Caring for Dahlias in the Fall: A Complete Guide

Dahlias are absolutely stunning in the summer garden with their bright, colorful blooms But when fall arrives, it’s important to know how to properly care for dahlias so they survive the winter and return vigorously next year

In this guide. I’ll provide a complete overview of fall dahlia care including

• Why fall care is crucial
• When to dig tubers
• How to dig and divide tubers
• Storing tubers for winter
• Overwintering tubers in pots
• Spring tuber care

Why Fall Dahlia Care is So Important

Dahlias are tender perennials that are grown as annuals in cooler climates. When cold weather arrives in fall, the foliage blackens after the first hard frost. To ensure dahlias survive the winter, the tuberous roots must be dug up and stored indoors until spring.

With proper fall and winter care, dahlia tubers will remain healthy through the cold months to resprout again next year. Here’s why good fall care is crucial:

• Allows tubers to go dormant and store energy for next year’s growth
• Protects tubers from rotting in cold, wet soil
• Avoids freeze damage if tubers are left to freeze deeply
• Prevents premature growth if winter warms up
• Provides the chance to divide tubers for more plants

If left in the ground over winter, there’s a very high likelihood the tubers will die. Taking time in fall to properly care for dahlias ensures you’ll have vigorous tubers ready for replanting next season.

When to Dig Dahlia Tubers in Fall

Proper timing when digging up dahlia tubers in fall is absolutely key. Follow these guidelines to know when the right time is:

• Wait until after a hard frost fully blackens the foliage
• Allow 1-2 weeks after frost for foliage to further die back
• Tubers are mature to dig when stems darken and feel firm
• Dig before ground freezes but not when soil is overly wet

Ideally, plan to dig up dahlias 2-3 weeks after the first hard killing frost. Use the blackened foliage as an indicator that frost has occurred. Delay digging until you’re certain frost has hit and damaged the above ground plant parts.

How to Dig and Divide Dahlia Tubers

Follow these important steps when digging and dividing dahlia tubers in the fall:

• Cut back dead stems to about 6 inches above the ground after frost hits
• Carefully dig up tubers using a garden fork, lifting from underneath the roots
• Gently rinse off soil, taking care around tuber necks
• Allow clumps to dry upside down for several days
• Divide tubers by cutting between visible growth eyes using a sharp knife
• Discard any damaged tubers or those without eyes
• Dust cuts with sulfur powder or fungicide to prevent rot
• Keep divided tubers spread apart until fully dried before storage

It’s crucial to dig very carefully to avoid nicking or injuring the tubers at all. Never dig in extremely muddy soil where dirt will stick. Dried and cured tubers store much better, so allow divisions to heal before storage.

Storing Dahlia Tubers for the Winter

Providing proper storage conditions is vital for keeping dahlia tubers healthy and alive through the winter. Follow these tips:

• Store in a cool, dark place with good airflow like a basement or crawlspace
• Ideal temperature is 40°F to 50°F – avoid freezing or overheating
• Use vented plastic containers, boxes, mesh bags or trays filled with peat or vermiculite
• Check stored tubers every 2-3 months for any rotting
• Keep tubers moderately moist – spray with water occasionally
• Reapply fungicide if moisture condenses inside storage containers
• Discard any tubers that are soft, moldy or shriveled

Mimicking winter ground conditions around 40°F with high humidity keeps the tubers dormant and disease-free until spring planting season arrives.

Storing Tubers in Peat Moss/Vermiculite

An easy way to store dahlia tubers is burying them in slightly damp peat moss or vermiculite:

• Add 2-3 inches of peat or vermiculite in containers
• Place tubers in a single layer on top of the material
• Cover with another 2-3 inches of peat or vermiculite
• For large quantities, layer tubers and material in multiple containers
• Keep material slightly moist but not saturated
• Ensure containers have ventilation holes

This protects tubers from temperature swings while preventing drying out. Just be sure any storage box or bin has holes for needed airflow.

Overwintering Tubers in Pots

Another option is overwintering dahlia tubers right in their containers:

• Allow pots to experience frost and foliage dieback
• Cut back dead stalks to 4-6 inches above soil
• Move pots to an unheated garage or cellar before hard freeze
• Check soil moisture monthly and water lightly as needed
• Bring pots back outside in spring after all frost danger has passed

This eliminates fall digging but requires an unheated space between 40-50°F for storing the planted pots over the winter months.

Assessing Tubers in Spring

After overwintering dahlia tubers, carefully inspect them in early spring:

• Look for firm, plump tubers – shriveled or mushy ones won’t grow well
• Check for new white shoots emerging from the eyes and tips
• Remove any damaged sections or rot spots with a clean knife
• Soak healthy tubers in room temperature water for 1 hour before planting
• Allow cut tuber ends to dry and callous over for a few days before planting

With diligent care, 80-90% of properly stored tubers should survive winter. Discard any damaged tubers while healthy ones can be replanted for the new growing season.

Key Tips for Storing Dahlias Successfully

Here are the most critical points to keep in mind for successfully overwintering dahlia tubers:

• Leave plants in the ground until well after the first frost
• Check tuber maturity – stems should be firm when digging
• Allow clumps and divisions to cure before storage
• Maintain ideal 40-50°F temperature during winter storage
• Prevent excess moisture or drying out
• Divide and inspect tubers in spring, removing any rotted ones

Following proper techniques for fall digging, drying, dividing, and cold storage will result in vigorous dahlia tubers ready for replanting next spring.

Enjoy Dahlias Year After Year

Caring for dahlias doesn’t stop when fall and winter come along. By taking simple steps to properly overwinter the tubers, you’ll have vibrant, beautiful blooms coming back every year.

With well-timed and careful handling in fall paired with correct storage conditions, dahlia tuber survival over winter is very high. Avoid freezing, overheating, and excess moisture or drying out during storage months.

A little extra care in fall pays off tremendously when those colorful flowers reemerge the following summer. Follow this guide for storing dahlias successfully so you can grow these garden favorites season after season.