Introduction
There is a special kind of satisfaction that comes at the end of a dahlia season. After months of enjoying dinnerplate-sized blooms and vibrant colors that light up the garden, the first frost signals a transition. While the top of the plant may fade, the real treasure lies beneath the soil. Lifting and saving your dahlia tubers is a rewarding way to build your collection and ensure your favorite varieties return year after year.
One of the most common questions we receive at Longfield Gardens is whether you should wash your dahlia tubers before tucking them away for the winter. It is a topic that sparks plenty of friendly debate among gardeners.
This guide will help you decide which approach is right for your garden. We will cover the benefits of both methods, how to properly cure your tubers, and the simple steps you can take to keep them healthy until spring. Whether you are a first-time dahlia grower or a seasoned pro, the goal is to make winter storage a simple and successful part of your gardening routine.
The Big Question: To Wash or Not to Wash?
The short answer is that both methods can work beautifully. The decision usually depends on your personal preference, your local climate, and how you plan to store the tubers. There is no single "right" way, but there are specific reasons why a gardener might choose one over the other.
At its core, the choice to wash is about visibility and cleanliness. The choice not to wash is about protection and simplicity. Understanding the "why" behind each method allows you to choose the path that fits your schedule and storage environment.
Why You Might Choose to Wash Tubers
Many gardeners prefer to wash their dahlia tubers because it provides a clear view of what they are working with. When you spray away the garden soil, you get an unobstructed look at the tuber's skin and the "neck" of the plant.
Washing makes it much easier to identify the "eyes." These are the small growth points, similar to the eyes on a potato, that will produce next year’s stems. If you plan to divide your tubers in the fall rather than the spring, washing is almost essential. It allows you to see exactly where to make your cuts without damaging the most important parts of the clump.
Cleaning also helps you spot potential issues early. You can easily see signs of insect damage or soft spots that might lead to rot during the winter. By removing the soil, you are also removing any soil-borne pests or fungi that might want to hitch a ride into your storage area.
Why You Might Choose Not to Wash Tubers
On the other hand, many successful growers prefer to leave the dirt right where it is. If you have light, sandy soil, it often falls away naturally as the tubers dry, making a heavy wash unnecessary.
Leaving a bit of soil on the tubers can act as a natural protective buffer. It helps maintain a tiny bit of moisture around the skin, which can prevent the tubers from shriveling in very dry storage conditions. This is often compared to how potatoes are stored; they seem to stay "dormant" and happy when left in their natural state.
Skipping the wash is also a great time-saver. If you have dozens of dahlia plants to dig up before a hard freeze, skipping the hose-down allows you to get the tubers into a protected area much faster. For many, the "no-wash" method is the simplest way to ensure a successful dormant period with minimal fuss.
Key Takeaway: Wash your tubers if you plan to divide them immediately or if your soil is heavy clay. Leave them unwashed if you have sandy soil or if you want to save time and provide a natural moisture buffer.
Preparing to Lift Your Dahlias
Before you decide on washing, you need to get the tubers out of the ground safely. Timing is everything when it comes to lifting dahlias. In most regions, the best time to start is after the first frost has turned the foliage black or brown. For more guidance, see this guide to digging up dahlia tubers.
This frost sends a signal to the plant to shift its energy into the tubers for winter storage. If you live in a climate where frost comes very late, you can simply cut the plants back in mid-to-late autumn to initiate this dormancy.
Cutting Back the Stalks
Start by cutting the stalks down to about 4 to 6 inches above the ground. Use a clean pair of loppers or a garden saw. Leaving this short "handle" of the stalk makes it much easier to handle the heavy clumps without putting pressure on the fragile necks of the tubers.
Once the stalks are cut, some gardeners like to leave the tubers in the ground for a few days to a week. This is sometimes called "curing in the ground," and it can help the eyes become more prominent. However, if your soil is very wet or a deep freeze is coming, it is better to lift them sooner.
Digging with Care
When you are ready to dig, use a garden fork or a sturdy shovel. Start digging about 12 inches away from the base of the stalk. You want to avoid piercing the tubers, as any wounds can become entry points for rot.
Gently pry upward from all sides of the clump until it feels loose. Then, lift the entire mass of tubers from the soil using the stalk handle. Shake off the heaviest chunks of soil by hand before moving to your cleaning or drying station.
How to Wash Dahlia Tubers Correctly
If you have decided that washing is the best path for you, doing it correctly is vital for preventing rot. The most important rule of washing is that the tubers must be completely dry before they go into final storage.
The Gentle Rinse
Use a garden hose with a gentle spray nozzle. Avoid using a high-pressure power washer, as the skin of a freshly dug tuber is quite thin and easily bruised. Focus the water on the center of the clump where soil tends to get trapped.
