Table of Contents
- Introduction
- Understanding Why We Dig Dahlias
- Timing: When to Dig Your Dahlias
- Step 1: Preparing the Plants
- Step 2: Digging the Tubers Correctly
- Step 3: Cleaning and Curing
- Step 4: To Divide Now or Wait Until Spring?
- Step 5: Choosing Your Storage Method
- Step 6: Winter Maintenance
- Common Myths and Internet Hacks
- Preparing for Spring
- Summary of the Process
- FAQ
Introduction
There is nothing quite like the peak of dahlia season. From the massive, velvet petals of dinnerplate varieties to the intricate, honeycomb patterns of pompons, these flowers are the crown jewels of the late-summer garden. When autumn arrives and the first frost settles on the landscape, you don’t have to say a permanent goodbye to your favorite varieties. Because dahlias grow from underground tubers, you can save them and plant them again next year, often with even more tubers than you started with.
At Longfield Gardens, we want to make sure your gardening experience is as rewarding as possible. Digging and storing tubers might seem like a complex task, but it is actually a straightforward process that any home gardener can master. It just requires a bit of timing and the right storage conditions to keep your plants healthy through the winter. If you want a bold, ready-made option, browse the Dahlia Dinnerplate High Summer Mix. This guide will walk you through every step, from the first frost to the spring wake-up call. By following these simple steps, you can protect your investment and enjoy an even more spectacular dahlia display next season.
Understanding Why We Dig Dahlias
Dahlias are tender perennials. See our full dahlia collection if you’re planning your next planting. In their native climates of Mexico and Central America, they stay in the ground year-round. However, in most parts of the United States, the frozen winter soil is too cold for them to survive. If the tubers freeze, the water inside their cells expands and turns the tuber into mush.
In USDA hardiness zones 8 and warmer, some gardeners find success leaving their dahlias in the ground with a thick layer of mulch for protection. If you’re unsure of your zone, our Hardiness Zone Map can help. But for those of us in zones 7 and colder, digging the tubers is the best way to ensure they return. Even in warmer zones, many people choose to dig their tubers every couple of years to divide the clumps and keep the plants from becoming overcrowded.
A single dahlia tuber planted in the spring will grow into a large clump of tubers by autumn. This means that by saving your tubers, you aren't just preserving one plant; you are often tripling or quadrupling your stock for free. It’s one of the most exciting "bonuses" of growing these beautiful flowers. If you like mixing forms and colors, our Dahlia Collections are a fun way to plan ahead.
Timing: When to Dig Your Dahlias
Timing is perhaps the most important factor in successful dahlia storage. If you dig too early, the tubers may not be fully mature and might shrivel during the winter. If you wait too long and the ground freezes solid, the tubers will be ruined.
The First Frost Signal
For most gardeners, the "killing frost" is the best indicator that it’s time to get to work. A light frost might nip the top leaves, but a killing frost will turn the entire plant black or dark brown almost overnight. While it looks a bit sad, this is actually a helpful signal. The plant has stopped sending energy to the blooms and is now focusing all its resources on the tubers below.
The Two-Week Rule
After the frost kills the foliage, many experienced growers recommend waiting about 10 to 14 days before digging. This short "rest" period in the ground allows the tubers to go into dormancy and toughens their skin, which helps them survive storage. It also encourages the "eyes" (the small bumps where next year’s growth will emerge) to become more visible.
If you live in a region where a killing frost doesn't arrive until very late, or if your soil is becoming dangerously wet and cold, you don't have to wait for the frost. You can cut the plants back manually in mid-to-late October and proceed with the digging process about two weeks later.
Key Takeaway: Wait for a killing frost to turn the foliage black, then wait 10–14 days for the tubers to toughen up before you start digging.
Step 1: Preparing the Plants
Before you pick up a shovel, you need to clear the way. Start by cutting the dahlia stalks down to about 4 to 6 inches above the soil line. You can use sharp garden loppers or a hand saw for thick, woody stems.
Why Leave a "Handle"?
Leaving a few inches of stem serves two purposes. First, it gives you a "handle" to hold onto while you're lifting the heavy clump (though you should never pull on it too hard!). Second, it helps you keep track of where the center of the plant is so you don't accidentally slice through the tubers with your tools.
The Importance of Labeling
This is the moment where most mistakes happen. Once the flowers are gone and the stalks are cut, every dahlia clump looks exactly the same. We recommend labeling each plant before or immediately after cutting the stems. You can use weather-resistant garden markers, or simply tie a plastic tag around the remaining stem handle. Write the variety name clearly. If you have lost the name, you can label it by color and height (e.g., "Tall Pink Dinnerplate").
Step 2: Digging the Tubers Correctly
Dahlia tubers are surprisingly fragile. The "neck"—the narrow part where the tuber connects to the main stem—is particularly prone to snapping. If the neck breaks, the tuber usually won't grow, even if the rest of it looks healthy.
