How to Overwinter Dahlias- PART 2... STORAGE
I frequently receive questions about how to care for dahlias during the winter. Since there’s no single solution, the key is discovering what works best for you. In Part 2 of my Dahlia Ramblings, I explore different storage techniques and preparations, offering guidance to help you find the best approach for your dahlias this winter.
MISSED PART 1? – “Digging Dahlias” Check it out HERE!
Prepping Dahlias for Storage
There’s a couple key things that need to be done prior to putting dahlias to rest for the winter and/or dividing clumps. They are:
- Remove Non-Viable Tubers: Cut off any root pieces, tiny “pencil” tubers, or those with broken necks. These will not be viable for replanting next year.
- Inspect for Rot: Carefully check each clump for signs of rot. If you find any, use a clean knife to cut it out entirely—leaving any rot can ruin your tuber while in storage. Rot is often found in the stem, so inspect it closely.
- Tip: If you need to cut pieces out or if there’s damage from digging, sprinkle cinnamon on the exposed areas to help seal them and reduce the risk of further rot.
- Dry Thoroughly: Ensure all dahlias are completely dry before storing. Dampness can promote mold growth.
Cut off all “Pencil” tubers and roots. Photo Credit: Summer Dreams Farm
Rot in Dahlias. MUST CUT OUT any black/Dark Brown Spots showing signs of rot.
To Divide or Not to Divide: Fall vs. Spring
Dividing dahlias is a topic of debate. Both fall and spring have their benefits:
Dividing in the Fall:
- Easier to Cut: Dahlia tubers are softer in the fall, making them easier to cut.
- Saves Space: Dividing reduces the size of each tuber, allowing you to store more in less space. It also helps eliminate unviable parts like damaged roots and stems.
- Less Risk of Rot: When you divide, you remove the “extra” parts, often where rot thrives. Storing dahlias as whole clumps can sometimes lead to the entire clump rotting.
- Less Work in Spring: By dividing in the fall, your tubers are ready for planting as soon as spring arrives.
- Better Inventory Control: You’ll know exactly how many tubers you have by the time winter ends.
Dividing in Spring:
- Easier to Identify Eyes: By spring, the eyes are clearly visible and sprouting, helping you avoid cutting into them accidentally. This can prevent the loss of viable tubers.
- Less Work in Fall: After the busy growing season, fall can feel overwhelming, and dividing then may feel like an extra chore. Spring division is often more manageable when energy and excitement for the garden are renewed.
- Simpler Storage: Storing whole clumps can be easier since they’re simpler to label and handle.
- More Reliable for Sales: Dividing in spring guarantees that you can sell viable tubers, as the eyes will be clearly visible. In fall, you can’t be sure if the tuber will sprout, and you’re trusting the buyer to store it properly, which can lead to complaints if something goes wrong.
One More Alternative...Do Not Divide At ALL!
Does dividing intimidate you? You’re not alone. Feel free to forgo dividing altogether and plant those tuber clumps whole. While you do sacrifice multiplying your stock, leaving the clumps whole will save a lot of time and ensure that you will have some eyes come next season.
Please note it is advised to divide plants at least every 3 years.
Labeling Your Dahlias
Whether you divide your dahlias or store them in clumps, labeling is essential.
- For Clumps: If you used construction tape or other labels around the stems, leave them on. However, labels can sometimes fall off during storage, so it’s wise to also label the tuber directly using a permanent marker.
- For Tubers: Write directly on the tuber. Ensure tuber is completely dry or else it will be difficult. The more blunt the writing implement, the easier because it’s less likely to pierce skin.
- Container Alternative: You can store all clumps or tubers of the same type in one container and label the container instead.
RECOMMENDED TOOLS:
- Sharpie Marker
- Indelible Pencil
- Rubber Stamps
- Paint Marker
I personally recommend the Sharpie Pro or Milkwaukee Inkzall for their ability to mark on almost any surface.
Storage Requirements
Dahlias are picky when it comes to storage conditions, much like Goldilocks. They need to be stored at a cool enough temperature to prevent premature sprouting but not so cold that they freeze. The ideal conditions are:
- Temperature: 40-50°F (4-10°C)
- Humidity: 70-90% relative humidity
- Ventilation: Adequate air circulation to prevent moisture buildup
Great storage locations include a cool cellar, an attached garage, or even a dedicated refrigerator.
