Storing Dahlia Tubers for Winter
Our dahlia digging and storing project continues at the farm.
Dahlias are frost-tender tuberous plants that can overwinter outdoors where the weather is mild. However, here in the Northeast, severe winter conditions will cause them to split and rot, so they must be pulled from the ground and stored away every fall. Several days ago, my gardeners uprooted all the dahlia tubers, rinsed them and set them inside the temperature and humidity-controlled greenhouse where they could cure. Now, they are ready for storing.
Enjoy these photos and tips.
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- Since dahlia plants only thrive as far north as USDA plant hardiness Zone 9, cold-climate gardeners must dig up and store the tubers each year.
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- Dahlia tubers – sometimes referred to as “bulbs” – are not true bulbs at all, as they differ in both appearance and growth function. Bulbs are round and consist of one swollen root. Tubers, come in a variety of shapes and form in a cluster. They also grow out of the “eyes.”
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- Here is a closer look at the hollow stem. It is completely dried through. If you don’t have a temperature and humidity-controlled greenhouse, these tubers can dry outside if there is no rain forecasted or in any room that does not get any direct sunlight. The drying process could take up to a couple of weeks.
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- Ryan inspects each dahlia tuber and trims away any parts that are rotten. He also checks the “mother” tuber or the original tuber that was planted, which is more likely to rot than the new ones.
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- Just to be sure, Ryan also writes the variety of the dahlia on one of the tubers, so there is absolutely no confusion later.
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- Next, Ryan trims the stem slightly, so it is just about two to three inches long.
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- Ryan coats any cut side with Douglas fir bark dust. This dust helps to heal the sliced area, so it doesn’t shrink or curl. The slightly acidic bark is also a natural fungicide and moisture buildup barrier that will help deter rot. Come spring, the dust can be left on it when planted to thwart decay before they sprout.
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- You can find fir bark dust in some specialty garden shops or online. You can also use sulfur dust in the same way.
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- Ryan also generously coats the freshly cut stem.
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- All those mesh bags saved from our bulb orders come in handy for storing tubers. These bags come in a variety of sizes and provide lots of air circulation. If you don’t have any mesh bags, any well-ventilated bags or boxes will do.
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- Ryan places each tuber clump in a bag and surrounds it with wood shavings. Some gardeners prefer storage mediums such as vermiculite, coarse sand, sawdust or sphagnum peat moss.
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- Because we also use wood shavings down in my stable, we have a good supply here at the farm.
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- Ryan adds enough shavings to keep the tuber dry. This is important as any moisture that causes rot could spread to other tubers.
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- We also save all the plastic crates that come whenever we order large collections of bulbs. I always try to reuse, repurpose or recycle everything at the farm.
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- The bags of tubers are then placed into a crate.
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- Ryan places the marker in the bag, so it is ready when spring arrives and time to re-plant the tubers.
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- It is important to ensure each bag gets ample air circulation – in the bags and in the crates. Overcrowding may promote rot.
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- Ryan does this process for each and every clump of tubers. He checks and trims any rotten pieces and feels each tuber. They should all feel firm to the touch.
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- Here’s Gavin carrying each crate down to the basement greenhouse. The ideal storage temperature is above freezing but below 50 degrees Fahrenheit.
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- Be sure to check the tubers a couple times over the winter, and discard any that have rotted. Environmental changes in the storage location, such as increased humidity or fluctuating temperatures, can still damage overwintering dahlia tubers. And then next spring, they’ll all be taken out again for planting – I can’t wait.
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