I was considering writing about Dahlia’s this week and when I came across an article about them in the new Martha Stewart Magazine, I acquiesced. First off, I don’t have a frame of reference on or about dahlias as I don’t remember them growing up nor have I come upon them much in my life. The article profiles florist, Erin Benzakein of Floret Flower Farm in Washington State’s Skagit Valley. What a labor of love and the pictures are heaven. One pictured variety in particular, Pale Fire, looks much like a large heirloom rose and has me convinced I should attempt growing one during next year’s season.
The dahlia is a genus of tuberous herbaceous perennial plants in the Asteraceae family native to Mexico and Central America. Their garden relatives include the sunflower, daisy, chrysanthemum and zinnia. There are 42 species of dahlias with many garden hybrids. There are thousands of varieties of dahlias and their blooms range from the size of a small pompom to dinner plate size. They come in a myriad of colors ranging from white to dark burgundy sometimes even presenting in color combinations.
Another feature of the dahlia family is that their blooms can resemble different kinds of flowers ranging from lilies, daisies, orbs and roses. Their variable size and flower forms are due to multiple chromosomes and genetic transposons that move around manifesting great diversity in this plant family. Many varieties grow tall enough to require staking. Dahlias like moderate climates, thus they thrive in slightly acidic (6.5-7) well-drained and well-watered soil planted where they get 6 to 8 hours of sun a day. They like morning sun best and should be protected from the wind, never easy in our climate.
Unlike other beautiful bloomers such as lilacs and peonies, dahlias, that start blooming in mid-summer, continue to bloom through the fall or until the first frost. Covering them on nights when frost is expected could extend their bloom even longer. They are also like some flowers in that the more you pick the blooms the more they will produce. This is nice if you like fresh cut flowers in your home like I do. It is also suggested you plant them in rows without competition from other plants, maybe on the side of your garden, especially if you are growing them for cut flowers. Planting dahlia’s at least a foot apart makes for a nice garden hedge as the plants will support each other but also mind the instructions that come with your plants. They require planting in a hole larger than the tuber or plant mixed with a little sphagnum moss and bone meal. To avoid root rot don’t water bare tubers at planting and skip the mulch as dahlia’s like warmer roots.
Once established, they require semi-weekly deep watering and like a low nitrogen fertilizer similar what you us for your vegetable garden. As they start growing pinch out 3-4 inches of the growing center which promotes bushier plants and increases stem count. Further along, remove smaller buds leaving the largest bud on the stem to encourage large blooms and, of course, dead head once blooms fade if you haven’t already taken them all into your house to enjoy. One downside to these beauties in our climate (Zone 4) is that their tubers require excavation in the fall, separation, overwintering in a cool dry place and replanting in the spring after the last frost. You might consider planting the tubers indoors a month or so before outdoor planting to give them a head start in the growing season. One advantage to this is that you can move your dahlias around from year to year until they find their happy place. Hopefully, this article has encouraged you to consider planting dahlias next season. It seems like the first challenge will be choosing from among the many enticing varieties you come upon while leafing through your favorite mail order catalog this winter or from those that become available at your local greenhouse in the spring. Enjoy the journey!