As you wash, rotate the clump to reach all the nooks and crannies. You don't need the tubers to be "kitchen clean," but you want the majority of the soil gone so you can see the color of the skin and the location of the eyes.
Trimming the "Mother" Tuber and Hair Roots
Once the clump is clean, you might notice a large, older tuber in the center that looks a bit different from the others. This is often the original "mother" tuber you planted in the spring. Sometimes these can begin to decay at the end of the season. If it looks shriveled or soft, it is a good idea to trim it away now.
You can also trim off the long, thin "hair roots" that dangle from the bottom of the fleshy tubers. These don't serve a purpose during dormancy and can sometimes mold if they stay too wet.
Drying After the Wash
This is the most critical step. If you put wet tubers into a box, they will likely rot within weeks. Place your washed tubers in a frost-free, shaded area with excellent air circulation. A garage or a covered porch works well.
Lay them out on a screen, a pallet, or a layer of cardboard. Upside down is often best, as it allows any water trapped in the hollow stalks to drain out. Let them dry for 24 to 48 hours. The skin should feel dry and slightly tough to the touch before you proceed.
The "No-Wash" Method: Step-by-Step
If you prefer the simpler route, the process is even faster. This method is excellent for gardeners who find that their tubers stay plump and healthy without extra intervention.
Air Drying the Soil
After lifting the clumps, move them to a dry, protected spot. Instead of washing them, let them sit for a day or two so the soil can dry out. As the moisture leaves the soil, it will naturally shrink and pull away from the tubers.
Brushing Away the Excess
Once the soil is dry, you can use your hands or a soft brush to knock away the large clumps. You aren't looking for a spotless tuber; you just want to remove the bulk of the earth so the crates or boxes stay relatively clean.
The thin layer of dust or soil that remains acts as a protective skin. Many gardeners find that this helps the tubers regulate their own moisture levels throughout the long winter months.
Curing Your Tubers for Success
Regardless of whether you washed your tubers or left them "dirty," they all need a period of curing. Curing is simply a fancy word for letting the tubers rest so their skins can toughen up for storage.
Think of it like curing an onion or a potato. A freshly dug dahlia tuber is very tender. If you pack it away immediately, the skin can easily tear. A cured tuber has a slightly "cork-like" feel to the skin, which makes it much more resistant to disease and desiccation (drying out).
- Duration: Aim for 2 to 3 days of curing.
- Environment: Keep them out of direct sunlight and away from freezing temperatures.
- Airflow: Use a fan if the air is very humid to ensure they stay dry.
What to do next:
- Select a dry, shaded workspace for your tubers.
- Lay them out in a single layer to ensure airflow.
- Check the hollow stalks for any standing water and drain them.
- Wait until the skins feel firm before packing.
Choosing Your Storage Medium
Once your tubers are clean (or brushed) and cured, it is time to pack them away. At Longfield Gardens, we have found that the storage medium you choose is just as important as whether you washed the tubers. For additional storage guidance, see what to store dahlia tubers in during winter.
The goal of a storage medium is to maintain a balance: it needs to keep the tubers from drying out completely while also absorbing any excess moisture that could cause mold.
Peat Moss
Peat moss is a classic choice. It is lightweight and has natural anti-fungal properties. If you use peat moss, make sure it is only very slightly damp—not wet. Most gardeners find that peat moss straight out of the bag has just the right amount of residual moisture.
Vermiculite or Perlite
These are excellent options for gardeners who live in humid climates. They are very good at absorbing excess moisture and providing air pockets around the tubers. They are also very clean to work with.
Wood Shavings
Pine shavings (the kind used for animal bedding) are popular because they are inexpensive and provide great insulation. However, be cautious with very fine sawdust, as it can sometimes draw too much moisture out of the tubers and cause them to shrivel.
Newspaper or Cardboard
For a low-cost option, wrapping individual tubers in several layers of newspaper can work well. The paper acts as a buffer and keeps the tubers from touching one another, which prevents a single bad tuber from "infecting" the rest of the batch.
The Perfect Storage Environment
Your dahlias are now packed and ready. But where should they go? The environment where you keep your storage containers will determine if your tubers stay dormant or start to rot or sprout.
Temperature is Key
The "Goldilocks zone" for dahlia storage is between 40°F and 50°F. If the temperature stays in this range, the tubers will remain dormant.
- Too Cold: If the temperature drops below freezing (32°F), the tubers will turn to mush and die.
- Too Warm: If the temperature stays above 55°F, the tubers may think it is spring and start to grow spindly sprouts, which depletes their energy.
For more ideas, read where to store dahlia tubers over winter.
Humidity and Airflow
Dahlias prefer a relatively high humidity environment (around 75% to 85%), which keeps them plump. However, high humidity without airflow is a recipe for mold. If you are using plastic bins for storage, it is a good idea to leave the lids slightly ajar or drill a few small holes in the sides to allow the tubers to "breathe."