Storage Mediums
The medium you use to store dahlia tubers plays an important role in their preservation. Here are some popular options:
- Sterile Peat Moss: Retains moisture without becoming too wet, but it’s a non-renewable resource.
- Vermiculite: Lightweight, helps maintain moisture, but can be expensive.
- Sawdust: Good for insulation and moisture control, though it may be hard to find.
- Sand: Heavy, retains moisture, but can lead to rot if it retains too much moisture.
- Untreated Wood or Paper Shavings: Easy to handle, provides good air circulation, and is inexpensive, but too much air can dry out the tubers.
Remember, it’s always best to use sterile mediums to minimize the risk of pests, fungi, and bacteria.
The Saran Wrap Method*
Although I have never personally tried this method, I know many people who use plastic wrap to over-winter their dahlias. The plastic wrap method entails tightly wrapping each individual tuber in multiple layers your standard grocery store plastic aka “Saran Wrap.” A great example of how to do this is shown in Floret Farm’s “Discovering Dahlias” (also a great dahlia resource altogether!)
Entire Dahlia clumps can also be wrapped, although this method is certainly not tried and true, but can be used in a pinch.
*PS-This method is discouraged by our local Dahlia Chapter, the National Capital Dahlia Society. This technique is popular but can trap moisture, leading to a higher risk of rot. It’s not recommended in areas with high humidity such as the DMV.
Peat Moss, Saw Dust, Vermiculite, Sand…I’ve tried them all!
Saran Wrap Method. Photo Credit: National Dahlia Society
Storing Dahlias in Planters
And here is where I directly contradict what I just stated above about always growing in a sterile medium. 🙂
For the last three years, I’ve successfully stored dahlias in large planter pots, leaving them in soil. While this method works well, here are some things to consider:
- Inspection: It’s harder to check the tubers, as they’re buried deep in soil.
- Non-Division: The tubers won’t be divided unless you dig them up in spring.
- Pests and Disease: Planter storage may expose dahlias to pests or diseases, as they’re not stored in a sterile medium.
- Early Sprouting: Dahlias in pots will start sprouting earlier, so be prepared to manage that.
Monitoring Your Stock
Check on your dahlias every couple of weeks to ensure they’re in good condition. Things to look out for:
- Excess Moisture: Too much moisture can cause rot. If your tubers are too wet, increase air circulation.
- Excess Dryness: Too little moisture can cause shriveling. A light sprinkle of water can help, but be careful not to overdo it.
- Rot: If you spot any rot, remove it immediately to prevent it from spreading.
- Mold: If mold appears, remove the affected areas and consider sprinkling cinnamon or a fungicide to prevent it from spreading.
Dahlia tubers: Organized, Tucked away and Cozy for Winter storage
Garage Full of Potted Dahlias. These will bloom EARLY next season!
Final Thoughts
Proper storage and care of your dahlia tubers are essential to ensure healthy plants and vibrant blooms in the following season. Whether you choose to divide your tubers in the fall or spring, the key is to provide the right conditions—cool temperatures, high humidity, and good ventilation—while also selecting the appropriate storage medium to maintain moisture and prevent rot. Labeling your tubers accurately and checking on them periodically will help you stay organized and ensure that everything stays in optimal condition.
It’s important to remember that, despite your best efforts, some loss of stock is inevitable each year. A small percentage of tubers may not survive the winter, whether due to rot, pests, or other factors. This is a normal part of gardening, and while it can be disappointing, it’s essential to keep a positive outlook and learn from each season’s experience.
Ultimately, the method you choose for storing your dahlias comes down to your personal preferences, time, and resources. Whether you take the time to divide them in the fall for better space efficiency or opt for the simplicity of spring division, both methods can yield great results. With a little attention to detail, your dahlias will be ready to thrive in the garden again next season, delivering a spectacular display of color and beauty
Happy Gardening!
Stay Tuned for PART 3- Dividing and Pre-Sprouting Tubers
Copyright 2024 (C) Branches & Batches Flower Farm
