How to Store Dahlia Tubers
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How to store dahlia tubers comes down to four jobs: lift the clumps at the right time, dry them without leaving them soggy, keep them in a cool and dark place that does not freeze, and check on them through the winter. The extension sources agree on the goal, which is to keep the tubers dormant and firm until spring. They disagree on the details, especially washing and the exact temperature. This guide shows where the figures differ instead of picking one number as the answer.
Quick answer
- Lift the clumps gently after a hard frost has killed the stalks, and dig well away from the stems.
- Let the clumps dry before storage. The sources differ on washing, so choose one method and apply it consistently.
- Store the tubers somewhere cool, dark and frost-free, and check them through winter for rot and moisture.
- Avoid sealed plastic and refrigerators. Oregon State warns that moisture builds up in a sealed container, and Ask Extension says most experts advise against refrigerating tubers.
Start preparing in late summer
Storage starts before the digging does. Oregon State advises withholding fertilizer starting in September, which lets the tubers harden off. The guide says the hardened outer layer helps tubers avoid damage during digging, and that hardened tubers store much better over the winter. Its feeding advice matches the same concern: too much nitrogen promotes weak stems, small or no blooms, and tubers that rot or shrivel in storage.
Handling matters too. Oregon State warns against sharp tools when cleaning the clumps, because they damage the skin of the tubers, which affects how well the tubers store.
Lift the clumps at the right time
Oregon State says to prepare for division after a hard frost has killed the stalks of the plants. It describes removing all of the foliage first, with pruners or by hand. Washington State tells gardeners to cut the stalk down to about 6 inches and then lift the tuber carefully by digging around the entire plant. Oregon State adds a distance: dig about 18 inches away from the stalk to avoid damaging the tubers. Utah State says to lift the clumps gently in the fall.
Timing matters because of frost. Oregon State says dahlias can handle rain but will rot if the ground freezes, so a clump left in cold, wet soil is at risk. North Carolina State says that to keep dahlias as perennials in zones below 7, the tubers should be dug up in fall. In zones 7 to 10, the same entry says to mulch over the bed for winter instead. Ask Extension, answering a question about storage, makes the same point about freezing: freezing temperatures ruin tubers.
For a tool to lift a heavy clump from wet ground, see our garden fork comparison.
Clean and dry the clumps
This is where the sources disagree most. The table sets out what each one says.
| Source | What it says about cleaning | What it says about drying |
|---|---|---|
| Oregon State University | In a fall division, wash the clump carefully. In the spring method, remove excess soil in the garden and do not use water before storing. | Air dry the clump for a few days. Do not store clumps that are soaking wet and muddy. |
| Washington State University | Hose the dirt off the clump | Let the clump dry before dividing and storing |
| North Carolina State University | Do not wash | Dry carefully |
| Ask Extension, expert answer | Rinse to remove clumps of soil that can hold moisture and microorganisms | Cure out of direct sun in a dry, well-ventilated place at 60 to 70 degrees Fahrenheit for 1 to 3 days |
Two sources say to wash or hose the clump, one says not to wash, and the expert answer says to rinse and then cure. Each one is trying to get the soil and moisture off the tuber before it goes into storage. Whichever method you pick, the sources agree on the core point: the clump must be dry before it is stored, and a soaking wet, muddy clump should not go into a container.
Divide the tubers and keep the eyes
Each stored piece needs a crown with an eye. Oregon State describes the eyes as swollen bumps next to the stalk and crown in fall, and it says not every tuber has a viable eye. It also tells gardeners to remove and discard all broken-necked tubers first, and to trim excess feeder roots or tails from the tubers that remain. Utah State says a piece of the crown with an eye should stay connected to each root, and that roots without an eye will not grow and should be thrown away.
The timing of division is a choice. Oregon State says fall is the most common time to divide, because it gives an early count of how many tubers there are. Ask Extension notes that most commercial growers divide in fall, but that the critical eye is harder to find then. Many people cut big clumps into smaller clumps of whole tubers, and then divide those in spring once the eyes show. Oregon State adds that spring division makes the eyes easier to see, which can speed up the process.
