How to Dig, Store, and Divide Dahlias- PART 1 - Branches & Batches Florist and Flower Farm

How to Dig, Divide, and Store Dahlias- PART 1

I often receive inquiries about how to dig dahlias and care for them during winter. There’s no one-size-fits-all method; it’s often about finding what works best for you. Here’s a guide to help you decide whether to dig up your dahlias or leave them in the ground, and how to proceed if you choose to dig.

To Dig, or Not to Dig...That is the Question!

“Do I really need to dig up my dahlias?” It’s a question I hear a lot. The answer is…It depends!

Zone 8 and above: No digging required! Dahlias can survive winter in the ground and return reliably each year. However, tubers multiply annually, which can lead to overcrowding, poor blooms, and declining plant health. Even in warmer zones, it’s recommended to dig up dahlias and divide every 3 years to maintain healthy growth.
Zone 7 and below: In colder regions, digging up dahlias is recommended to prevent tubers from freezing. Some gardeners in Zone 7B (like central Maryland) and even Zone 6 have successfully overwintered dahlias by keeping them warm and dry. For instance, Jenny Love from Love’n’Fresh Flowers in Pennsylvania uses this method in Zone 6b/7. However, even with precautions, freezing temperatures can render tubers non-viable, so proceed with care.

Personally, I dig up my dahlias each year to avoid the risk of losing valuable tubers due to unpredictable weather.

Pros and Cons

Advantages of Overwintering Dahlias in the Ground

Less manual labor: No digging, cleaning, or dividing required.
Less risk of storage failure: Tubers are left undisturbed.
Earlier blooms next season: Plants can get a head start.
More blooms per plant: Properly divided dahlias every few years may produce more flowers in a given year.
Cost savings: No need for materials or labor to dig and store.
Simpler organization: Avoid the hassle of labeling and keeping track of stored tubers.

However, even with these advantages, overwintering in the ground still requires extra care in colder zones to ensure the tubers stay warm and dry.

Advantages of Digging Up Dahlias

While overwintering works for some, there are clear benefits to digging your dahlias:

Protection from freezing and dampness: Critical for Zones 7 and below.
Avoid critter damage: Voles, moles, and squirrels often target buried tubers.
Plant health and propagation: Dividing tubers ensures healthier plants and allows you to multiply your stock.
Cull underperforming tubers: You can discard or give away weaker or unhealthy ones.

How to Dig Dahlias

Digging dahlias is straightforward with the right tools. I recommend using a large pitchfork rather than a shovel, as it’s less likely to damage the tubers. Here’s how to do it:

1. But FIRST! Tag your Dahlias: If you like to keep track of your dahlias, make sure you label them prior to digging. I like to use flagging tape that can be cut to size and tied around the stem. You can also use nifty tree tags like these.
2. Loosen the Soil: Work your way around the clump, coming in from multiple sides and digging wider and deeper than expected. Tubers grow during the season, so they’re larger than when planted.
3. Dig Below the Clump: Insert the pitchfork well below the tuber mass to avoid slicing the tubers
4. Gently Lift the Clump: Once the soil is loosened, using the pitchfork for leverage, lift the clump carefully from below. You can use the dahlia stem to help guide, but don’t yank up on it. That will lead to more breakage.
5. Shake it Off (Just Shake it Off, oh oh oh!): Once the clump is out, shake off excess soil and remove any hitchhikers (like worms) hiding between the tubers. If possible, dig in dry conditions to make the process easier.

If you accidentally nick a tuber, don’t worry! As long as the majority of the tuber is intact, it’s still viable. My first year digging dahlias, I used a shovel and ended up damaging nearly all my tubers—definitely not ideal. Use that pitchfork if possible!

Below is a video from one of my favorite flower farmers that I follow, Lori Hernandez from Three Acre Farm. Check it out!

Washing, Drying, and Curing Dahlias

After digging your dahlias, the next step is cleaning and curing them for storage:

Wash the Tubers: Spray off dirt using a hose. I recommend placing them on a draining surface like crates to allow water to flow away. Also- if you are old like me, wash them on an elevated surface to spare your back!
Dry the Tubers: Find a cool, dry spot to let them dry for 24–48 hours, but ensure it’s a spot where temps don’t drop below freezing! An attached garage or basement is a good place. Fans can accelerate the drying process.
Avoid Porous Surfaces: Tubers placed on concrete may lose moisture and dehydrate. While I’m unsure of the science behind this, I prefer to err on the side of caution; I use cardboard on my garage floor for this purpose.
Ready to Store (or Divide): Once the tubers are completely dry, they will be ready to store or divide.

Spraying down dahlias during a rain storm.

Winter 2024 ‘The Hostile Takeover of the Garage”

Final Thoughts

Whether you choose to dig or overwinter in the ground, understanding your growing zone and taking proper precautions will ensure healthy dahlias next season. For colder zones, learning how to dig dahlias, prepare and store correctly can save your tubers and keep your garden thriving.

Happy Gardening!