Dahlias are one of our very favorite flowers on the farm. They produce from Mid Summer all the way till a hard frost. They come in thousands of colors, shapes and sizes. I’m not sure why dahlias are not more popular as home garden plants.
Dahlias are grown from tubers, which look like potatoes. You plant them in early summer, after the last frost, and dig them up in the fall to store inside for the winter. If you live in a warmer zone like 7+ you probably can get away with leaving them in the ground as a perennial. Here in zone 6 we have to dig them up, but for all this work there is a reward. Each tuber that you plant in the spring multiplies into many tubers by the fall. You can then divide these tubers and have more for next year to grow or give away to friends.
This year we ordered about 50 dahlia tubers from a farm in Oregon. (There are many online retailers, just google it.) From those 50 tubers we harvested many many cut flowers over the summer, and now that the season is over we dug up the tubers for the winter.
Tubers multiply underground into a clump of tubers all connected together. Each one of these tubers can grow into another plant next year. From our 50 original tubers we ended up with 400 tubers in the fall! We plan to plant them all along with another 200 we ordered from Holland :). We are going to be swimming in about 600 dahlia plants this summer. It should be a sight to see!
There are many great resources online about how to dig and divide dahlias, so I will just give you a quick run-down.
After a hard frost the leaves of the dahla plant will wilt and turn black. Leave the roots in the ground for another 1-2 weeks. This cool weather tells the tubers that it is time to rest for the winter, and allows carbohydrates/ energy to be drawn from the leaves and stem into the tubers. After a week or two dig up the tubers being careful not to cut them or break them in the process. Take your time and dig about a foot all the way around the stalk.
After you dig them shake of the dirt and spray them off. If you look closely you should see a small “eye” near each tuber. This is where a new stem will grow next year. When you divide the tubers make sure to include an “eye” with each tuber or else it will not grow.
Now allow your tubers to dry for a few days in a cool dry place before storing them in peat moss or vermiculite in a storage container somewhere cool and dark. A cool basement or storage room is a great place to store them. Check on them every few weeks to make sure they are not rotting. If you find any that are squishy throw them out!
By no means is this the only way to dig, divide and store dahlia tubers. There are many ways to do it, the important thing is to find a way that works for you and stick with it.