Table of Contents
- Introduction
- The Deciding Factor: Your Climate and Zone
- Why We Lift Dahlias (Even in Warmer Zones)
- Timing Your Harvest: The Frost Signal
- How to Lift Your Dahlias Correctly
- Cleaning and Curing for Storage
- Choosing the Right Storage Medium
- Creating the Ideal Storage Environment
- Leaving Dahlias in the Ground (Winterizing)
- Replanting in Spring: The Reward
- Summary of Success
- FAQ
Introduction
As summer fades into autumn, the dahlia garden often puts on its most spectacular show. These vibrant dahlias are the crown jewels of the late-season landscape, offering a final burst of color before the cold sets in. At Longfield Gardens, we want to help you keep that beauty coming back year after year so you can enjoy these stunning flowers every summer.
One of the most common questions we hear as the days grow shorter is whether you really need to go through the process of digging up your tubers. This guide will help you understand if your climate requires lifting, how to do it correctly, and how to store your tubers so they stay healthy until spring. If you're planning ahead for next season, browse our dahlia collections.
The decision to lift your dahlia tubers depends primarily on your local climate and your goals for next year’s garden. While some gardeners can leave them in the ground, many of us find that a little extra care in the fall leads to much bigger rewards in the summer.
The Deciding Factor: Your Climate and Zone
The most important factor in determining if you must lift your dahlias is your USDA hardiness zone. If you aren't sure where you fit, our Hardiness Zone Map can help. Dahlias are native to the high plains of Mexico and Central America, where the ground does not freeze hard. Because they are tender perennials, they cannot survive being frozen solid.
If you live in USDA Zones 3 through 7, the short answer is yes: you generally need to lift your tubers if you want them to survive the winter. In these regions, the ground freezes deep enough to reach the tubers. When the water inside the tuber cells freezes, it expands and destroys the plant tissue, leaving you with a mushy, non-viable mess in the spring. Longfield Gardens uses your zone to time shipments, as explained on our Shipping Information page.
For gardeners in Zone 8, you are in a "gray area." In many years, a thick layer of mulch might be enough to protect the tubers from occasional light freezes. However, an unusually cold winter can still claim your plants. Many people in Zone 8 choose to lift their favorites just to be safe. In Zones 9 through 11, dahlias can typically stay in the ground year-round as long as the soil has excellent drainage.
Key Takeaway: Check your USDA zone first. If you are in Zone 7 or colder, lifting is the most reliable way to ensure your dahlias return next year.
Why We Lift Dahlias (Even in Warmer Zones)
While the freezing cold is the primary reason to dig up dahlias, it isn't the only one. Even if you live in a region where the ground stays relatively warm, there are several benefits to lifting your tubers every autumn.
Avoiding Winter Rot
In many parts of the country, winter is the wettest season. Dahlias are prone to rotting if they sit in cold, soggy soil for months on end. If your garden has heavy clay soil or a spot that collects water, your tubers are at risk of rot even if it never freezes. Lifting them allows you to keep them in a controlled, dry environment.
Preventing Overcrowding
A single dahlia tuber planted in the spring will grow and multiply throughout the summer. By the time autumn arrives, that one tuber has often become a large, heavy clump. If left in the ground for several years, these clumps become overcrowded. This leads to smaller flowers, weaker stems, and plants that are more susceptible to disease because of poor air circulation.
The Opportunity for Division
One of the most rewarding parts of lifting dahlias is the chance to divide them. When you dig up a healthy clump, you can often turn one plant into three, four, or even five new ones. This is the easiest way to expand your garden or share your favorite varieties with friends and neighbors. We find that regular division keeps the plants vigorous and high-performing. If you want the biggest blooms for next season, take a look at our Dinnerplate Dahlias.
Timing Your Harvest: The Frost Signal
Knowing when to start the lifting process is just as important as the technique itself. Many gardeners worry that they need to rush out at the first sign of chilly weather, but patience actually benefits the tubers.
The best time to lift dahlias is after the first "killing frost." This is the frost that turns the green foliage black or dark brown. When the top of the plant dies back, it sends a signal to the tubers to enter dormancy. This transition period allows the tubers to "ripen" and toughen their skins, which helps them survive storage without shriveling up.
Ideally, we recommend waiting about a week or two after the foliage turns black before you start digging. This short wait allows the plant to pull the last of its energy down into the tubers, giving them the best possible start for the following year. However, if your long-term forecast shows the ground is about to freeze hard, don't wait—get them out of the ground. For a fuller seasonal calendar, see When Do Dahlias Grow?.
- Wait for the foliage to turn black.
- Allow 7–14 days for the tubers to ripen if weather permits.
- Lift before the ground itself freezes solid.
