Often the star of the garden, dahlias are one of the most beloved types of flowers, coming in various colors, shapes, and sizes. It’s now that time of year when dahlias are past their peak, and it’s time to start digging them up. If you’re wondering when to dig up dahlias, fortunately, they’re pretty flexible.
Dahlias should be dug up once the plant starts to yellow/blacken and die naturally or due to the first killing freeze of the season. You want to keep the dahlias in the ground for as long as possible to allow the dahlia tubers to mature. That said, they need to be dug up before the soil freezes, which can kill the roots.
There are a few factors to consider when digging up dahlias to ensure that you can enjoy their beauty again next year!
When to dig up dahlias
Dig up dahlia plants once the top foliage starts to die back due to cold weather. This may change depending on where the dahlia is planted. If the ground starts to freeze with a thin crust, dig up the dahlia as quickly as possible before the top foot of the ground freezes hard and kills the tubers.
If the dirt doesn’t freeze, attempt to keep the dahlia in the ground for as long as possible. This will allow the dahlia tubers to mature. The more mature the tubers, the likelier they will survive winter storage and be replanted the next growing season.
Do not cut dahlia stems before digging up the plant, as the hollowness of the stem will collect water and encourage further rot and decay, harming the plant.
Dahlias are not frost-tolerant. Every fall you will have to dig the bulbs up, store them for the winter, and then replant them next spring.Connie’s Dahlias: A Beginner’s Guide, by Connie Thompson
To properly care for and dig up dahlias, you will need a garden fork, shovel or spade, a bucket or container to transport the tubers, a soft brush to clean tubers up, and tarp or old newspapers to sun out the tubers prior to storage.
During winter storage, you will need a dry container to store tubers and sawdust, peat moss, dry sand, and wood shavings to create bedding.
How to dig up dahlias
You’ll need to use a spade or shovel when digging up dahlias. Start by making a hole around the base of the dahlia and loosening the soil while being careful not to cut into the tuber itself. Dahlia tubers are very delicate, so be careful!
Once you have the hole dug, slowly rock the plant back and forth with your hands until it comes loose from the dirt. Carefully lift the plant from the soil and place it in a container or bucket. You will use this to transport the dahlia when you are done.
Storing dahlia tubers and tuber clumps
After you dig dahlia tubers out of the ground, gently shake off any excess dirt and debris from their roots before placing them in your container or bucket. Then, use a soft brush to brush away any dirt still clinging to the tuber. For any tougher dirt clumps, gently use a garden hose to wash it away. It is very important to remove as much soil as possible, as dirt contains microorganisms that will harm the tubers during storage.
After brushing off all of the dirt, place the dahlia tubers on a thick layer on newspaper or paper towels and set them out in direct sunlight for about an hour. This will allow them to dry before storage.
Once dried, you can store dahlia tubers for winter in a cool, dark place. They should be placed in a container with bedding of sawdust, peat moss, dry sand and wood shavings.
Make sure to inspect tubers monthly and remove any tubers that have rotted or begun to mold, since rot can infect otherwise healthy tubers. When storing them, make sure there is good air circulation and avoid packing them too closely together.
If you live in an area that sees ground freeze in the winter, you must dig dahlias before the ground freezes (just after the first hard frost). Doing so will prevent the tubers from dying.
When storing tubers, it is important that adequate circulation is provided to prevent rot. You must also keep tubers dry and stored in a cool, dark place.
FAQs about timing for digging up dahlias
How long can dahlia tubers stay viable when stored?
Dahlia tubers can usually be stored at home for 3-6 months. It is important to constantly check the tubers throughout winter because if stored for too long, they will dry out and potentially die. Make sure also to remove any tubers that are showing signs of rot.
What is a dahlia tuber?
A dahlia tuber is the thick, fleshy root of the plant that stores all the nutrients and water the plant needs to survive. When the plant dies back to the soil line in the fall, the dahlia roots or tuber is all that remains of the plant. These tuberous roots can be replanted in the spring to grow dahlia flowers again.