Introduction
There is nothing quite like the late-summer glory of a dahlia garden. These plants are the heavy hitters of the flower world, producing spectacular blooms in every imaginable color and shape right up until the end of the season. At Longfield Gardens, we know that the only thing better than enjoying these flowers today is knowing you can enjoy them again next year. If you order new tubers, our Shipping Information page explains how orders are timed by hardiness zone. Because dahlias are tender perennials, they cannot survive freezing winter temperatures in most parts of the country.
Taking the time to lift and store your tubers is a rewarding way to preserve your favorite varieties. It allows you to build a personal collection of flowers that get better and more productive with each passing season. If you're ready to add more, browse our new dahlia tubers for next spring. This guide will help you understand exactly when to take in dahlia bulbs and how to prepare them for a cozy winter rest.
Whether you are a seasoned gardener or growing these beauties for the first time, the process is straightforward and satisfying. By following a few simple timing cues from nature, you can ensure your dahlias return to brighten your garden year after year.
The Best Time to Dig Your Dahlias
Knowing when to take in dahlia bulbs—technically called tubers—is all about watching the weather and the plants themselves. For more on how they work, see Dahlia Tubers: What You Need to Know. For most gardeners in the United States, the ideal time to dig is in late autumn. This usually happens between October and November, depending on your local climate and when the first cold snap arrives.
The most common signal that it is time to dig is the first frost. When temperatures drop below freezing at night, the tender foliage of the dahlia will turn from vibrant green to a dark, blackened brown. This might look like the plant is struggling, but it is actually a natural part of the life cycle. This "killing frost" tells the plant that the growing season is over and it is time to enter dormancy.
We recommend waiting about a week to ten days after this first frost before you start digging. This waiting period allows the tubers to "cure" slightly in the ground. During this time, the plant sends its final energy reserves down into the tubers, which helps them toughen their skins for winter storage. If your area stays mild and a frost does not arrive by mid-November, you can simply cut the plants back and begin the process anyway to ensure you get them inside before the ground itself freezes.
Key Takeaway: The ideal window for digging dahlias begins after the first killing frost has blackened the foliage. Waiting about a week after the frost allows the tubers to mature and toughen their skins for better storage.
Understanding the Role of Frost and Dormancy
The frost acts as a biological "reset button" for dahlias. These plants are native to the high-altitude regions of Mexico and Central America, where they experience distinct wet and dry seasons rather than the freezing winters found in the northern United States. In our gardens, we use the cold of autumn to mimic the end of the growing cycle.
When the foliage dies back, the dahlia stops producing new flowers and foliage. This transition is essential for the health of the tuber. If you dig too early while the plant is still actively growing and green, the tubers may be thin-skinned and more prone to shriveling or rotting during the winter months.
However, there is a limit to how long you should wait. While a light frost on the leaves is helpful, you want to avoid letting the ground freeze solid. If the soil around the tubers freezes, the water inside the tubers will expand, causing the cells to burst. This leads to mushy, unviable tubers that will not grow in the spring. Aim to have your tubers out of the ground and in a protected area before the deep, sustained freezes of winter arrive.
Signs the Tubers Are Ready
- Foliage has turned dark brown or black after a frost.
- The stems have become brittle or soft.
- Daytime temperatures are consistently staying below 50°F.
- The calendar shows it is about two weeks past your average first frost date.
Factors That Influence Timing
While the first frost is the gold standard for timing, several other factors can influence when you should take in your dahlia bulbs. Your specific garden conditions play a large role in how the plants react to the cooling weather.
Soil Drainage and Moisture
If your autumn has been exceptionally wet, you may want to dig your dahlias a bit earlier than usual. For a deeper look at site conditions, see What Soil Do Dahlias Grow Best In?. Saturated soil can lead to tuber rot, especially as the plants go dormant and stop drawing water from the ground. If you see a week of heavy rain in the forecast and your plants are already starting to fade, it is often better to lift them while the soil is still manageable rather than waiting for a frost.
Regional Climate Differences
In the northernmost states or high-altitude areas, the growing season is short. You might find that your dahlias are still in full bloom when the first hard freeze is predicted. In these cases, you can cut the plants back manually and dig them immediately. In the southern United States (Zones 8 and warmer), the ground rarely freezes deep enough to damage the tubers. If you're not sure which zone you live in, our Hardiness Zone Map can help. In these warm regions, you might choose to leave them in the ground with a thick layer of mulch, though many gardeners still prefer to lift and divide them every few years to maintain plant vigor.
