You can save dahlia bulbs next year by digging them in fall, curing them for a few days, and storing them in a cool spot between 40-50°F (4-10°C). Most people call them bulbs but dahlias grow from tubers which are swollen underground stems. Either name works and the process stays the same.
I started saving dahlia tubers six years ago with mixed results at first. My first year only 50% made it to spring because I stored them too wet. By year three I hit 85% survival after adjusting my method. Now I save about 90% of my collection each winter using what I have learned.
Tubers work like batteries for your dahlia plants. They store food and water during the growing season and go dormant when winter comes. Penn State notes that tubers need at least 120 days in the ground to mature enough for good storage. Dig too early and they lack the reserves to survive winter.
To preserve dahlia tubers well you need to give them the right storage conditions. Pick a medium like vermiculite, peat moss, or wood shavings that holds some moisture without staying wet. Each tuber should have space around it so air can flow and rot cannot spread between neighbors.
The American Dahlia Society says each viable tuber needs three things to grow next year. It must have part of the crown where stem meets root. It needs an intact neck that connects crown to body. And it must have at least one visible eye or growing point. Tubers missing any of these parts will not sprout.
Start the saving process after your first hard frost kills the foliage. Wait about two weeks before digging so the tubers can draw back nutrients from the dying stems. Cut stems to four inches, dig carefully with a fork, and rinse off the dirt so you can inspect each tuber for damage.
Cure your tubers for four to five days at 60-70°F (15-21°C) before final storage. This drying time lets cut surfaces heal and skin toughen up. Skip this step and your tubers will rot fast once stored. Set them on cardboard or newspaper and flip them halfway through.
To keep dahlias year to year takes some attention through the winter months. Check your stored tubers once a month and remove any that show soft spots or mold. Mist any that look shriveled to add back moisture. These quick checks take ten minutes but save tubers from silent death.
In my experience some varieties store better than others over the long term. Dinner plate types with their large tubers tend to be tough savers. Smaller pompon and ball varieties sometimes shrivel more in storage. Give the smaller types a bit more moisture in their storage medium to help them through.
Come spring your saved tubers will sprout eyes as temps warm up. Plant them outside after all frost danger passes and the soil reaches 60°F (15°C). Space them about two feet apart and cover the tubers with three inches of soil. Your saved dahlias will grow back stronger each year as the tubers multiply.
Read the full article: Dahlia Tuber Storage: Keep Your Tubers Alive
