Digging up Dahlia Tubers for Storage
If you live anywhere but the warmest regions of the United States, it’s time to dig up and store those precious dahlia tubers.
When in bloom, dahlias provide some of the garden's biggest and most spectacular flowers in many different sizes, forms, and colors. This year, my dahlias were especially productive - I made dozens of arrangements for my home. However, native to Mexico, dahlias are not winter-hardy and tend to split in freezing temperatures or mold in soggy, wet soil. This week at my Bedford, New York farm, my gardeners dug up all the dahlia tubers, so they could be stored indoors for the cold season.
Here is our step-by-step process. Enjoy these photos.
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- Wait until the foliage has turned yellow and brown before digging up the tubers. This is important so that the plant can gather energy for the following year. It will store starches in the tuber which will fuel initial sprouting in summer. The best time is a couple weeks after the first frost when they’re well into dormancy yet haven’t been harmed by the cold.
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- First, Ryan cuts all the stems down leaving about five to six inches of the main stem. These stems will be used to hold the tubers as they are lifted from the soil.
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- Dahlia stems are hollow making them quickly susceptible to rot. This is also why dahlias often have to be staked to help support their very large flowers.
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- Phurba digs up the dahlia tubers with a garden fork starting about a foot away from the center stem. He is very careful not to let the tool come into contact with any of the tuberous roots, which can be easily damaged.
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- I always say to “use the right tool for the right job.” My Martha Stewart garden forks from QVC are perfect for digging up our dahlia tubers. They come in sets of three, each with a fork, a shovel, and a spade for tilling, turning, and transplanting anything in the garden. https://qvc.co/377bklz
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- Phurba loosens the soil around the dahlia tubers by thrusting the fork into the ground and then slowly prying up the soil freeing the tubers.
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- With one hand on the stem, Phurba gently removes the entire mound from the ground.
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- Dahlia tubers consist of a stumpy stem with several swollen sections attached to it. Phurba pokes the clump gently to knock off most of the dirt.
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- Phurba and the others work in an assembly line fashion, so the task is done quickly and efficiently. While Phurba digs up the tubers, Gavin removes the cut plants from the area.
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- All of these dahlia tubers have been safely pulled and are ready to be rinsed.
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- Next, Phurba washes the dirt off the dahlia tubers by hosing them down. If you’ve already put the hoses away for the season, you can also swish the tuber around in a bucket of water. Be very gentle—even the slightest puncture can introduce pathogens, causing the dahlia bulbs to rot in storage.
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- Tuber productivity varies between varieties. Here, Ryan shows how small the tuber was when planted, and on the right, how much it has grown. Each clump pulled had anywhere from five to 20 tubers. Not all will have full eyes allowing them to grow a stem next spring, but we definitely harvested more than we planted.
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- Here is a clean clump of dahlia tubers with their roots intact.
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- To dry the dahlias, we use shallow plastic mesh trays like these that provide good air circulation. They’re available at Johnny’s Selected Seeds and can be ordered in multiples of five. https://bit.ly/355EPCu
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- Phurba carefully rinses all the dahlia tubers and leaves them in place until they are collected by the variety and put into trays with appropriate labels.
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- All the tubers will look similar, so it is crucial to keep them with their individual markers. These tubers are ‘Penhill Watermelon’ dahlias – a dinner plate variety with a giant fluffy mix of peach, lavender and the tiniest hint of yellow flowers.
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- Dahlia ‘Kelvin Floodlight’ is also a dinner plate variety – a butter-colored flower that grows up to 10-inches across.
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- This day was very rainy and wet, but these tubers are rinsed and waiting to be placed into trays.
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- Here are all the cut dahlias ready to be carted to the compost pile. Here it is easy to see what they look like after the first frost – all the foliage has darkened and died.
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- Before they are bagged and stored, the dahlia tubers must dry completely. Ryan places all the trays of dahlia tubers into our small hoop house where they can cure properly. The curing process involves high temperatures and high relative humidity to prepare the roots and tubers for long periods of storage and to heal the skins wounded during harvesting.
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- Now this garden bed is empty and ready for planting the next crop. I wonder what it will be. How did you prepare your dahlias for storage? Share your gardening comments with me in the section below.
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