‘Volunteer Gardener’ October in the Garden: Dahlia Season

It’s been so warm this year that dahlia production in the Nashville area has been difficult. Dahlias love warm days and cool nights, and there have precious few cool nights this season. However, with our recent change in the weather, we should start to see a few more luscious blooms from one of my favorite flowers.

Even as the dahlias finally begin to bloom in earnest, our enjoyment is bittersweet as we are also approaching our first hard frost of the year. In Nashville, the average first frost is October 28th. After that we have to decide whether to leave the dahlia tubers where they are, or take them up and store them over the winter.

I’ve gone back and forth through the years about whether to lift my dahlia tubers or leave them in place and I’ve done both with mixed results. Last winter was so wet that every tuber I left in the ground rotted – even some of the ones I planted out in the spring rotted! Now after losing hundreds of tubers, I think I’m in the “lifting” camp for good!

Why is it called “lifting”? Because you use a broad fork or garden fork and literally lift the soil from around the plant. A single dahlia tuber can multiply exponentially over a growing season, so if you use a shovel, you can easily slice through several tubers that could otherwise grow into entirely new plants in the spring.

After lifting, gently brush off any attached dirt with a stiff paint brush, then set the tubers out to cure for a few days. To store, place the tubers in boxes layered with peat moss or coir. (Some people also use perlite for this purpose.) Do not make the boxes airtight or mold may form and the tubers may rot. You will also want to check the tubers periodically over the winter. If you see mold forming, let the tubers air out and change the storage medium. If the tubers look shriveled, you might want to mist them gently with water.

I usually cut my tubers in the spring when I take them out of storage. Note: The eyes can continue to develop over the winter, so it’s important not to be in too big of a rush to separate them.

As you can see, dahlias are the divas of the cutting garden and require a lot of patience and care. But when they get that attention, they reward you with extravagant, long-lasting blooms, both in the garden as well as in the vase.

Happy gardening!

Laura Bigbee-Fott is a Davidson County Master Gardener. She owns Whites Creek Flower Farm and runs a floral event and wedding design business called Everything Blooms.