How to Lift and Store Dahlia Tubers for Winter

Table of Contents

1. Introduction
2. Why Lifting Dahlias Is a Rewarding Step
3. Understanding Timing and Your Local Climate
4. Essential Tools for Lifting and Storage
5. Step 1: Preparing and Cutting Back
6. Step 2: Lifting the Tubers Safely
7. Step 3: Cleaning and Rinsing
8. Step 4: Drying and Curing
9. Step 5: Identifying the Anatomy of a Tuber
10. Step 6: To Divide or Not to Divide?
11. Step 7: Choosing the Right Storage Medium
12. Step 8: Packing Your Tubers for Winter
13. Step 9: Finding the Ideal Storage Location
14. Step 10: The Winter Check-In
15. Replanting Your Dahlias in the Spring
16. Conclusion
17. FAQ

Introduction

There is a unique kind of magic in a late-summer dahlia garden. From the dinnerplate-sized blooms of Cafe au Lait to the perfectly geometric petals of pompon varieties, these flowers offer a spectacular finale to the growing season.

We believe that every gardener can successfully keep their favorite varieties thriving season after season. At Longfield Gardens, we want to help you preserve that floral investment so you can enjoy an even bigger display of dinnerplate dahlias next summer.

This guide will walk you through the simple, practical steps for protecting your dahlias during the winter months and the exciting possibilities of new dahlias next spring. With a few basic tools and a bit of patience, you can ensure your dahlias return with more vigor and more blooms every year.

Why Lifting Dahlias Is a Rewarding Step

Dahlias are native to the warm mountain regions of Mexico and Central America. Because they evolved in a frost-free climate, their tubers are full of water and sensitive to freezing temperatures. In most parts of the United States, particularly in USDA hardiness zones 3 through 7, the ground freezes deep enough to damage these tubers if they are left outdoors.

Lifting your tubers is about more than just survival; it is about abundance. A single dahlia tuber planted in the spring will often grow into a large clump of five to twenty new tubers by autumn. When you lift and store these clumps, you have the opportunity to divide them. This means you can turn one plant into five or ten plants for the following year.

Storing your own tubers also allows you to keep rare or favorite dahlia varieties that might be hard to find again. It is a cost-effective and satisfying way to expand your garden. By taking the time to store them correctly, you are participating in a timeless gardening tradition that turns a single season of color into a lifetime of flowers.

Understanding Timing and Your Local Climate

The key to successful storage begins with the right timing. You want the tubers to stay in the ground as long as possible so they can fully mature and store up the energy needed for next year’s growth. However, you must get them out before the ground freezes solid.

For most gardeners, the signal to start is the first killing frost. This is the frost that turns the lush green dahlia foliage into a dark brown or black color. While the top of the plant looks finished, the tubers underground are perfectly safe. In fact, many gardeners like to wait about a week or two after this first frost before digging. This short waiting period encourages the tubers to develop "eyes"—the small bumps that will become next year's stems—making them much easier to see when it comes time to divide.

Regional Timing Guidelines

• Zones 3–5: Expect to lift your tubers in late September or October.
• Zones 6–7: This usually happens in late October or November.
• Zones 8–10: In these warmer regions, dahlias can often stay in the ground year-round. If your soil stays relatively dry and doesn't freeze, you can simply cut the stems back and apply a thick layer of mulch. However, many gardeners in these zones still lift their dahlias every few years to divide the clumps and prevent overcrowding.

Key Takeaway: Wait for the first frost to blacken the foliage before you begin the lifting process. This ensures the tubers are mature and dormant.

Essential Tools for Lifting and Storage

You do not need specialized machinery to save your dahlias. A few common garden tools will make the job easy and efficient.

• Pruning shears or loppers: Used to cut through the thick, hollow stems.
• Pitchfork or garden fork: This is the best tool for lifting. Unlike a flat shovel, a fork is less likely to slice through the tubers hidden underground.
• Garden hose with a spray nozzle: To gently wash away soil.
• Labeling materials: Waterproof markers and tags are essential so you don't lose track of which variety is which.
• Storage containers: Cardboard boxes, plastic bins (with holes for ventilation), or paper bags.
• Storage medium: Dry peat moss, vermiculite, or wood shavings.

Step 1: Preparing and Cutting Back

Once the frost has arrived and you are ready to dig, the first step is to clear the foliage. Using your shears or loppers, cut the main stems down so only about 4 to 6 inches of the stalk remains above the soil. This remaining stem serves as a helpful "handle" when you are lifting the clump.

