Introduction
The end of the gardening season often feels like a grand finale, especially when your dahlias have been the stars of the show. There is a special kind of magic in watching these plants transform from small, humble tubers into the lush, dinnerplate dahlias that define a late-summer landscape. At Longfield Gardens, we believe that the joy of growing dahlias doesn’t have to end when the first frost arrives.
Lifting and storing your tubers is a rewarding way to preserve your favorite varieties and multiply your garden's beauty for the following year. While it might seem like a complex task at first, it is actually a straightforward process that any home gardener can master. This guide will walk you through everything you need to know, from timing your harvest to keeping your tubers cozy all winter long.
By following a few simple steps, you can ensure your favorite flowers return even stronger and more spectacular next season. Learning how to lift dahlia tubers correctly is the key to a lifetime of beautiful, home-grown blooms.
Why Lifting Your Dahlia Tubers Is Worth the Effort
Dahlias are tender perennials, meaning they are native to warm climates where the ground never freezes. In most parts of the United States, specifically USDA hardiness zones 3 through 7, the cold winter soil will cause dahlia tubers to freeze and eventually rot. Lifting them is the only way to keep them alive until spring.
Beyond simple survival, there are several wonderful benefits to digging up your tubers. First, it is an incredible way to grow your collection for free. A single dahlia tuber planted in the spring will often produce a large clump of five to twenty new tubers by autumn. When you lift and divide these clumps, you suddenly have enough plants to fill an entire border or to share as cut flowers with friends and neighbors.
Additionally, lifting your tubers allows you to take stock of your garden's health. You can inspect the root systems, ensure they are free of pests, and select only the strongest specimens for next year. It also gives you the flexibility to rearrange your garden layout each spring, trying out new color combinations or moving your favorite varieties to a more prominent spot.
Identifying Your USDA Hardiness Zone
Knowing your USDA hardiness zone is the first step in planning your winter dahlia care. This system helps gardeners understand which plants can survive the winter in their specific climate. If you live in zones 8 through 11, you may be able to leave your dahlias in the ground with a thick layer of mulch for protection. However, in cooler zones, lifting is necessary.
- Zones 3–5: Expect to lift tubers in late September or early October.
- Zones 6–7: Most gardeners lift in late October or early November.
- Zones 8 and warmer: You can often leave them in the ground, though many gardeners still lift and divide them every few years to keep the plants healthy and productive.
If you are unsure of your zone, your local cooperative extension service is an excellent resource. Regardless of your zone, paying attention to your local weather forecast is the most reliable way to time your harvest.
When to Lift: Watching for the Frost Signal
Timing is one of the most important factors when learning how to lift dahlia tubers. You want to give the tubers as much time as possible to mature, but you must get them out of the ground before a deep freeze hits the soil.
The best time to start the process is immediately after the first killing frost. A light frost might only nip the edges of the leaves, but a hard frost will turn the entire plant black or dark brown. This "blackening" is a signal to the plant that it is time for its winter nap, also known as dormancy. When the foliage dies back, the plant stops sending energy into leaves and flowers. Instead, it directs all its remaining energy down into the tubers, helping them "cure" and toughen up for storage.
Many experienced gardeners wait about one to two weeks after the foliage turns black before digging. This short waiting period allows the tubers to develop a thicker skin, which helps prevent them from drying out or shrivelling during the winter months. However, if your soil is very wet or if a deep, ground-freezing cold snap is predicted, it is better to dig them up a bit sooner.
Gathering Your Essential Tools
Having the right tools on hand will make the job much easier and help prevent accidental damage to the fragile tubers. You likely already have most of these in your garden shed.
- Garden Fork or Pitchfork: This is the most important tool. A fork is much better than a shovel or spade because it is less likely to slice through the tubers as you lift them.
- Hand Pruners or Loppers: These are for cutting back the heavy, woody stems.
- Garden Hose with a Spray Nozzle: You will need this to wash the soil away from the clumps.
- Labels and a Permanent Marker: Do not skip this step! Once the tubers are out of the ground, they all look very similar. Use waterproof labels or flagging tape to mark each variety.
