Introduction
There is nothing quite like the late-summer explosion of color that dahlias bring to the garden. Whether you love the massive, dinnerplate-sized blooms or the tidy, pompon dahlias, these plants often become the stars of the show. As the season winds down and the first hints of frost appear, many gardeners wonder if they can keep that beauty going for another year.
The good news is that saving your dahlias is a wonderful way to grow your collection without starting from scratch every spring. At Longfield Gardens, we enjoy helping gardeners find simple ways to make their landscapes even more beautiful. Learning how to over-winter these plants is one of the most rewarding skills you can add to your gardening toolkit.
This guide will walk you through the process of saving your plants, from the first frost to spring planting. It is designed for anyone who wants to preserve their favorite varieties and enjoy even bigger, better blooms next season. Saving your dahlias is an achievable and enjoyable project that connects you to the rhythm of the seasons.
Understanding Dahlia Tubers
Before we dive into the steps for saving your plants, it helps to know exactly what you are working with. While many people ask, "Can you save dahlia bulbs?" the plants actually grow from tubers. Tubers are thickened, underground parts of the stem that store energy and nutrients for the plant.
A dahlia tuber looks a bit like a fingerling potato or a bunch of carrots. Unlike a true bulb, which is a complete plant in a tiny package, a dahlia tuber needs a specific part called the "eye" to grow. These eyes are located on the neck of the tuber, right where it meets the old stem. When you save your dahlias, your goal is to protect these tubers and their precious eyes through the cold winter months.
Dahlias are native to the warm climates of Mexico and Central America. Because of this, they are not naturally equipped to survive freezing temperatures. In most parts of the United States, leaving them in the ground over winter would result in the tubers freezing and rotting. By lifting them and storing them indoors, you are simply giving them a safe, cozy place to sleep until the warm weather returns.
Key Takeaway: Dahlias grow from tubers, not true bulbs. Because they are sensitive to freezing temperatures, they must be moved to a frost-free environment to survive the winter in most regions.
When Is the Right Time to Dig?
Timing is one of the most important factors when it comes to saving your dahlias. If you dig them up too early, the tubers may not have stored enough energy to sprout next year. If you wait too long, a deep freeze could damage the tubers underground.
The best signal to look for is the first frost. You will notice that after a light frost, the vibrant green foliage of your dahlias will turn black or dark brown. This might look a bit sad at first, but it is actually a helpful sign from nature. This "blackening" tells the plant to stop sending energy to the leaves and flowers and instead focus everything on the tubers.
We recommend waiting about a week or two after this first frost before you start digging. This brief waiting period allows the tubers to "cure" slightly in the ground and encourages the eyes to become more visible. However, if your local weather forecast predicts a hard, deep freeze where the ground might freeze several inches down, it is better to dig them up a little sooner.
What to Do Next
- Watch the weather for the first light frost in your area.
- Once the foliage turns dark, leave the plants in the ground for 7 to 14 days.
- Prepare your storage supplies (boxes, labels, and packing material) during this waiting period.
- Check the soil moisture; if it is exceptionally wet, you may want to dig sooner to prevent rot.
Preparing the Plants for Lifting
Once you have waited for the foliage to die back, it is time to prepare the plants for their move. The first step is to cut the stems down. Use a sharp pair of garden pruners or a small saw to cut the main stalks. Leave about 4 to 6 inches of stem protruding from the ground.
These short stems serve two purposes. First, they act as a convenient handle while you are digging. Second, they help you locate exactly where the center of the tuber clump is. Dahlia stems are hollow, so don't be surprised if you see water inside them when you cut.
This is also the most important time to label your plants. Once the flowers are gone and the stems are cut, most dahlia tubers look exactly alike. If you have multiple varieties, use a waterproof marker and a tag to identify each clump. You can tie the tag directly to the remaining stem. Some gardeners even write the variety name directly on the tuber later, but a stem tag is a great first step.
How to Lift Your Tubers Safely
Lifting the tubers is a gentle process. Because dahlia tubers can be quite brittle, you want to avoid snapping them off the main clump. A garden fork is often the best tool for this job because it moves through the soil more easily than a solid shovel, which can accidentally slice through a tuber.
Start by placing your fork about 10 to 12 inches away from the center stem. Pushing the fork straight down into the soil, gently pry upward. Work your way around the plant in a circle, loosening the soil as you go. This "circle" method ensures that you aren't cutting into the tubers that have grown outward from the center.
Once the soil is loose all the way around, reach down and grasp the base of the stems. Gently lift the entire clump out of the ground. Don't worry if there is a lot of soil clinging to the tubers; we will deal with that in the next step. The goal here is to get the clump out in one piece without breaking the narrow "necks" where the tubers connect to the stem.
Key Takeaway: Use a garden fork to lift the soil in a wide circle around the plant. Lifting gently from underneath prevents damage to the tubers and the "eyes" needed for next year's growth.
