This week I heard from a reader and one of my clients who appreciate the patio we made for him a few years ago. One of the new beds has been fitted with a number of new dahlias. He’s reached the point where he wants to overwinter the tuberous roots and wants to know the best way to conserve them for next year.
When I started in landscaping, I did an internship at Schoepfle Gardens in Birmingham, where I worked for a season. Joel, my supervisor, was tough but fair, and I remember at the end of the season all the dahlia tubers had come out of one of the beds in the garden. The soil that I removed the dahlias from was rich and black, which happens to be the favorite soil for dahlias.
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An interesting fact about dahlias is that they are part of the aster family because of flowering, I’m sure.
One of my other favorite dahlias keepsakes is the Dahlia Society displaying some of its beautiful flowers at Seacrest Arboretum. What I remember is walking in the garden and seeing all these beautiful flowers with single flowers and umbrellas covering the flowers on a hot summer afternoon.
You could see this huge yard with little umbrellas all over the yard covering the dahlia flowers. I thought it was a little strange. What I liked were the beautiful flowers; what a blessing to see the amazing flowers.
Caring for dahlias during the winter
What I remember about preserving dahlias is that after the first frost has blackened the foliage, which should happen soon, you cut the stems about six inches above the ground and discard the upper half. I also read that you have to get your dahlia out of the ground before the frost.
Frankly I can’t imagine you would have to leave the dahlia in the ground much longer than we have after the temperatures start to drop below 32 degrees. You really have to be really careful with those tuberous roots and gently dig the tubers out, taking care to remove most of the soil and broken roots. When you damage the tuberous roots, you have a great place to catch disease.
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Before you store your dahlia roots, you’re going to want to dry them out, so you need to leave the tuber upside down for about a week to wick away excess moisture. In the gardens of Schoepfle, there was a root cellar under Otto’s house. Seriously, I just don’t remember using dirt or anything to store them. The conditions inside the root cellar were ideal for the dahlias to do well.
One of the trials is that dahlia tubers can dry out if stored improperly. Therefore, you should think about storing them in, for example, peat soil that is not very moist or moist vermiculite to reduce the chances of contracting disease. You really shouldn’t completely cover the boxes while you are storing the dahlia. Crowns cannot be covered if the dahlia is to survive.
Temperature is important for dahlia storage
One of the keys to storing dahlias is that you should store dahlias within a temperature range of 30-50 degrees. As I said before, we are in ideal conditions to grow all kinds of fungi which can be harmful if the dahlia is damaged.
I wish you good luck in trying to preserve your dahlias. You may be able to enjoy these same plants for many years to come.
Hope you are taking a walk in your backyard this week and achieving the goals you set for yourself. You can email me at [email protected] Soon I will be relaunching the blog and linking it to the ohiohealthyfoodcooperative.org website. I will do my best to help you. Thank you all for your excellent questions.
Eric Lawson of Jeromesville is a seasoned landscaper and gardener enthusiast and founding member of the Ohio Chapter Board of Directors of the Association of Professional Landscape Designers.