Preparing Your Dahlias for Frost, Dividing, and Winter Storage

The dahlia garden looks very different when you’re preparing for the end of the season than it does when you’re planting in spring.

After spending months growing, watering, staking, pinching and harvesting, eventually we have to prepare the plants for frost and the work that follows: digging, dividing and storing the tubers.

At Pedaling Petals, we grow a large and diverse collection of dahlias, so keeping each variety correctly identified and maintaining good sanitation during dividing are important parts of our process.

There are a few things we do before we ever start dividing.

1. Verify the Variety and label each plant before Frost

One of the easiest times to make a variety-identification mistake is at the end of the season.

Before we label a plant, we look at the bloom and verify that it matches the variety we’re expecting.

This is particularly important when you’re growing a large collection. Once the foliage and flowers are gone, you can’t simply look at the plant and remember what it was.

We use flagging tape and a garden marker to identify each plant.

The important part of our system is where we attach the label.

We tie the label to the bottom portion of the stem, below the point where we’ll make our final cut.

When frost arrives, we’ll remove the plant material above the remaining 4–6” stem. Because the variety identification is attached to the bottom of that stem, the label stays with the tuber clump.

That gives us a clear identification as we move from the garden into digging, dividing and storage.

Watch the process in the video below.

Lesson 9: Labeling Your Dahlias Before Frost

2. Get Your Dividing Supplies Ready Before You Need Them

We won’t begin dividing our dahlias until several weeks after this preparation.

But there’s no reason to wait until the day you start dividing to discover that you’re missing something.

Before we begin, we gather the tools and materials we’ll need and set up our dividing area.

For our process, that includes:

• ARS floral snips
• Mason jars for our sanitation solution
• A 10% bleach/water solution
• A stainless-steel cutting glove
• Clear storage totes and lids
• Vermiculite
• Garden markers

Getting everything together ahead of time makes the dividing process much smoother.

3. Sharp, Precise Snips Matter

We use ARS floral snips for dividing our dahlia tubers.

We like them because they maintain their sharpness and have a stainless-steel blade.

Dividing dahlias can involve making a lot of precise cuts. Having a sharp tool makes that work easier and gives us better control over where we’re cutting.

4. Sanitation Is Part of Our Dividing Process

When you’re dividing multiple dahlia varieties, you’re moving from one plant to another throughout the process.

That means sanitation becomes an important consideration.

We keep mason jars filled with a 10% bleach/water solution in a caddy at our dividing table. We use this solution to sanitize our snips between plants.

The goal is to reduce the risk of carrying virus from one plant to another on our cutting tools.

This is one of those small systems that becomes increasingly important as the size of your collection grows.

5. Protect Your Hands

Dahlia tubers can require a surprising amount of cutting, especially when you’re working through a large number of clumps.

We use a stainless-steel cutting glove from Dowellife to protect the hand holding the tuber while we’re working with the snips.

It’s a simple piece of protective equipment, but it’s something we want available before we start dividing.

6. Prepare Your Storage Containers

We store our divided dahlia tubers in clear plastic storage totes with lids.

We use totes that are readily available from Walmart.

Clear containers make it easy to see what’s happening inside the storage bin, while the lids allow us to keep the storage environment contained.

The important thing isn’t necessarily buying an expensive specialty storage system. It’s developing a system that works for the number of tubers you’re storing and allows you to keep them organized and monitored.

7. Have Your Storage Medium Ready

We use vermiculite as our storage medium.

Once the tubers have been divided and prepared for storage, the vermiculite will be used in our storage bins around the tubers.

If you’re planning to divide and store your dahlias for the first time, this is another material you’ll want to have on hand before you begin.

8. Use a Garden Marker That Will Stay Legible

Our variety identification system doesn’t stop when we label the plant in the garden.

We also use garden markers from DP Industries for identifying our tubers.

We specifically want a marker that won’t simply wash away with water or fade quickly from exposure to UV light.

When you’re storing dozens or hundreds of different varieties, a label is only useful if you can still read it later.

Preparing Now Makes the Next Step Easier

The dividing process may still be several weeks away, but preparation starts well before the first tuber is cut.

For us, that preparation means:

Verify the variety → label the plant → prepare the tools → establish our sanitation system → protect our hands → prepare storage containers → have vermiculite ready → make sure our labels will remain legible.

Lesson 10: Preparing to Divide & Store Dahlia Tubers

None of these individual steps is particularly complicated.

But together, they create a system that helps us move from a garden full of living plants to a collection of correctly identified tubers ready for winter storage.

We’ll begin dividing our dahlias in approximately 3–5 weeks, and we’ll continue documenting the process as we move through it.

Learn more on growing dahlias.