How to Lift Your Dahlias Correctly
Lifting dahlias is a straightforward process that requires only a few basic tools: a garden fork (preferable over a shovel), a pair of garden snips, and some labels. Using a fork instead of a shovel reduces the risk of accidentally slicing through the tubers.
Step 1: Cutting Back
Start by cutting the stalks down to about 4 to 6 inches above the soil line. This "handle" makes it easier to lift the clump and provides a place to tie your variety label. Removing the bulk of the foliage also makes the workspace much cleaner and helps you see exactly where the crown of the plant is. When you're ready to replant in spring, our How to Plant Dahlias guide walks through the next step.
Step 2: Digging with a Wide Berth
Dahlia clumps can grow surprisingly wide. To avoid damaging the tubers, start digging at least 12 inches away from the main stem. Gently push your garden fork into the soil and rock it back and forth to loosen the earth. Work your way around the entire plant, loosening the soil from all sides before attempting to lift the clump.
Step 3: Gentle Lifting
Once the soil is loose, gently pry the clump upward. Avoid pulling on the stems, as they can break off at the "neck" of the tuber. The neck is the narrow part where the tuber connects to the main stalk, and it is very fragile. If the neck breaks, the tuber will likely not grow next year, as the "eyes" (growth points) are located on the crown right above that neck.
What to do next:
- Clear a space in a garage or shed to let the tubers dry.
- Have your labels ready before you lift multiple varieties.
- Shake off the loose soil immediately after lifting to make cleaning easier.
Cleaning and Curing for Storage
Once your tubers are out of the ground, they need a little preparation before they go into their winter home. Proper cleaning and "curing" are the keys to preventing mold and rot during the long winter months. For a broader care overview, see All About Dahlias.
Cleaning the Tubers
Some gardeners prefer to wash their tubers with a gentle stream of water from a garden hose to remove all the soil. This makes it easier to spot "eyes" and identify any damaged areas. Others prefer to let the soil dry and then gently brush it off. Either method works, provided you are careful not to nick the skin. If you do wash them, it is vital that they dry completely before they are packed away.
Inspection
Take a moment to look over each clump. Use your snips to remove any small, hair-like feeder roots and any tubers that feel soft, mushy, or hollow. Healthy tubers should feel firm, like a fresh potato. If you see any signs of rot (usually a brown or black slimy area), cut it away until you reach clean, white tissue.
The Curing Process
Curing is simply letting the tubers air dry in a protected, frost-free area for a few days. We recommend placing them upside down (stems pointing toward the floor) on a piece of cardboard or a mesh screen. This allows any moisture trapped inside the hollow stems to drain out. Depending on your humidity, this usually takes 2 to 4 days. The skins will toughen up slightly, which is exactly what you want.
Choosing the Right Storage Medium
Finding the "Goldilocks" level of moisture is the biggest challenge of dahlia storage. If the environment is too dry, the tubers will shrivel and die. If it is too wet, they will rot. The storage medium helps regulate this.
Peat Moss or Coco Coir
This is perhaps the most popular choice. It is lightweight and has natural anti-fungal properties. We find that slightly dampening the peat moss before packing the tubers works best. It should feel like a wrung-out sponge—not dripping wet, but not bone-dry either.
Vermiculite
Vermiculite is excellent for maintaining consistent moisture levels. It is a mineral that expands when heated and can hold a great deal of water while still allowing for air circulation. It is a very clean option that many professional growers prefer.
Wood Shavings
Large pine shavings (the kind used for animal bedding) are another affordable and effective option. They provide plenty of air space around the tubers, which helps prevent the spread of rot. However, they can dry out faster than peat moss, so you may need to check them more frequently.
Plastic Wrap (The Saran Wrap Method)
Some gardeners have success by wrapping individual, divided tubers tightly in plastic wrap. This method keeps the tuber’s own moisture locked inside. While it saves space, it requires that the tubers be perfectly clean and dry before wrapping to avoid trapping bacteria.
Creating the Ideal Storage Environment
Where you put your packed tubers is just as important as how you pack them. You are looking for a spot that is dark, cool, and stays consistently between 40°F and 50°F.
The Unheated Basement
A basement that stays cool but never freezes is often the perfect spot. The natural humidity of a basement can also help prevent the tubers from drying out. Avoid placing your storage bins near a furnace or water heater, as the warmth will wake the tubers up too early or dry them out.
The Attached Garage
If your garage is insulated and stays above freezing, it can work well. However, be cautious with garages, as temperatures can fluctuate wildly. Using a simple indoor/outdoor thermometer can help you monitor the space to ensure it doesn't dip below 35°F.
