Dahlias may be left in the ground over the winter; however, dahlias are susceptible to rot and/ or freeze. Dahlias are not hardy since they are a tuber (thin-skinned) and not a bulb.
If you wish to move or transplant your dahlias to a new location you may do so in the spring. Dahlias cannot be transplanted in the fall. Once you disturb their roots, you must store them for the winter.
If You Live in a Colder Area - Dig Up and Store
If you are in an area where the freeze reaches a depth of 4-6" or more, then leaving your dahlias in the ground is NOT an option. In many climates, dahlias must be dug and stored (see digging and winter storage information) as tubers cannot freeze. In warmer/mild states, including the Pacific Northwest, you may try leaving the dahlias in the ground over the winter. It is never a guarantee, but many customers find that this is a more successful route compared to digging and storing. Dahlias grown in containers or raised beds must be protected over winter as the tubers are more exposed to the elements (top and sides of the container or bed), leaving a greater chance of freezing. Containers should be moved to a garage or location where they will not freeze. If you are unable to move your containers, then we recommend digging and storing your tubers. Tubers planted in raised beds should be dug and stored over the winter.
If You Live in a Warmer Area - Leave in the Ground and Cover
Customers growing dahlias in hot climates year-round (Florida, Southern California, Hawaii, etc.) should dig, divide, and store their dahlias in a cooler/refrigerator for at least 90 days in the winter. Then plant them back out in the spring. They need a minimum of 3 months of rest between growing seasons. (Storage temperature should be 40-50 degrees). Be sure to check on the tubers at least once a month and follow our storage methods and packing medium guidelines.
Leaving Dahlias in the Ground over winter
If you choose not to dig up your dahlias, please remember that you will be at “Mother Nature’s Mercy”. Considered a “tender perennial,” dahlia tubers are the texture of a potato and are susceptible to freeze and rot. If your ground freezes 4+ inches deep during the winter months, this is not an option for you, as the tubers will freeze. For customers in mild climates that choose to leave them in the ground over the winter, we recommend after a killing frost or any time after November 15th, cutting the stocks down below ground level and covering your dahlia beds with plastic. Then you will want to add layers of material such as straw, leaves, or any type of material that will insulate and protect them from the winter weather, like blankets of warmth. If you do not dig in the fall, but would still like to divide your dahlias, (which we recommend at least every other year).
Divide Your Dahlias in the Spring
If you leave your dahlias in the ground over the winter or for multiple seasons without dividing them, you will need to thin the number of sprouts trying to grow in the spring. We recommend only allowing 1-2 main stalks to grow and pinching off all the other sprouts at ground level. If you do not remove these sprouts, your plant will be very weak as too many sprouts will be competing for sunlight and nutrients to grow.