Variety Variations
Some dahlia varieties are naturally more robust and produce large, thick-skinned tubers that handle the transition easily. Others, like certain delicate pompon or bedding dahlias, may produce smaller, more fragile tubers. If you want a tighter bloom form for next season, browse our PomPon Dahlias. If you have a variety you particularly love, err on the side of caution and get it into storage as soon as the foliage shows signs of decline.
How to Dig Dahlias Without Damage
Once the timing is right, the process of lifting the tubers requires a gentle hand. The "necks" of dahlia tubers—the narrow part where the tuber connects to the main stem—are quite fragile. If the neck breaks, the tuber often loses its ability to sprout next year because the "eyes" (growth buds) are located at the base of the stem.
Start by cutting the dahlia stalks down to about 4 to 6 inches above the soil line. This remaining bit of stem acts as a handle and helps you identify where the center of the clump is located. It also makes the clump much easier to manage once it is out of the ground.
Use a garden fork rather than a shovel if possible. A fork is less likely to slice through the tubers as you work. Begin digging about 10 to 12 inches away from the main stem. This ensures you are outside the reach of the tuber clump. Gently pry the soil upward from all sides of the plant to loosen the root ball. Once the soil is loose, you can lift the entire clump by the base of the stem. If you'd like a spikier bloom form next season, our Cactus Dahlias collection is a good place to look.
What to do next:
- Clear away any support stakes or labels before you start digging.
- Loosen the soil in a wide circle around the plant to avoid cutting tubers.
- Lift the clump gently by the stems and shake off the loose excess soil.
- Keep your labels attached to the stems immediately so you don't lose track of varieties.
Cleaning and Preparing Tubers for Storage
Once the tubers are out of the ground, they need a bit of preparation before they go into their winter crates. There are two main schools of thought regarding soil: some gardeners prefer to wash it all off, while others leave a bit of soil on to help protect the tubers. If you want another classic form for your summer display, our Decorative Dahlias collection offers plenty of options.
If your soil is heavy clay, washing is usually best. Use a gentle stream of water from a garden hose to rinse away the dirt. This allows you to inspect the tubers for any signs of damage or pests. If your soil is sandy and falls away easily, a simple shake may be all they need.
After cleaning, it is vital to let the tubers dry. This process is called curing. Place the clumps in a frost-free, well-ventilated area—like a garage or a basement—for 1 to 3 days. Do not leave them in direct sunlight or in a spot with high winds, as they can dry out too much. You want the surface of the tuber to feel dry to the touch and any cut stems to begin to callus over.
To Divide or Not to Divide?
Many gardeners wonder if they should divide their dahlia clumps in the fall or wait until spring.
- Fall Division: The tubers are softer and easier to cut. It saves storage space and allows you to see the "eyes" more clearly on some varieties.
- Spring Division: The "eyes" are often much easier to see in the spring as they begin to swell. There is also less risk of the individual tubers drying out over winter if they stay in a large clump.
For beginners, we often suggest keeping the clumps intact over the winter and dividing them in the spring. This is a simple, low-stress way to ensure the tubers stay hydrated.
Creating the Ideal Winter Storage Environment
The goal of winter storage is to keep the tubers dormant, cool, and plump. If the storage area is too warm, the tubers will try to grow. If it is too dry, they will shrivel up like raisins. If it is too damp, they will rot.
The ideal temperature for storing dahlia tubers is between 40°F and 50°F. An unheated basement, a root cellar, or a cool closet in a garage usually works well. Avoid areas that drop below freezing, such as an uninsulated shed, as this will kill the tubers.
We find that packing tubers in a medium helps regulate moisture levels. Common choices include:
- Peat Moss: Excellent for holding just the right amount of moisture.
- Vermiculite: Great for aeration and moisture control.
- Wood Shavings: A clean, easy-to-handle option that provides good airflow.
- Newspaper: Simple and effective for wrapping individual tubers or clumps.
Place a layer of your chosen medium in a cardboard box, plastic bin (with the lid slightly ajar), or a wooden crate. Nestle the tubers inside and cover them with more medium. If you use plastic bins, ensure there is some airflow so moisture doesn't build up and cause mold.
Key Takeaway: Successful storage requires a balance of cool temperatures (40-50°F) and moderate humidity. Using a packing medium like peat moss or wood shavings helps prevent the tubers from drying out or rotting.
Troubleshooting Common Storage Issues
Even with the best timing, it is important to check on your dahlias once or twice during the winter. This allows you to catch any issues before they spread to the whole collection. At Longfield Gardens, we recommend a "mid-winter checkup" around January or February.
