Introduction
Autumn in the garden is a time of both reflection and anticipation. After a summer of vibrant dinnerplate blooms and lush foliage, many gardeners look forward to the rewarding task of lifting and storing their favorite dahlias. While the traditional advice suggests waiting for a hard frost to blacken the leaves, you might find yourself needing to clear your garden beds a little sooner. Whether you have a busy travel schedule or simply want to finish your garden chores while the sun is still warm, you will be happy to know that digging early is a perfectly viable option.
At Longfield Gardens, we believe that gardening should fit into your life, not the other way around. Understanding the needs of your plants allows you to make confident decisions that work for your schedule and your specific climate. This guide is designed for home gardeners who want to know exactly when and how to lift their tubers before the first frost hits. By following a few simple steps, you can ensure your dahlias transition smoothly from the garden to their winter storage.
The short answer is yes, you can dig up dahlia tubers early, provided the plants have had enough time to mature throughout the growing season.
The Short Answer to Early Digging
The most common question we hear as the days grow shorter is whether a frost is strictly necessary for dahlia health. The answer is a resounding no. While a frost serves as a natural "off switch" that tells the plant to go dormant, it is not the only way to prepare a dahlia for its winter rest. You can safely lift your tubers whenever it is most convenient for you, as long as the plants have been growing for at least 120 to 135 days.
In most parts of the United States, this maturity point usually occurs by early to mid-October. By this time, the tubers have spent the entire summer storing energy from the sun and have reached a size and density that allows them to survive the winter. If you planted your dahlias in May or early June, they are likely ready for harvest by the time the autumn air turns crisp.
Why You Might Choose to Dig Early
There are several excellent reasons to get a head start on your dahlia harvest. For many, the primary motivation is comfort. Digging tubers in 60°F weather with dry soil is often more enjoyable than digging in 35°F weather with cold, muddy fingers. When you dig before the first frost, the soil is usually easier to work with and less likely to stick to the tubers in heavy clumps.
Another advantage is the condition of the foliage. Once a hard frost hits, dahlia plants quickly turn into a dark, slimy mass. This can be messy to handle and may obscure the base of the plant. By digging early, you deal with healthy, green stalks that are much easier to cut and manage. Furthermore, if you live in a region with heavy fall rains, lifting the tubers early helps you avoid the risk of them sitting in waterlogged soil, which can lead to rot before you even get them out of the ground.
Key Takeaway: Early digging allows you to work in better weather and cleaner soil, making the process faster and more pleasant.
The Importance of Plant Maturity
While you can dig before a frost, you shouldn't dig too early in the season. Dahlias spend the first half of the summer focused on top growth and flowers. It is only in the latter half of the season—specifically as the days begin to shorten after the summer solstice—that they focus on bulking up their underground tubers.
If you dig your dahlias in August or early September, the tubers may be small, thin, and high in water content. These "immature" tubers are much more likely to shrivel or rot during winter storage. For the best results, aim for that 120-day window. This ensures the tubers have a thick enough skin (the "periderm") to hold in moisture over the long winter months. If your plants are still blooming vigorously and looking healthy, they are still busy feeding those tubers below the surface.
How to Prepare Dahlias for an Early Harvest
When you wait for a frost, the cold weather naturally signals the plant to stop sending energy to the flowers and start focusing on the roots. When you dig early, you have to provide that signal yourself. This is done through a process called "cutting back."
About five to seven days before you plan to dig, use a sharp pair of loppers or garden snips to cut the main stalk of the dahlia down to about six inches above the soil line. This simple act tells the plant that its growing season is over. During this week-long waiting period, several important things happen:
- Skin Toughening: The tubers begin to "cure" in the ground, and their outer skin thickens slightly.
- Eye Development: The "eyes" (the small bumps where next year’s sprouts will emerge) often become more prominent and easier to see.
- Nutrient Transfer: The remaining energy in the lower stalk moves down into the tuber clump.
If you are in a rush, you can cut and dig on the same day, but giving the plants that extra week in the ground usually results in tubers that store much better.
A Step-by-Step Guide to Digging Early
Once your plants have been cut back and allowed to rest for a few days, it is time to lift them. Success in this stage is all about being gentle. Dahlia tubers are connected to the main stem by a narrow "neck." If this neck breaks, the tuber will not grow next year, even if the rest of the tuber looks perfect.
1. Loosen the Soil
Start by placing your shovel or garden fork about 12 inches away from the center of the stalk. Digging too close is the most common cause of sliced or damaged tubers. Gently circle the plant, loosening the soil on all sides. You want to lift the entire root ball rather than prying it up from one side.
2. Lift the Clump
Once the soil is loose, slide your tool deep under the clump. Use a slow, lifting motion to bring the tubers to the surface. It is often helpful to use one hand to steady the "handle" (the six-inch stem you left behind) while the other hand operates the shovel. However, never pull hard on the stem itself, as this can snap the necks of the tubers.
3. Clear Excess Dirt
Shake the clump gently to remove large clods of soil. If the soil is dry, it may fall away easily. If it is damp, you can let the clump sit in the sun for an hour or two to dry out. Use your fingers or a soft brush to remove the remaining dirt from between the tubers.
4. Label Immediately
As soon as the clump is out of the ground, label it. It is very easy to forget which variety is which once the flowers are gone. You can write the name directly on a large tuber with a permanent marker or tie a waterproof tag to the stem.
