By Nicole Forbes

education director at Dennis’

7 Dees Garden Centers




Daffodils, tulips and other spring-blooming bulbs are popping up all over town making us thankful for the hardy gardeners who planted the bulbs last fall.



If you missed the fall bulb planting season take heart, a new season is upon us.  Recent arrivals at local garden centers are lilies, begonias, dahlias, and other summer-blooming flower bulbs. Among these the queen of the summer cutting garden is the dahlia.

My first real experience with dahlias came from a woman who sold fresh-cut bouquets for $5 at a coffee-cart near where I worked. My initial ‘splurge’ on a bouquet turned into a second and then a third. Before long I had bargained with myself to skip my daily coffee purchase and replace it with the weekly pleasure I got from those bright, beautiful bouquets (and a few extra flower vases).

As a natural progression, I began to peruse garden centers for dahlias and look through catalogues from dahlia growers. Soon I had purchased several for my own garden.

With thousands of plants to choose from why would someone plant a dahlia? One simple reason is for the heart-stopping, jaw-dropping flowers that begin blooming in mid to late summer and last into the fall.



These plants make a stunning addition to your garden and produce fantastic flowers for cutting.  It is best to cut in the cool morning or evening. Place cut stems in 2-3” of very hot water (160-180 degrees) and allow to cool for one hour, then place in flower vases with fresh water. Cut flowers can last 5-7 days indoors.

Available in a multitude of colors, styles and flower sizes (from golf-ball size to dinner-plate), they also vary from low-growing border plants to 6 foot tall background plants.There is a perfect dahlia waiting for almost any sunny vacancy in your garden. Notice I mention ‘sunny’ location. Dahlias are fairly easy to grow, but require excellent drainage and need at least 4 to 6 hours of sun. Tubers (similar to bulbs) are available to plant in spring, May is best, or you can purchase already-growing plants later in the season.

Hardy in USDA zones 7-11 (Portland is zone 7), dahlias are prone to freezing and/or rotting over the winter if planted in heavy clay or poorly-drained soil. Here in the Pacific Northwest, some people dig their tubers up for winter storage, yet some prefer to leave them in the ground.

Potted plants can be tipped on their sides, collected into sheltered areas or tucked into garden soil for extra protection. I have never dug my tubers up for the winter and have only lost a few plants to winter-kill over the last 15 years. I prefer to gamble.

If you dig them up or if you have purchased new tubers this spring, wait until May to plant them in the ground, add a handful of bone meal in the bottom of the hole and lay the tuber horizontally at 4-6” deep before covering with soil and tamping down gently.



Do not water until first sprouts have come through soil.  A low-nitrogen fertilizer such as 5-10-10 should be applied about 30 days after planting and about monthly during growth.

If liquid fertilizer is used, be sure to keep nitrogen to a minimum. Try a ‘bloom’ type food with a higher middle number instead (phosphorous).  As the tender new leaves emerge, protect them from slugs; they love dahlias almost as much as you and I do.

There are many products available to deter slugs that use iron phosphate and are safe for pets and wildlife.

When young plants grow to about a foot tall, pinch back new growth to produce more branching. This would also be a good time to stake the plant to support all of its future blooms.  When installing your stake, take caution to avoid skewering the tuber.

I have seen ‘wild’ dahlias growing in Mexico where the genus is native to. Anthropologists believe they were grown and revered by the Aztec people centuries ago.

Nearly 50,000 varieties of dahlias are registered worldwide and there are 35 native species found growing in the highlands of Mexico and Central America.

Stop in to your local garden center to see which varieties might make you swoon.