As autumn arrives, it’s time to start thinking about caring for dahlias in the fall. These late summer showstoppers put on a stellar display of colorful blooms right up until frost. With proper care, the tubers can be overwintered and will return to bloom again next year.
In this guide, I’ll walk through the key steps for getting your dahlia tubers through winter in great shape. Follow these tips for storing dahlias successfully so you can enjoy their vibrant flowers season after season.
Why Fall Care is Crucial
Dahlias are tender perennials grown as annuals in cooler climates. The plants die back with the first hard fall frost. To save dahlias for next year, the tuberous roots must be dug up and stored over the winter.
With the right fall and winter care, dahlia tubers will survive cold months and resprout vigorously the following spring. Here’s why proper care is so important:
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Allows tubers to go dormant and store energy for next year’s growth.
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Protects tubers from rotting in wet winter soil.
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Avoids damage from extreme cold if tubers freeze deeply.
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Prevents tubers from starting premature growth in late winter.
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Provides opportunity to divide tubers for more plants.
If left in the ground, there is a strong chance the tubers will not make it through winter. Taking a little time in fall to care for dahlias ensures you will have healthy tubers for planting next year.
When to Dig Up Tubers in Fall
Timing is key when digging dahlia tubers in autumn. Here are guidelines for when to dig:
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Wait until after a hard frost blackens the foliage.
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Allow 1-2 weeks after frost for foliage to further die back.
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Tubers are mature once the stems darken and feel firm.
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Dig before ground freezes but not while soil is sopping wet.
Ideally, aim to dig dahlias 2-3 weeks after the first hard frost. The foliage acts as a marker, turning completely black once frost hits. Delay digging until you’re sure the plants have experienced frost.
How to Dig and Divide Dahlia Tubers
Here are the steps for safely digging up dahlia tubers in fall:
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Cut back frost-blackened stems to 6 inches above soil level.
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Carefully dig tubers using a garden fork, lifting the clump from below.
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Rinse off soil with a gentle spray, taking care around the necks.
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Allow clumps to dry upside down for a few days.
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Divide tubers by cutting with a sharp knife between visible growth eyes.
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Discard any damaged tubers or those without eyes.
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Dust cuts with sulfur powder or fungicide to prevent rotting.
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Keep divided tubers spaced apart until drying is complete before storage.
Dig carefully to avoid nicking or damaging the tubers. Never dig in extremely wet soil that will cling. Dry cured tubers store best, so allow all cuts to heal before storage.
Storing Dahlia Tubers for Winter
Proper storage conditions are key to keeping dahlia tubers alive through winter. Follow these tips:
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Store in a cool, dark place with good air circulation like a basement or crawl space.
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Ideal storage temperature is 40°F to 50°F. Avoid freezing or overheating.
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Use vented plastic bins, cardboard boxes, mesh bags, or trays filled with peat or vermiculite.
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Check stored tubers every 2-3 months for any signs of rotting.
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Keep tubers moderately moist but never soaking wet by spraying occasionally with water.
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Re-dust with fungicide if condensation appears within storage containers.
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Discard any tubers that are soft, moldy or shriveled. Healthy tubers feel firm and plump.
Providing cool, humid conditions around 40°F mimics winter conditions in the ground. Proper storage keeps tubers dormant and free of disease until spring.
Storing Tubers in Peat Moss or Vermiculite
An easy way to store dahlia tubers is buried in slightly moistened peat moss or vermiculite in plastic bins, boxes, or breathable bags:
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Add a 2-3 inch layer of peat or vermiculite to the bottom of the container.
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Place divided tubers in a single layer on top of the material.
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Cover with another 2-3 inches of peat or vermiculite.
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For larger quantities, layer in multiple bins with tubers separated by material.
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Keep peat or vermiculite slightly moist but not saturated while storing.
This protects tubers from temperature fluctuations and drying out. Just make sure any container has holes for airflow.
Storing Tubers on Trays or Racks
Slotted trays or wire racks work well for storing small quantities of dahlias:
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Allow cut tubers to cure for a few days first.
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Arrange cured tubers spaced apart on trays or racks in a single layer.
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Place containers holding the tubers in a protected cold area with 40-50°F temperature.