Cleaning and Curing Your Dahlias
Now that your tubers are out of the ground, they need a little bit of cleaning before they go into storage. Start by gently shaking the clump to remove large chunks of soil. You can use your fingers or a small wooden stick to poke away dirt from the center of the clump.
Some gardeners prefer to wash their tubers with a garden hose. This makes it much easier to see the eyes and check for any signs of damage or rot before they go into storage. If you choose to wash them, use a gentle stream of water. Avoid using high pressure, as you don't want to nick the skin of the tubers.
After cleaning, the tubers must be dried, or "cured." This is a vital step in preventing rot during the winter. Place your tubers in a frost-free, shaded area with good air circulation. An unheated garage, a shed, or a covered porch works well. Turn the clumps upside down (stems pointing down) to allow any water trapped in the hollow stems to drain out.
Let the tubers dry for about one to three days. You want the outside skin to feel dry and firm, but you don't want the tuber itself to start shriveling. Think of it like drying an onion; the outer layer should be dry, but the inside should remain plump and full of moisture.
What to Do Next
- Shake or wash off the excess soil gently.
- Trim off any long, thin "hair" roots that are dangling from the tubers.
- Place the clumps upside down in a protected area to drain and dry.
- Inspect the tubers for any soft spots or damage and trim those parts away with a clean knife.
Choosing the Right Storage Medium
The biggest challenge of saving dahlia bulbs is finding the balance between "too wet" and "too dry." If the environment is too damp, the tubers will rot. If it is too dry, they will shrivel up like raisins and may not have enough energy to sprout in the spring.
To solve this, we use a storage medium. This is a material that surrounds the tubers and helps regulate moisture. There are several common options that work well:
- Peat Moss: This is a very popular choice because it holds just enough moisture while still allowing the tubers to breathe.
- Vermiculite: This lightweight mineral is excellent at regulating moisture and is often used by professional growers.
- Wood Shavings: The kind sold for animal bedding works great. It provides good insulation and prevents the tubers from touching each other.
- Coarse Sand: Sand is heavy but provides a very stable environment. It is less likely to hold excess water than peat moss.
Avoid using airtight plastic containers or bags. Tubers are living things and they need a small amount of oxygen to survive their dormancy. Cardboard boxes, plastic crates with ventilation holes, or even paper bags nested inside a larger box are all excellent choices.
Packing Your Tubers for Winter
When you are ready to pack, start by placing a layer of your chosen storage medium (about 2 inches) at the bottom of your container. Lay your dahlia clumps on top of this layer. It is perfectly fine if the tubers touch each other, but try to give them a little bit of breathing room if possible.
Cover the clumps with more of the storage medium until they are completely buried. If you are using a large box, you can create multiple layers. Just make sure there is plenty of material between each layer to act as a buffer.
If you are saving many different varieties, you can pack them in separate paper bags labeled with the variety name, then place all those bags into a larger cardboard box. This keeps everything organized and makes it easy to find your favorite colors when spring arrives.
Key Takeaway: Store tubers in a breathable container filled with a moisture-regulating material like peat moss or wood shavings. This keeps them plump and prevents rot.
The Ideal Storage Environment
Where you keep your dahlia tubers over the winter is just as important as how you pack them. The "Goldilocks" temperature for dahlia storage is between 40°F and 50°F.
If the temperature drops below freezing (32°F), the water inside the tubers will freeze, causing the cells to burst. This results in a mushy, ruined tuber. On the other hand, if the temperature stays above 60°F, the tubers may think it is time to wake up and start growing, or they may simply dry out too quickly.
Common storage locations include:
- Unheated Basements: These often stay within the perfect temperature range.
- Crawl Spaces: These are usually well-insulated from the extreme cold.
- Attached Garages: If your garage is insulated and doesn't drop below freezing, it can be a good spot. You might want to keep the boxes off the cold concrete floor by placing them on a shelf or a wooden pallet.
Check the temperature of your chosen spot with a simple thermometer. Remember that temperatures can change as the winter gets deeper, so a spot that is perfect in November might get too cold in January.
Checking Your Tubers Mid-Winter
Saving dahlia bulbs isn't a "set it and forget it" task. We recommend checking on your stored tubers about once a month. This small effort can save an entire collection if something starts to go wrong.
When you open your boxes, look for two main things: rot and shriveling.
If you find a tuber that feels soft, mushy, or has visible mold, it is starting to rot. Use a clean knife to cut away the affected part, or remove that entire clump from the box so the rot doesn't spread to the healthy tubers. If the storage medium feels very damp, you might want to replace it with fresh, dry material.
If the tubers look very wrinkled and feel light or "squishy" like a sponge, they are drying out. You can fix this by lightly misting the storage medium with a spray bottle filled with water. You don't want to make it soaking wet—just a tiny bit of humidity is usually enough to stop the shriveling.
What to Do Next
- Set a reminder on your calendar to check your tubers once a month.