Choosing the Right Tools
A garden fork (sometimes called a pitchfork) is generally better than a shovel. The tines of a fork can slide into the soil and lift the clump without creating as much suction or resistance as a flat shovel blade.
The Digging Radius
Start by standing about 12 inches away from the main stem. Push your fork deep into the soil and gently pry upward. Work your way in a circle all the way around the plant. This loosens the "feeder roots" and ensures you aren't cutting off the ends of the long tubers.
Once you have loosened the soil in a full circle, gently lift the entire clump from underneath. If the soil is heavy clay, the clump might be quite heavy, so take your time. Shake off the excess soil gently.
What to do next:
- Cut stalks to 6 inches.
- Attach labels to the stems immediately.
- Use a garden fork to loosen soil in a 12-inch radius.
- Lift the clump from below, avoiding the neck area.
Step 3: Cleaning and Curing
Once the tubers are out of the ground, they need a bit of cleaning before they can go into storage. For a closer look at tuber anatomy, see Dahlia Tubers: What You Need to Know.
To Wash or Not to Wash?
There are two schools of thought on cleaning. Some gardeners prefer to use a garden hose to wash every bit of soil off the tubers. This makes it much easier to see the "eyes" and check for any signs of rot or insect damage.
Other gardeners, especially those with very light, sandy soil, prefer to just brush off the loose dirt and leave the rest. If you have heavy clay soil, washing is usually necessary because clay holds onto moisture, which can lead to rot during the winter. If you do wash them, be gentle with the water pressure so you don't damage the skin.
Curing the Tubers
"Curing" simply means letting the tubers dry out and toughen up before they are packed away. Place your cleaned clumps in a frost-free, shaded area with good air circulation, like a garage or a covered porch.
Avoid placing them directly on a concrete floor, as concrete can pull too much moisture out of the tubers and cause them to shrivel. Instead, lay them on cardboard, newspaper, or wooden pallets. Let them dry for 24 to 48 hours. They should feel dry to the touch, and any remaining soil should be crumbly and easy to brush away.
Step 4: To Divide Now or Wait Until Spring?
One of the most common questions we hear is whether you should divide the clump into individual tubers in the fall or wait until the spring. Both methods work, and the choice often depends on your available storage space.
Dividing in the Fall
If you have a lot of dahlias and limited space, dividing in the fall is a great option. Individual tubers take up much less room than large clumps. Additionally, the tubers are softer and easier to cut in the fall. The downside is that it can be very difficult to see the "eyes" on a freshly dug tuber, and if you cut a tuber that doesn't have an eye, it will never grow.
Dividing in the Spring
Many home gardeners find it easier to store the entire clump whole. In the spring, after the tubers have been in storage, the eyes will often begin to swell or even sprout, making it much easier to see exactly where to make your cuts. The downside is that storing whole clumps requires more packing material and larger containers. If you prefer perfectly round blooms, browse our PomPon Dahlias.
How to Identify a "Viable" Tuber
For a dahlia tuber to grow into a plant, it must have three things:
- The Body: The fat part of the tuber that holds the energy and food.
- The Neck: The narrow part connecting the body to the crown.
- The Eye: A small bump located on the crown (where the neck meets the old stem).
If any of these parts are missing or damaged, the tuber is unlikely to grow. When dividing, always use a clean, sharp knife or garden snips. We recommend dipping your tools in a 10% bleach solution or wiping them with alcohol between plants to prevent the spread of soil-borne diseases.
Step 5: Choosing Your Storage Method
The goal of storage is to keep the tubers in a "Goldilocks" state: not too cold (freezing kills them), not too warm (which causes them to sprout too early or rot), not too wet (rot), and not too dry (shriveling).
Ideal Temperature and Humidity
The perfect storage temperature is between 40°F and 50°F. Most unheated basements, crawl spaces, or insulated garages stay within this range. If the temperature stays consistently above 60°F, the tubers will think it's spring and start to grow.
Humidity should be around 80%. Since most homes are much drier than that in the winter, we use packing materials to help regulate the moisture around the tubers.
Storage Containers and Media
At Longfield Gardens, we suggest several different materials that work well for home storage:
- Vermiculite: This is often the top choice for enthusiasts. It holds just enough moisture to keep tubers from shriveling but is sterile and doesn't encourage rot.
- Peat Moss: A classic choice. It’s slightly acidic, which can help prevent fungal growth. Make sure it is slightly damp (like a wrung-out sponge) before packing.
- Wood Shavings: Often sold as pet bedding, these are inexpensive and provide good insulation.
- Cardboard Boxes or Plastic Bins: Use cardboard if your storage area is slightly damp, as it allows for some air exchange. Use plastic bins (with the lids slightly ajar) if your storage area is very dry.
The Packing Process
- Start with a 2-inch layer of your chosen medium (like vermiculite) at the bottom of the container.
- Place your tubers or clumps inside, making sure they aren't touching each other. If one tuber starts to rot, you don't want it to spread to the others.