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Mist tubers occasionally with water to provide humidity.
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Ensure good air circulation around and under tuber containers.
Storing cut tubers on open trays allows for good airflow but requires more frequent moisture monitoring.
Overwintering Tubers in Pots
Another option is overwintering dahlia tubers right in their containers:
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Allow pots to experience frost and foliage to blacken.
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Cut back stalks to 4-6 inches.
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Place pots in an unheated garage or cellar before hard freeze hits.
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Check soil moisture monthly and water sparingly to prevent desiccation.
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Bring pots back outdoors in spring once danger of frost has passed.
This eliminates fall digging but requires an unheated space that doesn’t reach freezing where you can store planted pots.
Assessing Tubers in Spring
After overwintering dahlia tubers, examine them carefully in early spring:
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Look for firm, plump tubers. Shriveled or mushy ones won’t grow well.
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Check for new white shoots emerging from eyes or tips.
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Remove any damaged or rotting sections with a clean knife or shears.
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Soak healthy tubers in room temperature water for an hour before planting.
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Let cut ends of tubers dry and callous over for a few days before planting.
With care, 80-90% of stored tubers should survive winter. Damaged ones can be discarded while survivors are planted again.
Key Tips for Storing Dahlias Successfully
Here are the most important elements for successfully overwintering dahlia tubers:
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Leave plants in ground until well after first frost and dieback.
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Check that tubers are mature with firm stems when digging.
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Allow clumps and cut tubers time to cure before storage.
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Store in cool, humid conditions around 40°F. Never let freeze.
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Avoid excess moisture and drying out in storage containers.
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Divide and inspect tubers in spring, discarding any damaged ones.
With proper techniques for digging, dividing, drying, and cold storage, dahlia tubers will be vigorous for replanting when spring rolls around.
Enjoy Dahlias Year After Year
Caring for dahlias doesn’t stop when fall arrives. With some simple steps for overwintering the tubers, these beautiful blooms can be enjoyed again and again.
By providing well-timed and careful handling in fall along with proper cold storage conditions, dahlia tuber survival rates are high. Just be sure to avoid freezing, overheating, moisture extremes and pests.
The extra effort pays off when those first vibrant flowers open the following summer. Follow this guide for storing dahlias successfully so you can grow these garden favorites year after year.
If you HAVE NOT had a freeze:
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Make sure they freeze in the garden.
- Once they are dug up, make sure they don’t freeze where they are kept. An attached garage is usually pretty safe. Outbuildings that aren’t heated will usually freeze, so they’re not a good place to store things.
- Before putting them away, make sure they are VERY dry.
- Store dahlias in groups or split up in a cardboard box lined with newspaper. Bury the dahlias in peat moss. , this will give them added protection in storage. Place newspaper on the bottom of the cardboard box and fill it with peat moss. Then add dahlias, more peat moss, and so on until the box is full. This adds an extra layer of protection against freezing and keeps the humidity high.
Why do I have to let them freeze first:
5 dahlia growing tips in 5 minutes
FAQ
What should I do for my dahlias in the fall?
Should dahlias be cut back in the fall?
Is it OK to leave dahlias in the ground over winter?
How far down do you cut dahlias for the winter?
How do you grow dahlias in the fall?
Dahlias are a gorgeous addition to any garden. Here’s how to grow these beautiful fall blooms, including how to start them indoors, plant tubers outside, and cut the stems to encourage more flower heads.
How do you care for a dahlia plant?
Here’s how to care for them: 1.**Planting**: – **Timing**: Plant dahlia tubers outdoors in early spring, after the last frost and once the soil has warmed. – **Depth**: Depending on the variety,
Are dahlias hard to care for?
Dahlia flowers are a joy in the garden! They thrive in warm climates and attract pollinators through hot summers. They make stunning cut flowers, and care for dahlias is not hard at all. If you haven’t planted tubers in your garden to this point, now may be the time.
Are dahlias good for fall?
These gorgeous florals will brighten up your garden—and your day, if you cut and bring them indoors. It’s easy to fall in love with dahlias. Their massive flower heads are visual dynamite in a fall garden—and they look just as beautiful in a vase after you cut and arrange them.