When eyes are hard to see, Utah State suggests keeping the clumps moist in a warm place for a short time, so that sprouts form and show where the eyes are before you divide them. For labels that keep each clump’s variety name readable through the winter, see our plant labels comparison.
Choose a container and a medium
A storage container should let air move and keep moisture from building up. Oregon State says plastic bags or cardboard boxes work well. It says a plastic tote works too, provided its lid is not airtight, and it warns that moisture in a sealed plastic container can rot the tubers. Oregon State also says to cover the clumps with layered newspaper, and to add enough medium to cover the tubers.
Ask Extension lists Styrofoam, wood and cardboard containers as options. It notes that a wood or cardboard box lets moisture escape, so it advises lining the box with newspaper at least eight sheets thick on all sides and keeping the top closed. Its advice to keep a box closed and Oregon State’s warning against sealing a plastic bag are about different containers, and the sources do not compare the two directly.
The medium is the material around the tubers. North Carolina State names vermiculite or dry sand. Ask Extension says vermiculite, wood shavings or sand can all work, and that the choice comes down to preference, as long as the medium holds some moisture and prevents fungus and rot. Washington State says shavings or a similar medium keep the tubers separated. Oregon State warns that wood shavings can cause the tubers to shrivel, and that a shavings medium needs monitoring through winter and light misting if the tubers begin to shrivel.
Pick the storage spot and temperature
The sources give different temperature figures, so the table lists each one with the condition it sets.
| Source | Temperature or condition | Note in the source |
|---|---|---|
| Oregon State University | About 34 to 40 degrees Fahrenheit, in a dark place that does not freeze | If the clump freezes, it will rot |
| Washington State University | A cool storage area that is not subject to freezing | No figure given |
| North Carolina State University | 35 to 45 degrees Fahrenheit, in vermiculite or dry sand | For zones below 7, where tubers are kept as perennials |
| Utah State University | A cool, dry place, such as an attic where the temperature does not drop to freezing | No figure beyond freezing |
| Ask Extension, expert answer | 40 to 50 degrees Fahrenheit as the ideal dormancy figure | Higher temperatures encourage fungus and early sprouting, and a heated home can be hard to keep this cool |
The figures differ by about 5 degrees at each end, but the core rule holds across all five sources: keep the tubers cool enough to stay dormant and never let them freeze. The expert answer adds that the air should move, and that the place should be cool and dark. Oregon State pairs its temperature with a dark location, so light exposure matters as well as temperature.
Check the tubers through the winter
Storage is not a set-and-forget job. Oregon State advises checking the storage bags through the winter for excess moisture, which shows up as condensation on the bag. If there is condensation, the guide says to check for rotting tubers, remove any rotted ones, and let the bag air dry before returning it to storage. Washington State says to check a couple of times through the winter and discard any tubers that are rotting. It adds that a tuber that seems shriveled can be sprayed with a small amount of water.
Bring the tubers out in spring
Oregon State says that as spring approaches, in March or April, the overwintered clumps should be moved to a location of about 40 to 50 degrees Fahrenheit. That warmth helps trigger visible eyes, or sprouts, if they have not already formed. Once the eyes show, a clump can be divided. The spring steps include an air-drying period, and Oregon State says not to store clumps that are soaking wet.
Consider leaving tubers in the ground
Some gardeners leave dormant tubers in the ground instead of storing them. Oregon State describes overwintering this way, and says it saves storage space. Whether it works depends on where you live and how cold the winter gets. The guide says the bed must drain well and have no standing water, and it says to apply at least 4 inches of organic mulch or leaves. North Carolina State says that in zones 7 to 10 the bed can be mulched over in winter. Ask Extension, answering a planting question, suggests a deeper planting of about 3 to 5 inches for a gardener who wants to try overwintering in the ground, with mulch added before winter.
Common mistakes to avoid
- Storing muddy or soaking wet clumps. Oregon State says not to store them in that state.
