How Do I Store Dahlia Bulbs for the Winter?

Table of Contents

1. Introduction
2. Knowing When to Dig Your Dahlias
3. How to Dig Dahlia Tubers Carefully
4. Cleaning and Curing Your Tubers
5. Choosing a Packing Method
6. Finding the Perfect Storage Location
7. To Divide or Not to Divide?
8. Monitoring Your Dahlias Through the Winter
9. Preparing for Spring
10. A Simple Summary for Success
11. FAQ

Introduction

There is nothing quite like the late-summer magic of a dahlia garden in full bloom. From the dinnerplate varieties that command attention to the delicate pompons that brighten every bouquet, these flowers are the crown jewels of the garden. At Longfield Gardens, we believe that the joy of growing dahlias shouldn't end when the first frost arrives. Because these plants are native to the warm climates of Mexico and Central America, they need a little extra help to survive the winter in most parts of the United States.

Storing your dahlia tubers—which many gardeners simply call "bulbs"—is a straightforward and rewarding process. Whether you're saving pompons or dinnerplates, it allows you to save your favorite varieties, watch your collection grow, and enjoy even more blooms next summer. This guide will show you how to identify the right time to harvest, how to pack your tubers safely, and how to keep them healthy until spring. With just a few simple steps, you can ensure your garden returns even more beautiful year after year.

Knowing When to Dig Your Dahlias

The most important factor in successfully storing dahlias is timing. While it might be tempting to pull them up as soon as the weather turns chilly, waiting for the right signals from nature leads to much better results. In most regions, dahlias are treated as annuals unless the tubers are lifted and stored indoors. If you want to expand your display next year, browse our dahlia collections.

In the late fall, you will notice your dahlia plants beginning to slow down. The secret to a healthy, vigorous tuber for next year is allowing the plant to stay in the ground as long as possible. This extra time allows the plant to send all its energy down into the root system, "charging" the tuber for its next growth cycle.

The First Frost Signal

For most gardeners, the "first frost" is the ultimate green light. A light frost will usually cause the dahlia foliage to turn black or dark brown. This is completely normal and is the plant's way of entering dormancy.

Once the foliage has blackened, wait about 10 to 14 days before you start digging. This waiting period is crucial because it triggers the "eyes" on the tubers to become more visible and allows the outer skin of the tuber to toughen up slightly, which helps prevent rot during storage. If you live in a region where a hard freeze (temperatures below 28°F) is expected immediately after the first frost, you may want to move a bit faster, but a week of "curing" in the ground is generally ideal. If you're not sure which climate zone you're in, our hardiness zone map can help.

Identifying Your Garden Layout

Before you start digging, make sure your labels are still in place. It is easy to remember which dahlia is which when they are in bloom, but once the stems are cut back and the tubers are out of the ground, they all look remarkably similar. If your labels have faded or gone missing, tie a fresh tag to the base of the stem before you cut the plant down. For a step-by-step refresher, see How to Lift and Store Dahlia Bulbs.

Key Takeaway: Wait until a light frost turns the dahlia foliage black, then give the tubers about two weeks in the soil to "set" before you begin the digging process.

How to Dig Dahlia Tubers Carefully

Once the waiting period is over, it is time to lift your dahlias. The goal is to remove the entire clump of tubers without nicking, bruising, or breaking them. Since dahlia tubers grow in a cluster around the base of the main stem, they can be wider than you might expect. For a broader overview of dahlia care, see All About Dahlias.

Step 1: Cutting Back the Foliage

Start by cutting the main stalks down to about 4 to 6 inches above the soil line. This provides you with a sturdy "handle" to hold onto while you work, without having to manage several feet of heavy, dying foliage. Use sharp, clean bypass pruners or a garden saw for thicker stems.

Step 2: The Wide Circle Technique

Instead of a pointed shovel, we recommend using a garden fork. A fork is less likely to slice through a tuber than a solid blade.

Insert your garden fork into the soil at least 12 inches away from the main stem. Gently pry upward, then move the fork a few inches and repeat the process in a circle around the plant. This loosens the soil and slowly lifts the entire root ball. By working in a wide circle, you ensure that even the longest tubers remain intact.

Step 3: Lifting the Clump

Once the soil is loose, reach down and grasp the base of the stem. Gently lift the clump out of the ground. Don't worry if there is a lot of soil attached; we will address that in the next step. If you feel resistance, stop and use the fork to loosen the soil a bit more. Forcing the plant up can snap the "neck" of the tuber, which is where the growth buds are located. A tuber with a broken neck will not grow next year.

Cleaning and Curing Your Tubers

With the tubers safely out of the ground, the next step is preparation. Proper cleaning and drying are the best defenses against rot and mold. For more dahlia care basics, see 8 Tips for Growing Better Dahlias.