Troubleshooting Your Storage
Check on your tubers once a month. If you notice they are starting to shrivel, give the storage medium a very light misting of water. If you see a bit of surface mold, wipe it off and leave the container open for a day to increase air circulation. If a tuber has turned completely soft, remove it immediately so the rot doesn't spread to its neighbors.
Key Takeaway: Success in storage is all about balance. A monthly "check-in" prevents small issues from becoming big losses.
Leaving Dahlias in the Ground (Winterizing)
If you live in a warmer zone (Zones 8–11) or if you are a gardener in Zone 7 who likes to experiment, you might decide to leave your dahlias in the ground. While this saves labor, it does require some specific "winterizing" steps to improve their chances of survival. If you want to keep shopping for next year, browse our best-selling dahlias.
The Power of Mulch
In the absence of lifting, mulch acts as a blanket for the soil. After the first frost, cut the stems down to the ground. Apply a thick layer of mulch—at least 6 to 12 inches deep—over the site. You can use straw, shredded leaves, or wood chips. This layer helps keep the soil temperature stable and prevents the frost from penetrating deep enough to harm the tubers.
Drainage Fixes
Since winter wetness is the main enemy of dahlias in the ground, some gardeners choose to cover the mulched area with a piece of plastic or an inverted nursery pot. This helps divert heavy winter rains away from the crown of the plant. Just be sure to remove the cover in early spring so the soil can warm up and the new shoots can emerge.
Risks to Consider
Even with the best mulching, leaving tubers in the ground carries risks. Rodents, such as voles, often find dahlia tubers to be a delicious winter snack. Additionally, you miss the opportunity to divide your plants, meaning they may eventually become overcrowded and less productive.
Replanting in Spring: The Reward
The effort of lifting and storing pays off when spring arrives. As the soil warms to about 60°F and the danger of frost has passed, you can bring your tubers out of storage. This is usually the same time you would plant tomatoes in your area. If you want to keep exploring, our Shop All - Spring-Planted Bulbs page is a good place to start.
You may see small pink or white "eyes" starting to sprout on the crowns of your tubers. This is a great sign! It means the tubers are healthy and ready to grow. If you divided them in the fall, they are ready to go straight into the ground. If you stored them in clumps, spring is an excellent time to divide them, as the eyes are much easier to see when they are starting to swell.
At Longfield Gardens, we recommend planting your dahlias in a sunny spot with well-draining soil. If you want more guidance on site selection, see Where Do Dahlias Grow Well?. Dig a hole about 6 inches deep, lay the tuber on its side with the eye pointing up, and cover it with soil. Avoid watering heavily until you see the first green sprouts poking through the ground, as the tuber has enough stored energy and moisture to get started on its own.
Summary of Success
Preserving your dahlias through the winter doesn't have to be a stressful chore. Instead, look at it as a way to protect the beautiful investment you've made in your landscape. Our 100% Quality Guarantee is there to give you added peace of mind. By following a few simple steps, you can ensure a bigger and better display every year.
- Assess your zone: Lift if you are in Zone 7 or colder.
- Time it right: Wait for the first killing frost to ripen the tubers.
- Dig carefully: Use a fork and give the plant plenty of space.
- Dry and pack: Cure for a few days and store in a cool, dark place.
- Check monthly: Ensure the tubers aren't too wet or too dry.
We hope this guide makes the process clear and achievable. Gardening is a journey of learning what works best in your unique backyard. With a little bit of preparation this autumn, you’ll be ready for another season of breathtaking dahlia blooms. If you want a ready-made assortment for next season, High Summer Mix is a colorful place to begin.
FAQ
Can I store dahlia tubers in the refrigerator?
While a refrigerator stays at a good temperature, it is generally not recommended for dahlia storage. Most refrigerators have very low humidity, which will cause the tubers to shrivel quickly. Additionally, ripening fruits and vegetables in the fridge release ethylene gas, which can damage or kill the dormant "eyes" on the dahlia tubers.
What happens if I don't lift my dahlias in a cold climate?
If you live in a region where the ground freezes (Zone 7 and lower) and you do not lift your dahlias, the tubers will almost certainly die. The water within the tubers will freeze, causing the cell walls to burst. In the spring, instead of new growth, you will find only soft, rotten remains where the tubers used to be.
Should I wash the dirt off the tubers before storing them?
Washing is a personal preference. It makes it easier to see the growth eyes and any signs of damage or rot. However, if you do wash your tubers, you must be extremely diligent about letting them dry completely before packing them away. Any lingering moisture between the tubers can lead to mold or rot during storage.
How do I know if a stored tuber is still good in the spring?
A healthy tuber should feel firm to the touch, similar to a potato. If a tuber is slightly shriveled but still firm, it will usually recover once planted. However, if the tuber is mushy, smells bad, or feels completely hollow and dry like a cracker, it is no longer viable and should be discarded.