- Containers for Storage: Cardboard boxes, plastic bins (not airtight), or wooden crates all work well.
- Storage Medium: You will need something to surround the tubers, such as peat moss, vermiculite, or wood shavings.
Key Takeaway: Using a garden fork instead of a shovel is the safest way to lift tubers without cutting into them. Always have your labels ready before you start digging to avoid mixing up your varieties.
Step 1: Cutting Back the Foliage
Once the frost has turned your dahlias brown, your first task is to clear away the top growth. Use your pruners or loppers to cut the main stems down to about four to six inches above the soil line.
This short section of stem acts as a "handle" for the rest of the lifting process. It makes it much easier to move the heavy clumps around without putting too much pressure on the delicate "necks" where the tubers attach to the stem.
Be aware that dahlia stems are often hollow and can hold a surprising amount of water. If you have time, you can leave these cut stems in the ground for a few days to allow some of that moisture to drain away. This reduces the weight of the clump and can help prevent rot later on.
Step 2: Digging and Lifting the Clumps
This is the most physical part of the process, but it is also the most exciting. You are finally seeing what has been happening underground all season.
Start by clearing away any mulch or debris from the base of the plant. This helps you see exactly where the stems are. Next, take your garden fork and insert it into the soil about twelve inches away from the main stem. It is better to give the plant too much room than too little. Dahlia tubers can spread out quite far horizontally, and you want to avoid "forking" a beautiful tuber.
Gently push the fork into the soil and lean back to loosen the earth. Move around the plant in a circle, loosening the soil from all sides. Once the ground is soft and the clump feels loose, gently lift the entire mass of tubers upward from underneath. For a broader planting refresher, see our How to Plant and Grow Dahlia Tubers guide.
If the clump is very large and heavy, resist the urge to pull it up by the stem. Pulling on the stem can snap the necks of the tubers. A tuber with a broken neck is usually unable to grow next year, as the connection to the "eye" has been severed. Instead, keep using the fork to support the weight of the clump from below until it is fully free of the soil.
Step 3: Cleaning and Rinsing
Once the tubers are out of the ground, you will likely have a large ball of soil attached to the roots. While some gardeners prefer to leave the soil on until spring, most find that cleaning them now makes for much better storage. Soil can harbor pests and moisture-loving fungi that may cause rot.
Gently shake the clump to remove large chunks of loose dirt. If your soil is heavy clay, you may need to use your fingers or a small wooden stick to carefully poke out the soil from between the tubers.
Next, use your garden hose to rinse the tubers thoroughly. A gentle spray is usually enough. Your goal is to get the tubers clean enough so that you can see the "necks" and the "crown" (the area where the tubers meet the stem). For a closer look at dahlia tuber anatomy, this is the part that matters most.
After rinsing, turn the clumps upside down. This is a crucial step. By resting the clump on its stems, you allow any water trapped inside the hollow stalks to drain out. If this water stays inside the stem, it can travel down to the crown and cause the entire clump to rot during the winter.
Step 4: Inspecting and Air Drying
After the tubers are clean and drained, they need a short period of air drying before they go into their winter storage containers. Move them to a frost-free, shaded area with good air circulation. A garage, garden shed, or a covered porch is ideal.
Avoid placing them in direct sunlight, which can cause the tubers to shrivel too quickly. Let them sit for twenty-four to forty-eight hours. During this time, the skin will continue to toughen up, and any small nicks or cuts from the digging process will have a chance to "callus" over. For more on the growing season that leads up to this point, see All About Dahlias.
While they dry, take a moment to inspect each clump. Look for:
- Soft Spots: If a tuber feels mushy or smells bad, it is likely rotting. Cut it away immediately to prevent the rot from spreading to healthy tubers.
- Pests: Look for signs of insect damage or hitchhikers.
- Damaged Necks: If a tuber is hanging by a thin thread or the neck is clearly snapped, it is best to remove it now.
What to Do Next:
- Turn the tubers upside down for at least 24 hours to drain the stems.
- Label every clump with its variety name using waterproof materials.
