3 Simple Ways to Cut Dahlia Tubers (2024)

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Co-authored bySophia Latorre

Last Updated: September 12, 2020References

1. 1

   Cut back the stalks 3-4 days before digging up your dahlias. Dahlia tubers can survive the first frost of the season, but won't survive once the ground starts to freeze. The first frost will kill off the parts of the dahlia plant that are above the soil. Once this happens, cut the stalks of your dahlias back so that they’re 3–6 inches (7.6–15.2cm) tall.^[1]

   • Leave your dahlia tubers in the ground as long as possible to give them a better chance of surviving the winter in storage.
   • When cutting back the stalks, pull out and throw away any dahlia plants that didn’t bloom or grow well.
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   Cover your cut dahlias with foil to prevent water rot. Once you've cut your dahlia stalks back, cover each plant with a sheet of aluminum foil. The foil will prevent water from getting inside the stalks or stems, which could cause them to rot.^[2]

   • Leaving the dahlias to sit in the soil for 3-4 days between cutting back the stalks and digging up the plants will help the ‘eyes’ of the plant, or the parts where the tubers grow from, become more obvious. When you divide the tubers, you'll have to make sure each section has an eye, or they won't regrow.
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   Dig a circle around the dahlia 10–12 inches (25–30cm) from the stalk. Use a shovel or pitchfork to dig a wide circle around your dahlias that’s 4–6 inches (10–15cm) deep. Be very careful not to damage or pierce the tubers, which are underneath the stalks.^[3]

   • The roots of your dahlias may have spread past the 10–12in (25–30cm) radius of the circle you’re digging. It’s okay to cut the roots with your shovel or pitchfork.
4. See Also

   How to overwinter dahlias – an expert guideHow to grow dahlias / RHS GardeningDahlia Care — Dahlia | SummerDreamsFarmOur Complete Guide To Planting Dahlia Tubers

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   Loosen the soil around the dahlia tubers and lift it out of the soil. Use a shovel or pitchfork, or even your hands, to gently loosen the soil inside the circle. Then, use the shovel or pitchfork to scoop under the entire dahlia plant at a depth of 4–6 inches (10–15cm). Carefully lift the entire dahlia plant—tubers, roots, and stalk—up and out of the soil.^[4]

   • Be very careful not to puncture or damage the tubers when you scoop under the entire plant.

   Warning: Do not lift the dahlia plant out of the soil by pulling it from above. The stalks are very fragile and may break if you attempt to pull on them.

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   Remove all the soil from around the roots and tubers. Shake off as much loose soil as you can while holding the plant on your shovel or pitchfork. Place the dahlia plant on the ground and use your hands to remove even more loose soil, then use a garden hose to wash off the rest.^[5]

   • Be careful not to damage the tubers or the stalks the tubers are attached to.
   • Since you'll remove the roots later, don’t worry if you break them off the plant.

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   Cut away feeder roots and the bottoms of the tubers. Use garden shears to cut off all the roots sticking out of the dahlia plant. Also, use the shears to cut the tip off the bottom of each tuber. Cut back the stalk of the plant until only 2–3 inches (5.1–7.6cm) is left.^[6]

   • Neither the roots nor the tuber tips are required to regrow the dahlia in the spring.
   • If you can obviously see the ‘eyes’ of the tubers, which look like little pink bumps, you can cut back the stalk and crown even further, so long as you don't remove the eyes.
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   Separate each individual tuber from the clump. Use your garden shears or a sharp knife to cut the dahlia crown and divide the clump into individual tubers. Make sure that each and every tuber you separate has one eye attached to the top. Without an eye, the tuber will not be able to regrow in the spring.^[7]

   • The crown is the part of the plant that connects the tubers to the stalk of the plant.
   • Some gardeners separate their tubers in the fall after they’ve dug up all their dahlias. Others prefer to wait and divide the tubers in the spring, just before they’re replanted. The tubers will be easier to cut in the fall, but the eyes will be easier to find in the spring.
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   Trim the excess stalk and crown around each tuber’s eye. Use your garden shears to cut back as much of the remaining stalk and crown as you can. If you’re unsure where the eye is, only cut back the stalk and wait until spring to trim the crown.^[8]

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   Sterilize the tubers in a solution of bleach and water. Mix 10 parts water and 1 part bleach in a bucket or sink. Place each tuber in the bleach solution for 5-15 minutes to kill any fungi or viruses that may be present.^[9] Alternatively, rather than sterilizing the tubers themselves, you can use the same bleach solution to sterilize your garden shears or knife before and after using them on each specific plant.^[10]

   • Dahlias are known to have certain viruses that can destroy and kill them, so sterilization is an important step.
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   Allow the tubers to dry for 2-3 days before storing them. Put your newly sterilized dahlia tubers in a cool and dry place for a few days. Lay the tubers on several sheets of newspaper to dry. Don’t pack your tubers for winter storage while they’re still damp or they may rot.^[11]

   • Do not place your tubers on concrete to dry. The concrete will suck all the moisture out of the tubers, which may cause them to shrivel up and die.^[12]
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   Mark the dahlia tubers if you have different colors or varieties. It's best to work on one clump at a time so you can keep track of what kind of dahlias they are. Use an indelible pencil or marker to write the name or color on each tuber.^[13]

   • You can find indelible pencils and markers at craft stores and online.
   • Indelible pencils and markers are toxic since the lead contains dye, so don't put them in your mouth and be sure to keep them away from pets and children.

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   Select a loose and airy material to store the tubers in. Choose a material that’s loose and will allow air circulation, but can also hold moisture. Peat moss, vermiculite, moist sand, wood chips or shavings, shredded newspaper, dry compost, or sawdust are all good choices. Use whatever material you prefer based on cost and availability.^[14]

   • Estimate that you’ll need about 3 by 3 by 3 inches (7.6 ×7.6 ×7.6cm) of material per tuber.
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   Choose a storage container that will retain moisture. The container also needs to be sealable. You could use plastic freezer bags, multi-layered plastic grocery bags, plastic tubs or pots, Styrofoam containers, wood boxes, or cardboard boxes. Select containers based on what you have available and how many tubers you need to store.^[15]

   • Err on the side of caution and use a container that’s bigger than you need, rather than trying to stuff your tubers into a container that may be too small.
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   Pack your tubers inside the storage material and containers. Put a layer of packing material that’s 1–3in (2.5–7.6cm) deep in the container. Then, place the tubers on top of the material, making sure to leave space between them. Then add another 1–3in (2.5–7.6cm) deep layer of packing material. Continue layering the material and tubers until the container is full or you’ve packed away all your tubers. Seal the container when you're done.^[16]

   • If you use a wood or cardboard box, line the box with 8-10 pieces of newspaper before packing the tubers inside.
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   Store the tubers in a cool, dry, and dark location. Put the packed storage containers somewhere that is frost-free, dry, well-ventilated, and stays between 35–50°F (2–10°C). Your basem*nt, a root cellar, or a heated garage are good choices. However, avoid locations that could freeze in the winter, such as outdoor sheds or unheated garages.^[17]

   • While temperatures between 35–50°F (2–10°C) are okay, temperatures between 40–45°F (4–7°C) are ideal.
   • Make sure to put your tuber storage containers where you can access them throughout the winter.
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   Check on your tubers once a month over the winter. Inspect each container of tubers and check for rot. If you find any tubers that have started to rot, remove them and throw them out.^[18]

   • Depending on the temperature where the tubers are stored, you may notice some of them starting to sprout in the winter.

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