- Sealing a plastic container airtight. Oregon State warns that moisture builds up and can rot the tubers.
- Letting the tubers freeze. Oregon State and Ask Extension both warn about freezing, and Washington State says storage should not be subject to freezing.
- Storing them too warm. Ask Extension links higher temperatures to fungus and early sprouting.
- Feeding with too much nitrogen. Oregon State links it to tubers that rot or shrivel in storage.
- Refrigerating wrapped tubers. Ask Extension says most experts advise against it.
- Skipping the winter check. Oregon State and Washington State both call for periodic checks.
What we could not verify
What the sources do not say
The sources do not agree on washing, and they give three different temperature ranges. None of the pages opened for this guide gives a humidity figure for stored tubers, so the only moisture guidance is to keep the medium lightly moist and avoid soggy or wet conditions. None gives a storage length for a stored tuber, so this guide does not set one. The Oregon State and Washington State pages are written for Pacific Northwest growers, and the North Carolina State entry describes zones by number, so the match to your own climate is left to you. The pages opened also do not give a container size or a count of tubers per box.
How we chose
This guide relied on university and cooperative extension pages, a state university handout, and one question service staffed by extension experts. Each page had to load on 2026-10-23 and contain storage advice for dahlia tubers. The sources were chosen for their storage sections, not ranked against one another. Pages that returned a 403 status or did not respond were left out, including a Clemson HGIC seed-saving page that returned 403. Retail listings and blogs were not used. Where two sources disagree, both figures appear in the text.
Frequently asked questions
Should dahlia tubers be washed before storage?
The sources do not agree. Washington State says to hose the dirt off and let the clump dry. Oregon State says to wash gently in a fall division, but not to use water in the spring method. North Carolina State says not to wash. Whichever you choose, let the clump dry before it goes into storage.
What temperature suits stored dahlia tubers?
Oregon State gives about 34 to 40 degrees Fahrenheit in a dark place that does not freeze. North Carolina State gives 35 to 45 degrees Fahrenheit in vermiculite or dry sand. Ask Extension calls 40 to 50 degrees Fahrenheit the ideal dormancy figure. Oregon State, Washington State and Utah State all say the tubers should stay above freezing.
Can dahlia tubers be kept in a refrigerator?
Ask Extension describes wrapping tubers in plastic and refrigerating them as a new approach, and says most experts recommend against it because the tubers become more susceptible to rot. If it is the only choice, the answer says it may be tried, but it may not work.
Are fall or spring divisions better for storage?
Oregon State says fall is the most common time to divide, because it gives an early count of the tubers. Ask Extension adds that fall division makes the tubers easier to store and quicker to plant in spring, though the eyes are harder to find then. The same answer says either season can work.
What should a gardener check during winter?
Look for condensation on the bags, and for tubers that have started to rot. Washington State says to discard rotting tubers and to check a couple of times through the winter. Oregon State says to mist shriveled tubers lightly when they are kept in wood shavings, and Washington State says a small amount of water can be sprayed on tubers that seem shriveled.
Sources
- Oregon State University Extension Service, Dahlias in Oregon (FS 95, PDF): https://extension.oregonstate.edu/sites/extd8/files/catalog/auto/FS95.pdf (opened 2026-10-23)
- Washington State University, Growing Dahlias (handout, PDF): https://s3.wp.wsu.edu/uploads/sites/2056/2023/10/Growing-Dahlias-handout-2023.pdf (opened 2026-10-23)
- Utah State University Extension, Dahlias (PDF): https://extension.usu.edu/yardandgarden/files/Dahlias.pdf (opened 2026-10-23)
- North Carolina State University Extension, Plant Toolbox: Dahlia: https://plants.ces.ncsu.edu/plants/dahlia/common-name/dahlia/ (opened 2026-10-23)
- Ask Extension, How to store dahlias? (question 888581): https://ask.extension.org/kb/faq.php?id=888581 (opened 2026-10-23)
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