling.

"Gardening is a continuous journey. Saving your own dahlia tubers is one of the best ways to connect the beauty of the past season with the promise of the next."

FAQ

Can I store dahlia tubers in the refrigerator?

While a refrigerator stays within the correct temperature range, it is usually not the best place for dahlia tubers. Refrigerators have very low humidity and are designed to remove moisture from the air, which can cause tubers to shrivel quickly. Additionally, some fruits release ethylene gas which can damage the dormant tubers. A cool basement or garage is a much safer option.

What should I do if my dahlia tubers have mold on them?

If you notice a small amount of surface mold, wipe it off with a dry cloth and leave the storage box open for a day to improve airflow. If the mold is accompanied by soft or mushy tissue, that tuber is rotting. You should remove and discard any rotting tubers immediately so the infection does not spread to the rest of your collection. If you’re ever concerned about a product issue, review our About Us and Our Guarantee.

Do I need to wash the dirt off before storing them?

Washing is not strictly necessary, but it can be helpful. Removing the dirt makes it easier to spot "eyes" and check for damage or rot. If you have sandy soil, a simple brushing is often enough. If you do choose to wash your tubers, ensure they are completely dry to the touch before you pack them in their storage medium.

Is it okay if the tubers look a little wrinkled?

A small amount of wrinkling is normal as the tubers lose a tiny bit of moisture during dormancy. However, if they feel very soft or look like a prune, they are too dry. You can mist the packing material (like peat moss or wood shavings) with a little water to help rehydrate the environment, but avoid getting the tubers themselves soaking wet.