What to do next:
- Check each clump for signs of damage or soft spots.
- Trim away any long, thin "hair roots" with clean snips.
- Ensure the variety name is clearly marked before moving to the next plant.
Cleaning and Curing Your Tubers
After digging, you need to decide whether to wash your tubers. Some gardeners prefer to wash them thoroughly with a garden hose to see the "eyes" more clearly, while others prefer to leave a little soil on as a natural protective layer. Both methods work well. If you do wash them, be sure to let them dry completely in a shaded, well-ventilated area for 24 to 48 hours.
If you dig your dahlias early when the weather is still warm, avoid leaving the tubers in direct, hot sunlight for more than an hour or two. Excessive heat can cause them to shrivel. A garage, shed, or covered porch is an ideal place for them to air dry. The goal is to have the surface of the tuber feel dry to the touch and any remaining soil feel like dust.
To Divide or Not to Divide?
One of the benefits of digging early is that the tubers are still relatively soft. This makes them much easier to divide than they will be in the spring after they have toughened up in storage. However, dividing in the fall requires you to be able to identify the "eyes" on the crown of the tuber.
If you can see small, pimple-like bumps near where the tuber meets the stem, you can safely cut those tubers away. Each division must have a piece of the crown and at least one eye to grow. If the eyes aren't visible yet, it is perfectly fine to store the entire clump as it is. Many of us at Longfield Gardens prefer to store the clumps whole and divide them in the spring when the eyes naturally begin to swell and sprout. This "wait and see" approach is often safer for beginners.
Winter Storage Essentials
Once your tubers are dry and labeled, they need a cozy place to spend the winter. The goal of storage is to keep the tubers dormant without letting them freeze or dry out completely.
The ideal storage temperature is between 40°F and 45°F. If the temperature stays too warm (above 50°F), the tubers may try to grow or begin to rot. If it drops below freezing, the water inside the tubers will expand and turn them into mush. Unheated basements, crawl spaces, or insulated garages are usually the best spots.
For a storage medium, we recommend using something that regulates moisture. Common choices include:
- Pine Shavings: These are inexpensive and provide excellent air circulation.
- Vermiculite: This mineral holds a bit of moisture and is very effective at preventing shriveling.
- Peat Moss: A classic choice, though it can be dusty to work with.
Layer your tubers in a cardboard box or plastic bin so they are not touching each other. This prevents a single spoiled tuber from affecting the entire batch. If using plastic bins, leave the lid slightly ajar or drill a few small holes in the sides to allow for air exchange.
Monitoring Your Success
Since you have dug your tubers early, they will be in storage for a slightly longer period than those dug in late November. It is a good idea to check on them once a month. Open the boxes and look for any signs of trouble.
If the tubers look shriveled like a raisin, they are too dry. You can lightly mist the storage medium with water to add a touch of humidity. If you see any fuzzy mold or soft, dark spots, they are too damp. Remove any rotting tubers immediately and leave the box open for a day to allow excess moisture to escape.
Realistic Expectations for Overwintering
Storing dahlia tubers is a skill that improves with practice. Every home has a slightly different microclimate, and what works in a damp Michigan basement might not work in a dry Colorado garage. It is normal to lose a few tubers over the winter, even for experienced gardeners.
The health of your tubers in the spring depends largely on how they were treated during the summer. Plants that were well-watered and grown in healthy soil tend to produce the most robust tubers. By following these early digging steps, you are giving your dahlias the best possible chance to return for another spectacular season of color.
"The secret to successful dahlia storage isn't a magic trick; it's simply finding the right balance of temperature and moisture for your specific home environment."
Conclusion
Digging up your dahlia tubers early is a practical and effective way to manage your autumn garden. By focusing on plant maturity and providing a manual signal for dormancy through cutting back, you can harvest high-quality tubers on your own schedule. Whether you are avoiding the "black mush" of the first frost or just enjoying the last warm days of the season, early digging simplifies the process and keeps gardening a rewarding, stress-free activity.
We are here to help you grow the garden of your dreams with premium bulbs and expert advice. For the best results next year, remember to keep your stored tubers in a cool, dark place and check them occasionally for moisture.
Ready for next season?
- Mark your calendar to check your tubers in January and February.
- Consider trying a new storage medium like vermiculite if you’ve had trouble with shriveling in the past.
- Browse our selection of assorted dahlias to find new varieties to add to your collection this spring.
FAQ
Can I dig up my dahlias if they are still blooming?
Yes, you can dig them up even if they are still in full bloom. However, you should still cut the plants back and wait about a week before digging. This allows the plant to shift its energy from flower production to tuber maturation and helps the skin toughen up for storage.
How many days do dahlias need to grow before I can dig the tubers?
Dahlias generally need about 120 to 135 days of growth to produce mature tubers that will survive the winter. If you planted your dahlias in late spring, they should reach this stage by early to mid-October in most regions.
Will the tubers grow if I don't wait for a frost?
Yes, dahlia tubers do not require a frost to become "viable" for the next year. As long as the plant has reached maturity and you have allowed the tubers to cure in the ground for a few days after cutting the stalks, they will grow perfectly well the following spring.
What happens if I dig my dahlia tubers too early in the summer?
If you dig tubers in the heat of mid-summer, they will likely be too small and immature to store successfully. These young tubers have very thin skins and high water content, which causes them to shrivel rapidly once removed from the soil. It is best to wait until at least October for the most reliable results.