- Cover the tubers with more medium until they are completely buried.
- Label the outside of the box with the varieties inside.
Key Takeaway: Success comes from maintaining a temperature of 40–50°F and using a packing medium like vermiculite to prevent shriveling.
Step 6: Winter Maintenance
Storing dahlias isn't a "set it and forget it" task. You should check on your tubers about once a month throughout the winter. This only takes a few minutes but can save your entire collection. And if you ever have a concern about product quality, our 100% Quality Guarantee is there for peace of mind.
Checking for Rot
If you see a tuber that has turned soft, mushy, or smells bad, remove it immediately and throw it away. Rot can spread quickly through a storage bin. If only a small part of a large clump is rotting, you can sometimes cut away the bad part, let the wound dry, and repack the rest.
Checking for Shriveling
If the tubers look wrinkled or feel light and "corky," they are losing too much moisture. Use a spray bottle to lightly mist the packing medium with water. You don't want it to be wet—just a tiny bit of moisture is enough to stop the shriveling.
Common Myths and Internet Hacks
In the world of gardening, there are many "hacks" that promise perfect results. One common suggestion is to wrap individual tubers tightly in plastic wrap (the Saran wrap method). While some gardeners have success with this, it can be risky for beginners. If there is any trapped moisture or a tiny bit of rot on the tuber when it’s wrapped, the plastic will seal it in and destroy the tuber quickly. Using a breathable medium like vermiculite or peat moss is generally much safer and more reliable.
Another myth is that you must use fungicide powder on every cut. While professional growers sometimes do this, it isn't strictly necessary for the home gardener. If you allow your tubers to "cure" and dry properly for a day or two after cutting, they will form a natural callous that protects them from infection.
Preparing for Spring
When the days begin to lengthen and the ground starts to thaw, it’s time to check your tubers one last time. In late March or early April, you can move your storage bins to a slightly warmer spot to "wake them up." This is the best time to divide any clumps you stored whole, as the eyes will be clearly visible.
Don't be in a rush to plant them in the ground. Dahlias love warm soil. Wait until the danger of frost has passed and the soil temperature reaches about 60°F. In most parts of the US, this is the same time you would plant tomatoes. If you’re ordering fresh tubers for spring, our Shipping Information page explains how order timing works by zone.
Summary of the Process
Saving your dahlias is a rewarding cycle that connects one gardening season to the next. It transforms a single summer purchase into a lifetime of blooms. If you want a colorful mix for next season, browse the Dahlia Decorative Summer Jewels Mix.
- Wait for the frost to signal dormancy.
- Cut and label your plants to stay organized.
- Dig carefully with a fork to protect the fragile necks.
- Clean and dry the tubers for 24–48 hours.
- Pack in a medium like vermiculite or peat moss.
- Store in a cool, dark place between 40°F and 50°F.
- Check monthly for rot or shriveling.
Following these simple steps will give you the best chance of success. Gardening is all about learning as you go, and even if you lose a few tubers your first year, you will gain the experience to grow even more beautiful flowers in the future. We are here to help you every step of the way with quality plants and practical advice. For more tips on growing and caring for your favorite flowers, you can explore our other guides on the Longfield Gardens website.
"Digging dahlias is more than just a chore; it’s the bridge between the beauty of the past season and the promise of the next. Getting the basics of temperature and moisture right is the key to a successful spring."
FAQ
Can I store dahlia tubers in the refrigerator?
While a refrigerator is cool, it is often too cold and too dry for dahlia tubers. Most refrigerators are kept around 35-37°F, which is dangerously close to freezing for a tender tuber. Additionally, fruits and vegetables in the fridge can release ethylene gas, which can damage the tubers’ ability to sprout. A cool basement or garage is usually a much better choice. For a broader overview of growing and caring for them, see All About Dahlias.
What if my tubers look shriveled in the spring?
Slight shriveling is normal and usually isn't a cause for concern. As long as the tuber still feels firm (like a carrot that’s been in the fridge a little too long) rather than hollow or mushy, it will likely grow. You can soak shriveled tubers in a bucket of room-temperature water for an hour or two before planting to help them rehydrate.
How do I know if a tuber is dead or rotten?
A dead or rotten tuber will feel mushy or "squishy" when you squeeze it. It may also have a dark, discolored appearance or a sour, unpleasant smell. If you cut into a healthy tuber, the inside should be white or creamy, similar to a potato. If the inside is brown or black, the tuber has rotted and should be discarded.
Do I have to wash the dirt off before storing?
It is not strictly required to wash them, but it is highly recommended if you have heavy or wet soil. Soil can harbor fungi and pests, and it can also trap moisture against the skin of the tuber, leading to rot. If your soil is very dry and sandy, you can often just shake the clumps clean, but washing provides a better opportunity to inspect the health of the tuber. For a planting refresher, read How to Plant and Grow Dahlia Tubers.