- Keep a spray bottle and a clean pair of pruners near your storage area.
- Ensure your labels are still legible and attached.
- If you see early sprouts in late winter, move the tubers to a slightly cooler (but still frost-free) spot to slow them down.
Dividing Tubers: A Quick Overview
While the main goal of saving your dahlias is to keep them alive, you might notice that your clumps have grown much larger than they were in the spring. You can choose to divide these clumps into individual tubers, which will give you many more plants for free.
Some gardeners like to divide in the fall before they pack the tubers away. This saves space in the storage boxes. Others prefer to wait until spring when the "eyes" are easier to see. There is no wrong time, but for beginners, spring is often easier.
When you do decide to divide, remember that every individual tuber must have a piece of the original stem attached to it, because that is where the eye is located. A tuber without an eye will not grow, even if the tuber itself looks perfectly healthy.
Bringing Dahlias Out of Dormancy
As the days get longer and the ground begins to warm, it's time to think about planting again. About 4 to 6 weeks before your last expected frost date, you can pull your dahlia boxes out of storage.
At this point, you may see small sprouts beginning to grow from the eyes. This is an exciting sign that your saving efforts were a success! If you want an early start, you can "pot up" your tubers indoors in containers. If you prefer to plant directly in the garden, wait until the soil has warmed up to at least 60°F and all danger of frost has passed. Dahlias love the sun and well-drained soil, so choose your spot accordingly. The energy you saved in those tubers over the winter will now power a new season of spectacular growth.
Key Takeaway: Start checking for sprouts in early spring. You can plant your saved tubers directly in the garden once the soil is warm and the threat of frost is gone.
Why Some Tubers Don't Make It
Even the most experienced gardeners lose a tuber or two over the winter. It is a natural part of the process, and you shouldn't feel discouraged if it happens. Usually, the cause is one of three things:
- Poor Drainage in the Garden: If the fall was exceptionally rainy, the tubers might have been too wet before they were even dug up.
- Damaged Necks: If a tuber is handled roughly and the narrow neck snaps, the connection to the eye is lost.
- Inconsistent Temperatures: Large swings in temperature during storage can stress the tubers and lead to rot.
By following the simple steps of lifting gently, curing properly, and checking in during the winter, you maximize your chances of success. Each year you save your dahlias, you will learn more about what works best in your specific climate and storage space.
Conclusion
Saving dahlia bulbs is a rewarding tradition that turns a single season of beauty into a lifetime of gardening enjoyment. By understanding the needs of the tubers and providing them with a cool, stable home for the winter, you can grow your dahlia collection without starting from scratch every spring.
At Longfield Gardens, we believe that gardening should be a source of joy and relaxation. Taking these few simple steps in the fall ensures that your garden will be ready to dazzle again next year. Whether you are saving a single sentimental plant or a vast collection, the process is a wonderful way to preserve your favorite colors all year round.
- Wait for the first frost before digging to ensure energy storage.
- Cure tubers for a few days to toughen the skin and prevent rot.
- Store in a breathable medium like peat moss at 40-50°F.
- Check monthly to adjust moisture levels and remove any damaged pieces.
The secret to successfully saving dahlias is simply paying attention to the plant's natural signals. With a little bit of care, those humble tubers will reward you with spectacular blooms year after year.
Ready to expand your collection for next season? We invite you to explore our wide selection of premium dahlia varieties and planning guides to help you create your most beautiful garden yet.
FAQ
Can I leave my dahlias in the ground if I live in a warm climate?
If you live in USDA Hardiness Zone 8 or warmer, you can often leave dahlia tubers in the ground over the winter. However, it is a good idea to cover the area with a thick layer of mulch to protect them from occasional cold snaps and excessive winter rain. In colder zones, lifting and storing them indoors is necessary for the plants to survive. For help checking your area, see the Hardiness Zone Map.
Do I have to wash the dirt off the tubers before storing them?
Washing isn't strictly required, but it is highly recommended. Cleaning the tubers makes it much easier to inspect them for pests, rot, or damage before they go into storage. If you choose not to wash them, make sure to brush off as much dry soil as possible, as soil can harbor moisture and bacteria that lead to rot during the winter.
What should I do if my dahlia tubers look shriveled in February?
Shriveling is a sign that the storage environment is too dry. You can gently mist the storage medium (the peat moss or wood shavings) with a little bit of water to increase the humidity. Be careful not to make the medium soaking wet, as this can cause the tubers to rot; a light dampness is all they need to rehydrate.
Is it okay to store dahlias in a refrigerator?
While a refrigerator stays within the correct temperature range, it is usually not the best place for dahlia storage. Refrigerators are designed to remove humidity, which can cause the tubers to dry out very quickly. Additionally, some fruits release gases that can damage the tubers. A cool basement or insulated garage is generally a much better choice. For shipping timing and order details, see our Shipping Information page.