Dahlia stems are hollow, much like a straw. Because of this, they can sometimes collect water. If you have the time, you can leave the cut stalks in the ground for a few days to "cure." This helps the skin of the tubers toughen up slightly for storage. If rain is in the forecast, you can cover the open hollow stems with a little piece of aluminum foil to keep water from sitting inside the crown, which can cause rot.

Step 2: Lifting the Tubers Safely

Lifting a dahlia clump is a bit like an archaeological dig. The tubers grow outward from the center, often spreading further than you might expect. To keep the tubers intact, you need to give them plenty of space.

Start by placing your garden fork in the soil about 12 inches away from the center of the stalk. Gently push the fork down and lean back to loosen the soil. Work your way in a circle all the way around the plant. Once the soil is loose on all sides, gently pry the entire clump upward.

Avoid the temptation to grab the stem and pull hard. The "neck" of a dahlia tuber—the narrow part where it connects to the main stalk—is very fragile. If the neck snaps, that tuber will likely not grow next year. Instead, use your fork to lift from underneath while supporting the clump with your hand.

What to do next:

• Clear a space on a lawn or driveway where you can work.
• Slowly lift each clump, keeping as much soil attached as possible to cushion the tubers.
• Move the clumps to your cleaning station immediately to prevent them from drying out too fast in the sun.

Step 3: Cleaning and Rinsing

Once the tubers are out of the ground, you will want to remove the excess soil. Cleaning the tubers makes it easier to see the "eyes" and helps prevent soil-borne diseases from following the plants into storage.

Use a garden hose with a gentle spray to wash away the dirt. You don't need to scrub them; just let the water do the work. While you are cleaning, keep an eye out for any tubers that look damaged, soft, or "mushy." It is best to remove any rotten pieces now so they don't affect the healthy parts of the clump during the winter.

Step 4: Drying and Curing

After washing, the tubers will be wet. Storing wet tubers is the most common cause of rot, so drying is a critical step.

Place your cleaned clumps in a cool, shaded area with good air circulation. A garage, a covered porch, or a shed works well. Avoid placing them in direct sunlight, as this can cause the tubers to shrivel. Turn the clumps upside down so any water trapped in the hollow stems can drain out.

Let them dry for 24 to 48 hours. The goal is for the skin of the tuber to feel dry to the touch, like a potato. You are not trying to dry them out completely—just remove the surface moisture.

Step 5: Identifying the Anatomy of a Tuber

Before you decide whether to divide your dahlias, it helps to understand what makes a dahlia tuber viable. A dahlia tuber is not like a potato; it cannot grow a new plant from any piece of the skin. To grow next year, a tuber must have three specific parts:

1. The Body: This is the fat, carrot-like part that stores energy and water.
2. The Neck: The narrow connection point between the body and the crown.
3. The Eye: This is the most important part. The eyes are located on the "crown" (the area of the main stalk where the tubers attach).

The eye looks like a tiny, raised bump, similar to the eye on a potato. If a tuber breaks off and does not have a piece of the crown with an eye attached, it will grow roots but will never produce a sprout or flowers.

Step 6: To Divide or Not to Divide?

One of the most common questions we hear at Longfield Gardens is whether you should divide the clumps in the fall or wait until spring. Both methods work well, and the choice depends on your preference.

Dividing in the Fall

Many gardeners prefer to divide in the autumn because the tubers are soft and easy to cut.

• Pros: It takes up much less storage space. You can easily spot any rot and remove it immediately.
• Cons: The eyes can be very small and difficult to see right after digging.

Storing the Whole Clump

If you are busy or new to dahlias, storing the entire clump is a great "easy win."

• Pros: It is faster and provides a protective "buffer" for the tubers. The eyes will be much more prominent and easier to see in the spring.
• Cons: Clumps are bulky and require larger storage containers.

If you choose to divide, use a sharp, clean knife. Sterilize the blade with a quick wipe of rubbing alcohol between different varieties to prevent the spread of any potential viruses. Ensure each division has at least one healthy tuber and a piece of the crown with a visible eye.

Key Takeaway: A dahlia tuber must have a piece of the "crown" and a visible "eye" to grow into a plant next season.

Step 7: Choosing the Right Storage Medium

The goal of storage is to keep the tubers dormant, cool, and just slightly moist so they don't shrivel, but not so wet that they rot. This is a delicate balance, and the "medium" you pack them in helps regulate this moisture.

• Peat Moss: This is the most popular choice. It is lightweight and excellent at absorbing excess moisture while keeping the environment around the tuber stable.
• Vermiculite: A mineral that provides great insulation and moisture control. It is very clean and easy to work with.
• Wood Shavings: Often sold as pet bedding, these provide good airflow. Make sure they are relatively dry before use.
• Newspaper: If you are storing individual tubers, you can wrap each one in a few layers of dry newspaper before placing them in a box.

