Dahlia: My Favorite Summer Bulb
Posted: May 9, 2015
These thrifty gardeners of old would buy one new dahlia in spring, divide it the following year, and trade with neighbors to increase their collection at minimal cost. Today, this bulb (known as a tuber) has become fashionable again as witnessed by the availability at local garden centers.
Although dahlias require some work, they reward the gardener as these tubers, which look somewhat like skinny, dried potatoes, continue to produce blooms from mid-July through the fall, even into November, weather permitting. To extend their season, I cover them with old sheets when the first frost is predicted, because generally there will be more warm weather before they are taken by the much colder weather to follow. After the foliage is blackened by the frost, I cut most of the top off, dig them up, store them in my unheated garage, and replant them in the spring. But they could be treated as “annuals” and thrown away at the end of the season.
A quick tip I learned a few years ago was to plant the tuber in a container and store the whole container in an unheated garage or cellar, about 40 to 50 degrees. I like dahlias in containers because when spring perennials disappear, the container can be placed in the empty spot and enjoyed the rest of the season. They can be moved around the garden for a spot of color where needed.
One good guideline is to plant dahlia tubers in the same time frame as you would a tomato. If you are planting in containers, you can start the tubers indoors in good light about a month before planting time, and you have a small plant with a head start. Choose a site with good drainage and partial to full sun. They do very well in my garden where I get 4-5 hours of sun if I’m lucky. Because of this, I stay away from the largest type, dinner plate, and stick to the small to medium-sized dahlias.
Tomato cages can also be a simple approach to staking for the taller dahlias. A tip I use is to place a hollow 1/2-inch black plastic piping about 3 feet long (18 inches into the ground with another 18 inches above ground) next to the tuber. I place a green stake inside the pipe changing the stake as the dahlia grows.
Finally, the good news for dahlias is that they are low on the deer’s list of favorite foods. Although they may nibble at them, they will opt for better selections in your garden.For more in-depth information on dahlias, visit the American Dahlia Society’s web site.
- Luzerne County Master Gardener