Rinsing vs. Brushing

There are two schools of thought on cleaning dahlias. Many gardeners prefer to use a garden hose to gently wash away the soil. This makes it much easier to see the tubers and check for any signs of damage or pests. If you choose this method, use a gentle spray rather than a high-pressure blast.

If your soil is very sandy and falls away easily, you can simply brush off the excess dirt with your hands. Regardless of the method you choose, avoid using a scrub brush or anything that could tear the delicate skin of the tuber.

The Drying Phase

This is a vital step known as "curing." Find a cool, dry place that is protected from direct sunlight and frost—a garage, shed, or basement works well. Place the tubers on a layer of newspaper or a mesh screen. Some gardeners prefer to hang the clumps upside down by their stems to allow any moisture trapped in the hollow stalks to drain out.

Let the tubers dry for 24 to 48 hours. The goal isn't to dry them out completely, but rather to ensure the outer surface is no longer damp to the touch. If the tubers are left out for too long, they may begin to shrivel, which we want to avoid.

Final Trimming

Once the tubers are dry, take your pruners and trim the main stem down even further, leaving just an inch or two. You should also trim away any "hair-like" feeder roots and any tubers that feel mushy or appear damaged. If you see a tuber that is hanging by a thread or has a broken neck, go ahead and remove it now.

What to Do Next:

• Cut stems to 4-6 inches before digging.
• Use a garden fork to lift the plant from a 12-inch distance.
• Gently rinse or brush off the soil.
• Air-dry in a cool, dark spot for 1-2 days.

Choosing a Packing Method

Now that your tubers are clean and cured, they need a "home" for the winter. The goal is to provide an environment that is dry enough to prevent rot, but humid enough to prevent the tubers from shriveling into raisins. If you want a ready-made dinnerplate mix, try the Dahlia Dinnerplate High Summer Mix.

The Medium Matters

At Longfield Gardens, we have found that packing tubers in a slightly insulating medium provides the most consistent results. You have several great options:

• Coarse Vermiculite: This is a popular choice because it holds just the right amount of moisture and is very lightweight.
• Peat Moss: A classic gardening staple. Ensure the peat moss is only slightly damp—if you squeeze it, no water should come out.
• Pine Shavings: Often sold as animal bedding, these provide excellent air circulation and are very affordable.
• Sawdust or Shredded Paper: These are good budget-friendly alternatives, though you should check them more frequently to ensure they aren't wicking too much moisture away from the tubers.

Containers for Storage

You can store your packed tubers in cardboard boxes, plastic bins, or even paper bags.

• Cardboard Boxes: These are excellent because they allow for some air exchange.
• Plastic Bins: These hold moisture very well, which is great for dry climates. However, if you use plastic, do not snap the lid on tight. Leave it slightly ajar or drill a few small holes in the sides to prevent condensation from building up.
• Paper Bags: These are ideal for small collections. Place the tubers in the bag and fill the gaps with your chosen medium.

The "Plastic Wrap" Method

Some gardeners have success by wrapping individual, clean, and dry tubers tightly in plastic kitchen wrap. This method takes more time upfront but can prevent rot from spreading from one tuber to another. However, if you are a beginner, the "bulk packing" method in a box with peat moss or vermiculite is usually the easiest way to start.

Finding the Perfect Storage Location

The environment where you keep your boxes will determine if your dahlias stay dormant or start to rot. Dahlias like to stay "cool but not cold."

The Ideal Temperature

The "goldilocks" temperature range for dahlia storage is between 40°F and 50°F. If the temperature stays consistently in this range, the tubers will remain dormant and firm.

• Too Cold: If the temperature drops below 32°F, the tubers will freeze. Once a dahlia tuber freezes, its cells rupture, and it will turn into a mushy mess when it thaws.
• Too Warm: If the temperature stays above 55°F, the tubers may think it is springtime and begin to sprout prematurely, or they may dry out too quickly.

Common Storage Spots

An unheated basement, a crawl space, or an insulated garage are usually the best spots. Avoid placing your storage boxes directly on a concrete floor, as concrete can pull cold or moisture into the box. Instead, place the boxes on a shelf or a wooden pallet. For shipping timing by zone, see our Shipping Information.

Darkness is Key

Keep your tubers in a dark place. Light can encourage the eyes to sprout before you are ready to plant them in the spring.

To Divide or Not to Divide?

One of the most common questions we receive is whether you should divide your dahlia clumps in the fall or wait until spring. Both methods work, but there are advantages to each.