Step 8: Packing Your Tubers for Winter

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

1. Prepare the container: Start with a cardboard box or a plastic bin. If using plastic, make sure there are several holes for ventilation.
2. Add a base layer: Put about two inches of your chosen storage medium at the bottom.
3. Arrange the tubers: Place your tubers or clumps on top of the medium. Try to keep them from touching each other. If one tuber happens to rot, the space between them prevents the rot from spreading to the others.
4. Cover them up: Add more medium until the tubers are completely covered. You can stack multiple layers in a deep box, as long as there is medium between each layer.
5. Label everything: This is the step people often regret skipping! Use a waterproof pen to write the variety name on a tag or even directly on the skin of a large tuber.

Step 9: Finding the Ideal Storage Location

The perfect storage spot is cool, dark, and frost-free. The temperature should ideally stay between 40°F and 50°F.

• Unheated Basements: Often provide the most consistent temperatures and humidity.
• Attached Garages: Can work well, but you must ensure the temperature doesn't drop below freezing during a cold snap.
• Root Cellars: The traditional choice for storing tubers and root vegetables.

Avoid areas near a furnace or water heater, as these spots are too warm and dry, which will cause the tubers to shrivel and die.

Step 10: The Winter Check-In

Gardening in the winter is mostly about observation. We recommend checking on your stored tubers once a month. This small effort can save your entire collection.

Open your boxes and feel a few tubers.

• If they feel mushy or smell bad: This is rot. Remove the affected tubers immediately and discard them. If the storage medium feels damp, replace it with fresh, dry material.
• If they feel light and look shriveled: They are getting too dry. You can lightly mist the storage medium with a spray bottle of water. You don't want it wet, just "barely damp" to the touch.

Most tubers will come through the winter looking slightly wrinkled, which is perfectly normal. As long as they remain firm, they are healthy and ready for spring.

Replanting Your Dahlias in the Spring

The excitement begins again when the days grow longer. In the spring, you can take your tubers out of storage about 4 to 6 weeks before the last frost date. This is a great time to finish any dividing you didn't do in the fall, as the eyes will now be very easy to see.

Wait until the soil has warmed to about 60°F before planting them directly in the garden. For a refresher, see How to Plant Dahlias. For most of the US, this is the same time you would plant tomatoes or peppers. If you want a head start, you can "pot up" your tubers indoors in April to give them a few weeks of growth before they head outside.

When you see those first green shoots poking through the soil, you will know that your autumn efforts were a success. The cycle of beauty begins again, often with even more flowers than the year before.

Conclusion

Lifting and storing dahlia tubers is one of the most satisfying tasks in the gardening calendar. It allows you to protect the plants you love and participate in the natural cycle of growth and dormancy. While it may seem like a lot of steps at first, remember that dahlias are resilient plants that want to grow.

By following the simple rules of timing, careful lifting, and cool storage, you can build a massive dahlia collection over time. We enjoy seeing our customers' gardens grow more vibrant each year as they master these simple techniques. At Longfield Gardens, our goal is to make dahlias accessible to everyone, ensuring your yard remains a place of joy and color.

Final Tips for Success:

• Label every variety as soon as you dig it up.
• Store tubers in a cool, dark place (40-50°F).
• Check for rot or shriveling once a month during winter.
• Enjoy the abundance of free plants you've created for next season!

Take that first step this autumn and lift your tubers. You will be so glad you did when the first blooms of next summer arrive in your garden.

FAQ

When is the best time to lift my dahlia tubers?

The ideal time is shortly after the first killing frost has turned the foliage brown or black. This frost signals the plant to go dormant and allows the tubers to finish maturing. If you live in an area that does not get frost, aim to lift them in late November when the plant naturally begins to slow down.

Can I store dahlia tubers in plastic bags?

You can use plastic bags, but you must be very careful. Plastic traps moisture, which can quickly lead to rot. If you choose this method, leave the bag partially open for ventilation or use a "breathable" medium like peat moss inside the bag to help regulate humidity. Most gardeners find that cardboard boxes or ventilated bins are safer options.

What should I do if my tubers look shriveled in mid-winter?

If your tubers are starting to look like dried prunes, they are losing too much moisture. Use a spray bottle to lightly mist the storage medium (the peat moss or shavings) with water. This increases the local humidity without making the tubers wet. Check them again in a week to see if they have firmed up.

Do I have to wash the soil off the tubers before storing?

While you don't strictly have to wash them, it is highly recommended. Soil can harbor fungi and bacteria that may cause rot during the winter. Cleaning the tubers also makes it much easier to inspect them for damage and to find the eyes when you are ready to divide or replant them in the spring.