- Inspect for mushy spots and trim them off with clean pruners.
- Ensure the skin feels dry to the touch but the tuber still feels firm.
Step 5: To Divide or Not to Divide?
One of the most common questions we hear is whether you should divide your dahlia clumps in the fall or wait until the spring. Both methods have their fans, and the right choice depends on your preference.
Dividing in the Fall:
- Pros: The tubers are softer and much easier to cut. You also save space in storage because you aren't storing the "mother" tuber or any damaged pieces.
- Cons: It can be very difficult to see the "eyes" (the small bumps that will become next year's stems) in the fall. If you cut a tuber and don't include an eye, it won't grow.
Dividing in the Spring:
- Pros: The eyes are much more prominent and often already starting to sprout, making it very easy to see where to cut.
- Cons: The tubers become very tough and "leathery" over the winter, requiring a very sharp knife and more physical effort to separate.
For beginners, we often recommend waiting until spring to do the final division. For a broader overview, see our All About Dahlias guide. However, if your clumps are massive and difficult to handle, you can always cut them into two or three smaller sections in the fall and do the fine-tuning in the spring.
Understanding the Anatomy of a Tuber
If you do choose to divide your dahlias, you must ensure that every piece you save has three specific parts. Think of it like a puzzle where all three pieces are required for the plant to "turn on" in the spring.
- The Tuber: This is the fleshy part that looks like a potato or a carrot. It holds the energy and food for the plant.
- The Neck: This is the narrow part that connects the tuber to the main stem.
- The Eye: This is the most critical part. The eye is found on the "crown" (the piece of the main stem at the top of the neck). If you cut off a tuber but don't get a piece of that crown with an eye, the tuber will grow roots but never produce a stem or flowers.
Eyes look like tiny, pimple-like bumps. In the fall, they can be almost invisible, but by spring, they often look like small green or purple buds.
Step 6: Preparing for Storage
Once your tubers are dry and inspected, it is time to pack them away. The goal of storage is to keep the tubers dormant, cool, and just moist enough that they don't turn into "raisins," but dry enough that they don't rot. If you need more details on timing and transit for future orders, see our Shipping Information.
Start with a breathable container. Cardboard boxes are a favorite because they allow for some air exchange. If you use plastic bins, do not put the lids on tightly; leave them cracked or drill small holes in the sides for ventilation.
Place a two-inch layer of your chosen storage medium at the bottom of the box. Common choices include:
- Peat Moss: Excellent at regulating moisture but can be dusty.
- Vermiculite: A sterile mineral that holds moisture well and is very easy to use.
- Wood Shavings: Often used for animal bedding, these provide great air circulation.
- Dry Sand: A traditional method that is very stable but makes the boxes quite heavy.
Lay your tubers or clumps on top of the medium. Try to keep them from touching each other. This is a safety measure; if one tuber starts to rot, it won't be able to easily pass that rot to its neighbor. Cover the tubers with another layer of the medium until they are completely buried.
Step 7: Finding the Perfect Winter Home
The location where you store your dahlia boxes is just as important as how you pack them. Dahlias need a "Goldilocks" environment: not too hot, not too cold, but just right.
The ideal temperature range is between 40°F and 50°F. If the temperature stays above 60°F, the tubers may think it is spring and start to sprout too early. If the temperature drops below 32°F, the tubers will freeze, and the cells will burst, leading to a mushy, dead plant.
Good storage locations often include:
- An unheated basement or crawlspace.
- An attached garage that stays above freezing.
- A cool closet in a mudroom or utility room.
Keep your boxes off the floor, especially if the floor is concrete, as this can draw moisture or cold into the box. Placing them on a shelf or a wooden pallet is a simple way to keep them safe.
Step 8: Winter Monitoring and Care
Many gardeners make the mistake of "setting and forgetting" their dahlia tubers. To ensure the highest success rate, it is a good idea to check on your tubers about once a month throughout the winter. This allows you to catch small issues before they become big problems.
When you open a box, feel a few of the tubers. They should feel firm, like a fresh potato.