Winter Check-Ups: The Secret to Success
One of the most important parts of storing dahlias is not forgetting about them! We recommend checking your tubers once a month during the winter. This simple habit can save your entire collection.
What to Look For
Open your boxes or crates and take a quick peek. You are looking for two things:
- Signs of Rot: If you see a tuber that is soft, mushy, or covered in fuzzy mold, remove it immediately. You can often cut away a small rotten spot and save the rest of the tuber, but if it is completely soft, throw it away.
- Signs of Shriveling: If the tubers look like a wrinkled raisin, they are getting too dry. You can lightly mist the storage medium with a spray bottle to add a tiny bit of moisture back into the environment.
Adjusting as You Go
Gardening is all about observing and adjusting. If you find that your basement is too dry, you might need to close the lids on your containers more tightly. If you see condensation on the inside of your bins, it is time to open them up and let them air out for a day.
Key Takeaway: A quick monthly check-up allows you to catch small issues before they become big problems. Most dahlia losses happen because of a "set it and forget it" approach.
When to Divide Your Tubers
The question of washing often goes hand-in-hand with the question of when to divide. Dividing is the process of cutting a large clump of tubers into individual pieces, each with its own eye. For more help, see this step-by-step guide to dividing dahlia tubers.
Fall Division
If you wash your tubers, fall is a great time to divide. The tubers are still somewhat flexible, making them easier to cut. Once they are divided and cleaned, they take up much less space in storage. You can pack hundreds of individual tubers into the same space that only a few large clumps would occupy.
Spring Division
If you prefer the "no-wash" method and leave the clumps whole, you will wait until spring to divide. Many gardeners find this easier because the eyes are much more visible in the spring as they begin to swell and turn pink or green. The tubers are tougher in the spring, so you might need a sharper knife, but the "target" (the eye) is much easier to hit.
Summary of the Best Practices
Saving dahlias doesn't have to be a stressful chore. Whether you choose to wash your tubers or leave them with a bit of garden soil, success comes down to the basics of care and observation.
- Lifting: Dig gently after the first frost, leaving a short handle of the stalk.
- Cleaning: Wash if you want to see the eyes and divide now; leave them dirty if you want a natural moisture buffer and a faster process.
- Curing: Always let the skins dry and toughen for 2 to 3 days before packing.
- Packing: Use a breathable medium like peat moss or vermiculite.
- Storing: Keep them in a cool (40–50°F), dark place.
- Monitoring: Check once a month for rot or shriveling and adjust accordingly.
Conclusion
Storing dahlia tubers is one of the most rewarding parts of the gardening cycle. It turns a single season of beauty into a lifetime of blooms. Whether you decide that washing fits your style or you prefer the "earthy" approach of storing them with soil, the most important thing is to give them a cool, dry, and protected home for the winter.
At Longfield Gardens, we love seeing our customers grow their collections and share their favorite varieties with friends and neighbors. If you are ready to add more dinnerplate varieties, the Thomas Edison and Lilac Time dahlia collection is one option to explore. By taking these simple steps to protect your tubers now, you are setting the stage for a spectacular show next summer.
Final Thought: Your dahlias are tougher than they look. As long as they stay cool and dry, they will be ready to burst back into life the moment the spring sun warms the soil.
FAQ
Should I use bleach when washing my dahlia tubers?
While some growers use a very diluted bleach solution to kill surface bacteria, it is generally not necessary for the home gardener. As long as you dry your tubers thoroughly and store them in a clean medium like peat moss, they will stay healthy on their own. Simple, clean water is usually all you need.
Can I store my dahlia tubers in a refrigerator?
A refrigerator can work if you don't have a cool basement or garage, but it is not ideal. Most refrigerators are kept at about 35–38°F, which is a bit too cold, and the air inside is very dry. If you must use a fridge, place the tubers in a sealed container with a slightly damp medium to prevent them from drying out. For more winter storage guidance, read how long dahlia tubers can be stored.
What if I accidentally cut a tuber while digging it up?
Don't worry—this happens to everyone! If you nick a tuber, simply let it air dry so the wound can "callous" over. As long as the neck and the eye of the tuber are intact, it will usually grow just fine. If a tuber is severely mangled, it is best to trim it off to prevent rot from spreading to the rest of the clump.
Do I have to wash the tubers to see the eyes?
Washing certainly makes the eyes easier to spot, but it isn't strictly necessary. If you store your tubers as whole clumps with the soil on, the eyes will become much more prominent in the spring as they naturally begin to wake up. For many beginners, waiting until spring to find the eyes is much easier than trying to spot them on a freshly dug fall tuber.
