How to Overwinter and Store Dahlias

If you grow the magnificent dahlia flowers, you need to learn to store them overwinter.

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by Austin Graf
PHOTO: Danita Delimont/stock.adobe.com

Dahlias are perhaps one of the most popular cut flowers in the garden for many small cut-flower farmers and gardeners alike, and knowing how to overwinter and store dahlias is something you should know. Dahlias are stunning, giant blooms that put on a beautiful display from mid-summer to late into the fall, and they come in a range of colors, shapes and sizes.

Why Grow Dahlias?

Dahlias have quickly grown to be a staple “crop” in the cut-flower and garden industry for a few key reasons. The first of which is simply that their delicate petal structure means that they don’t ship very well, leaving an opportunity for small farmers to supply dahlias as cut flowers to local florists and floral designers.

If that alone wasn’t enough, dahlias have a unique ability to easily replicate, via tubers. Each plant creates large fingerlike tubers that can be split, divided and used to create clones of the mother plant. This allows gardens and cut flower farmers alike to purchase just a few dahlias and rapidly increase their stock year after year. Meaning you can keep the same dahlia root stock every single year with proper care, but how do you overwinter and store dahlias’ tubers?

Should I Dig Up Dahlias?

One of the biggest questions folks ask is “do I have to dig up my dahlias?” Well, the answer is yes and no. In gardening zones 7 and colder, dahlias should be dug up every fall to protect them from potentially freezing and rotting in the field over winter.

In warmer zones, they can be left over winter. With that said, many gardens and growers in zone 7 and 6, have found success with deep mulching methods or winter row covers to help insulate the tender tubers, and successfully overwinter outside.

One of the biggest dangers of overwintering dahlias in the ground is their chance of rotting. Ensure the soil is free draining and free of standing water to give them the best chance.

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Digging and Storing Dahlias Tubers

How to example
Наталья Дорожкина/stock.adobe.com

If you’re in a colder zone, you’ll need to dig your dahlia tubers in late fall, and that means you will need to store them as well.

To dig and store dahlia tubers:

Cut back the dahlia foliage leaving only a few inches of stem. Use a shovel or pitchfork to carefully loosen the soil around the dahlia avoiding cutting any tubers by accident. Shake off the excess dirt and soil.

Once dug, many growers have differing opinions. Many believe you should rinse your dahlias of all additional soil prior to storage, while other growers believe that leaving a thin layer of soil is beneficial. Regardless, you should trim away any rotten bits, to ensure the tubers don’t rot in storage.

The biggest key to successful tuber storage is ensuring your tubers stay in a cool, dark and dry space. Use vermiculite, wood shavings or peat moss. Store in milk crates, mesh bags, bulb crates, basically anything that allows for ample air circulation.

You can choose to divide tubers prior to storage, after storage, or not at all. I have had the best success storing tubers in full clumps dividing in spring a bit before planting, but feel free to experiment and see what works best in your home. Regardless, it’s critical to check in, and examine tubers for rot or mold throughout winter to avoid spoiling all your tubers.

And just like that, you’ve overwintered your dahlia tubers like a pro, and you’re ready to get planting!