- If they feel shrivelled or wrinkled: This means your storage environment is too dry. Use a spray bottle to lightly mist the storage medium (not the tubers directly) with a little water. This will raise the humidity in the box.
- If you see mold or soft spots: This means the environment is too damp. Remove any rotting tubers immediately. If the storage medium feels wet, replace it with fresh, dry material and consider moving the box to a spot with better air circulation.
Key Takeaway: A monthly check-up is the best way to prevent total loss. Small adjustments to moisture levels in January can save your entire collection for May.
Common Mistakes to Avoid
Gardening is a journey of learning, and dahlias are very forgiving. However, avoiding these common pitfalls will make your experience much more enjoyable. Longfield Gardens backs its plants with a 100% Quality Guarantee, so you can garden with confidence.
First, never store your tubers in airtight plastic bags. Dahlias are living things, even when dormant, and they need to "breathe" slightly. Airtight bags trap moisture and almost always lead to rot.
Second, be careful with your labels. Paper tags can disintegrate if they get damp. Using a permanent marker directly on the skin of a dry tuber is a "pro tip" that many dahlia enthusiasts use. Just make sure the tuber is clean and dry before you write on it.
Finally, don't be discouraged if you lose a few tubers over the winter. Even professional growers expect a small percentage of loss due to natural variations in the plants. Focus on the ones that stay healthy and firm; they will be the foundation of your garden next year.
Replanting in the Spring
When the ground warms up and the danger of frost has passed, usually in late April or May, it is time to bring your dahlias back into the light. At this point, you will clearly see the eyes starting to sprout. This is the perfect time to do your final dividing and prepare your planting holes.
We love the feeling of pulling a firm, healthy tuber out of its winter box and seeing that first bit of green growth. It is a promise of the beautiful summer to come. Our team at Longfield Gardens is always here to support you when you are ready to expand your collection or try a new variety, like a tall dinnerplate type.
Conclusion
Lifting dahlia tubers is a timeless gardening tradition that connects the seasons. It turns a one-summer display into a multi-year legacy of color and joy. While it takes a little bit of time in the autumn, the rewards—more plants, healthier flowers, and the satisfaction of a job well done—are more than worth it.
- Wait for the frost to signal dormancy before you start.
- Lift gently with a fork and protect the tuber necks.
- Dry and store in a cool, dark, frost-free place.
- Check monthly to ensure your tubers stay firm and healthy.
"Saving your own dahlia tubers is one of the most rewarding ways to grow your garden's beauty year after year. It is a simple process that turns a single spring planting into a lifetime of spectacular autumn blooms."
Whether you are a seasoned pro or a smart beginner, we hope this guide makes you feel confident and excited about preserving your dahlias. If you ever have questions or need to add a few more stunning varieties to your garden, we invite you to explore our PomPon dahlias at Longfield Gardens. Happy gardening!
FAQ
Can I leave my dahlias in the ground if I live in a cold climate?
In USDA zones 7 and colder, dahlia tubers will likely freeze and rot if left in the ground during the winter. The soil temperature needs to stay above freezing for the tubers to survive. If you want to keep your favorite varieties, lifting them is the most reliable method for success in northern climates.
What should I do if my dahlia tubers look shrivelled in mid-winter?
Shrivelling is a sign that the storage environment is too dry and the tubers are losing moisture. To fix this, lightly mist the storage medium (like peat moss or wood shavings) with water to increase humidity. You can also move the tubers to a slightly cooler spot, as heat can cause faster moisture loss.
Is it necessary to wash the soil off the tubers before storing them?
While some gardeners leave the soil on, washing the tubers is generally recommended. Cleaning them allows you to inspect for rot, pests, and damaged necks that might lead to problems in storage. It also makes it much easier to see the "eyes" if you plan to divide the clumps before spring.
How do I know if a dahlia tuber is dead?
A dead or non-viable tuber will usually feel very soft, mushy, or completely hollow. If you squeeze it and it gives way easily, it is likely rotten. Additionally, if a tuber is firm but does not have a "neck" or a piece of the "crown" with an eye, it will not be able to grow a new plant in the spring.