Dividing in the Fall

Some gardeners like to divide their tubers right after digging. The tubers are softer and easier to cut at this time. It also saves storage space, as you aren't storing the "mother tuber" or any pieces that aren't viable. The challenge is that the "eyes" (the small bumps where next year's stems grow) can be very hard to see in the fall.

Dividing in the Spring

We often recommend that beginners wait until spring to divide their clumps. By March or April, the eyes will begin to swell and may even turn slightly pink or green. This makes it incredibly easy to see exactly where to cut so that every piece you plant is guaranteed to have a growth bud. For planting and support tips, see How to Pinch and Stake Dahlias.

If you choose to store the whole clump, simply pack the entire root mass into your box and cover it with your storage medium.

Monitoring Your Dahlias Through the Winter

Storing dahlias isn't a "set it and forget it" task. To ensure the best success rate, you should check on your tubers about once a month. This small effort can save your entire collection if conditions change.

What to Look For

When you open your storage boxes, look for two main things: rot and shriveling.

1. If you see rot: If a tuber feels soft, mushy, or has visible mold, remove it immediately. Use a clean knife to cut away any affected areas or simply discard the individual tuber. This prevents the rot from spreading to the rest of the healthy clump.
2. If you see shriveling: If the tubers are starting to look like wrinkled prunes, they are losing too much moisture. Use a spray bottle to lightly mist the storage medium (not the tubers directly) with a little water. This will raise the humidity inside the box.

Maintaining Air Quality

If you notice a "musty" smell when you open your storage area, it is a sign that there isn't enough air circulation. You might want to crack a window for a few minutes on a mild day or move the boxes to a slightly more ventilated area. If you run into an order issue, our 100% guarantee page explains how we help.

Key Takeaway: A quick monthly check allows you to adjust moisture levels and remove any "bad apples" before they affect your healthy tubers.

Preparing for Spring

As the days get longer and the ground begins to thaw, your dahlias will start to wake up. This is a very exciting time for any gardener.

Waking Up the Tubers

In late March or early April, you can bring your boxes into a slightly warmer area (around 60°F). This gentle warmth encourages the eyes to start "pipping." If you haven't divided your tubers yet, this is the perfect time to do it. For spring planting and support tips, see How to Pinch and Stake Dahlias.

When to Plant

Wait until all danger of frost has passed and the soil has warmed to at least 60°F before planting your dahlias back in the garden.

Dahlias are fast growers, so even if you wait until late May or early June to plant, you will still have a magnificent display of flowers by mid-summer.

A Simple Summary for Success

Storing dahlias doesn't have to be complicated. By following the rhythms of the seasons and keeping a close eye on your tubers, you can enjoy these spectacular flowers year after year. Remember that gardening is a learning experience, and each year you will get better at identifying the perfect moisture balance for your specific storage spot.

• Timing: Dig about two weeks after the first frost.
• Care: Use a garden fork and lift a wide area to keep tubers intact.
• Curing: Dry for 24-48 hours in a cool, dark place.
• Packing: Use a medium like peat moss or pine shavings in a ventilated box.
• Environment: Store between 40°F and 50°F.
• Monitoring: Check monthly for rot or shriveling.

"The effort spent tucked away in the fall pays off in a garden full of color and joy the following summer. Saving your own tubers is one of the most rewarding parts of being a dahlia lover."

At Longfield Gardens, we are here to support your gardening journey every step of the way. If you are looking to expand your collection, browse our dahlia collections. Happy gardening!

FAQ

Can I leave my dahlia tubers in the ground if I live in a warm climate?

If you live in USDA hardiness zones 8 through 11, you can often leave dinnerplate dahlias in the ground over the winter. However, it is a good idea to cover them with a thick layer of mulch to protect them from excessive winter rain, which can cause rot. In zone 7, leaving them in the ground is a gamble that depends on how much drainage your soil has and how severe the winter is.

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

If you find a small amount of surface mold, wipe it off with a cloth dipped in a very weak solution of water and white vinegar. Check the storage medium; if it feels damp, replace it with fresh, dry material. If the tuber itself feels soft or mushy, it is best to cut that portion away or discard the tuber to prevent the mold from spreading.

How do I tell the difference between a dahlia "eye" and a regular bump?

Dahlia eyes are usually located on the "crown" of the tuber, right where the tuber attaches to the main stem. They look like small, raised pimples or tiny dormant buds. If you can't see them in the fall, don't worry—they become much more prominent in the spring when they turn slightly pink or white and begin to swell.

Can I store dahlias in a refrigerator?

While a refrigerator stays in the correct temperature range, it is usually not a good idea for dahlia storage. Most refrigerators are designed to remove humidity, which will cause your tubers to shrivel very quickly. Additionally, ripening fruits and vegetables in a fridge release ethylene gas, which can damage the dormant buds on the tubers and prevent them from growing.