If you open your storage container and find that the tubers look shriveled or wrinkled, they are losing too much moisture. You can lightly mist the packing medium with water to add a bit of humidity. Be careful not to make the medium soggy; you just want it to be slightly damp to the touch.
If you find a tuber that feels mushy or has visible fuzzy mold, remove it immediately. Rot can spread quickly from one tuber to another. Cut away any affected parts of a clump with a clean, sharp knife and let the healthy portion dry before putting it back. If an entire clump is soft, it is best to discard it to protect the rest of your plants.
Gardening is a learning process, and every storage space is a little different. If your tubers are too dry one year, try a different packing medium or a tighter-fitting lid the next. If they are too wet, try a more breathable container like a cardboard box.
When to Bring Dahlias Back Out
The cycle comes full circle in the spring. Once the threat of frost has passed and the soil has warmed to about 60°F, you can bring your tubers out of storage. This is the perfect time to divide large clumps and share them with friends or expand your own garden. If you're planning a bigger bloom show next season, our Dinnerplate Dahlias are a great place to start.
In many regions, this happens in late April or May. If you want a head start on the season, you can "wake up" your dahlias indoors about 4 to 6 weeks before your last frost date. Simply pot them up in some light potting soil and place them in a sunny window or under grow lights. For step-by-step planting advice, see How to Plant and Grow Dahlia Tubers. By the time the weather is warm enough for outdoor planting, you will have sturdy little plants ready to go.
Remember that dahlias are patient. If you aren't sure if the soil is warm enough, it is usually better to wait an extra week. Planting in cold, wet soil can lead to rot before the plant even has a chance to sprout. When the ground feels warm to the touch and the trees are leafing out, it is time to get those tubers back into the earth.
Summary of the Dahlia Lifting Process
Managing the end of the dahlia season is a simple task that yields big rewards. By paying attention to the weather and following a few basic steps, you can keep your garden growing year after year.
- Watch the Weather: Wait for the first frost to blacken the foliage.
- Wait to Dig: Give the tubers about a week in the ground after the frost to cure.
- Dig Gently: Use a garden fork and start far enough away from the stem to avoid damage.
- Dry and Clean: Let the tubers air dry for a few days in a frost-free area.
- Pack Carefully: Store in a cool, dark place (40-50°F) using a medium like peat moss or shavings.
- Check In: Inspect your tubers once or twice during the winter to adjust moisture levels.
Conclusion
Taking in dahlia bulbs is a simple and satisfying way to transition your garden from the exuberance of summer to the quiet rest of winter. While the process requires a bit of effort, the payoff is a beautiful, thriving garden that returns with even more vigor the following summer. At Longfield Gardens, our goal is to help you feel confident in every step of the journey, from the first sprout to the final harvest of the year. Our 100% Quality Guarantee is part of that promise.
By timing your digging with the natural cues of the first frost and providing a stable winter home, you are protecting the heart of your garden. Gardening is a rewarding cycle of growth and rest, and mastering the art of winter storage is one of the most practical skills a flower lover can have. If you love oversized blooms, the Ball Dahlias collection is another strong choice for next season.
We look forward to hearing about your dahlia successes. When spring arrives, you'll be ready to start the cycle again with a healthy, vibrant collection of tubers.
FAQ
Can I dig up my dahlias before the first frost?
Yes, you can dig them up before the first frost if your growing season is very short or if you need to clear the garden bed early. However, waiting for the frost or at least until the foliage begins to yellow naturally ensures the tubers are fully mature and have thicker skins, which helps them survive longer in winter storage.
How long can dahlia tubers stay in the ground after it freezes?
Dahlia tubers can handle a light frost that kills the leaves, but they cannot survive if the ground itself freezes. You should aim to dig them up within two weeks of the first frost. If a deep freeze is predicted that might freeze the top few inches of soil, you should lift the tubers immediately to prevent them from turning to mush.
What if my dahlia foliage doesn't turn black?
In some milder climates, the foliage may only turn yellow or stay green late into the fall. If you haven't had a killing frost by mid-November, it is a good idea to cut the plants back manually. Wait about a week after cutting the stems to allow the tubers to toughen up, then proceed with digging and storing as usual.
Do I need to wash the dirt off the tubers before storing them?
Washing is not strictly necessary, but it is often helpful. Removing the soil allows you to see the "eyes" and check for any signs of rot or damage. If you have very light, sandy soil, you can simply shake the dirt off. If you do wash them, make sure they are completely dry before you pack them away for the winter to prevent mold.
