Dahlias are the dazzling showstoppers of mid to late summer gardens, rewarding us with vibrant blooms in every imaginable colour and shape.
But here’s the catch—these beauties are not winter-hardy in our cold prairie zones. Once frost hits, they’re as vulnerable as a tomato plant in a blizzard.
If you want to enjoy your dahlias year after year, you’ll need to dig them up and store the tubers properly through the cold months. Let’s explore the process of preparing and storing Dahlia tubers so you can enjoy their splendour year after year.
Why Store Dahlia Tubers Over Winter?
Dahlias, with their flamboyant blooms, are native to the milder climates of Mexico and Central America.
While they thrive in summer’s warmth, dahlia tubers are surprisingly delicate. Exposure to extended freezing temperatures can spell disaster for their tender roots, turning them to mush long before spring arrives.
For gardeners in temperate or cold climates, digging up and storing dahlia tubers is vital to ensure tuber viability for a spectacular display next season.
Two Key Goals for Dahlia Tuber Storage
The secret to successful Dahlia tuber storage rests on two key goals:
· Dormancy: Keep tubers cold enough to remain dormant, but not so cold that they freeze.
· Maintaining Hydration: Shield tubers from shrivelling due to dehydration or rotting from excess moisture or poor airflow.
Achieving this balance requires a little know-how, a bit of intuition, and an appreciation for the uniqueness of each dahlia tuber.
When to Begin Preparing Dahlias for Winter Storage
Dahlias don’t need to be dug up at the first sign of autumn chill. Instead, let your dahlias continue growing in their pots or in the ground until the first hard frost causes the foliage to lose its turgor. This final cold burst allows the dahlia tubers to store up energy for next year’s bloom.
Once frost has struck, use clean, sharp pruners to cut back the stems to 10-15 cm (4-6″) above ground. This stub helps you locate the tuber clumps and provides a handy handle for lifting.
How to Prepare Dahlia Tubers for Storage Step by Step
Follow these step by step instructions to settle your Dahlia tubers in for a cozy winter nap:
1. Digging Up Dahlia Tubers
Using a sturdy garden fork or spade, gently loosen the soil around each plant. Work carefully to avoid slicing into the tubers.
Lift the clump, shake off excess soil, and behold the gnarled, earthy treasures that grew all summer long.
Pro tip: Label your plants before you dig! Once they’re out of the soil, it’s impossible to tell which was the deep crimson ‘Arabian Night’ and which was your caramel pink ‘Café au Lait’. I use a waterproof tag tied loosely to the stem of the dahlia.
2. Cleaning and Curing
After they have been dug out of the ground, the first step is to knock or brush off excess soil.
I do not recommend washing or rinsing the tubers with water, as Dahlia tubers are prone to rotting if left too wet.
Lay them out on newspaper or trays in a cool, dry place with good air circulation for several days (5-10) to allow them to cure and heal any cuts that may have occurred in the digging process.
This air time hardens their skins, providing a natural barrier against rot.
3. Dividing (Optional)
You can store whole clumps over winter, but they take up more space.
If you’d rather divide in the fall, use a clean, sharp knife or pruners and make sure each division has at least one visible eye, which is a small, round growth point, near the crown. The crown is where the stem and roots meet.
Some gardeners prefer dividing in spring when the eyes are more visible. Either works—it’s personal preference.
4. Packing for Storage
Dahlia tubers appreciate a Goldilocks storage approach—not too wet, not too dry.
Nestle the tubers in boxes or paper bags filled with just-damp potting soil, peat moss, or shredded newspaper.
Avoid plastic bags or bins, which trap moisture and can accelerate rot. Label each variety so you know what’s what next spring.
5. Finding the Perfect Storage Spot
Dahlia tubers need a cool, dark, and slightly humid place to overwinter—think 4–10°C (40–50°F). Too warm and they’ll shrivel; too cold and they’ll freeze.
Basements, cold rooms, unheated closets, or insulated, heated garages that stay above freezing work well.
Check on your tubers every month or so: if they’re shrivelling, mist lightly with water; if they’re soft or mouldy, remove affected tubers to protect the rest.
6. Wake-Up Call in Spring
When the days lengthen in early or mid-March, it’s time to wake your Dahlias.
Bring them out of storage, inspect them one last time, and pot them up indoors in a well-draining potting mix. Place the pots in a warm, sunny spot to give them a head start.
If you prefer, you could wait to plant them directly in the garden after the danger of frost has passed in mid-May, but that will significantly delay their flowering.
Anticipating a Grand Return
Whether you’re a novice or a seasoned gardener, storing Dahlia tubers is a rewarding tradition. With a bit of care, you’ll be greeted by a riot of colours and a sense of accomplishment when your Dahlias burst forth, stronger and more beautiful than ever.
More to Explore
- The Ultimate Guide to Fall Bulbs in Canada
- How to Prepare Your Garden for Winter
- 4+ Great Fall Blooming Perennial Flowers for the Prairies
- How to Prepare Perennials for Winter
- Fall Mums 101: Your Complete Guide to Selecting and Caring for Fall Chrysanthemums
- How to Plant Garlic for Maximum Growth and Yield
© Sharon Wallish Murphy © Gardening with Sharon
