Arrival of delicate white, pink dogwood flowers a sign of summer’s onset

By Trevor Cameron / The Golfing Gardener

As we approach June, it is time to highlight one of the best flowering trees for our local area: the dogwood.

These trees’ brighten up our landscapes in May and June and offer additional interest in summer and fall, with showy berries on many and striking fall colors on all.

Traditionally, the dogwood represents the onset of spring in many parts of the country, and although the vernal equinox for us is in the rear-view mirror, we now get to enjoy these later-spring blooming specimens.

The genus cornus contains everything dogwood, including some useful Pacific Northwest-native groundcovers and shrubs, and some larger-growing, impressive species such as giant dogwood (cornus controversa) and pagoda dogwood (cornus alternifolia). The main species available to gardeners are listed below, though various cultivars of each can be found at local garden centers.

• Pacific dogwood (cornus nuttallii and cvs.): These are Pacific Northwest-natives that can often be seen in mixed forests both west and east of the Cascades. They are tall, stately trees with extra-large white flowers in May followed by nice fall color. However, these are a bit susceptible to dogwood anthracnose disease in our wet spring weather this side of the mountains.

• Eastern dogwood (cornus florida and cvs.): These are native to the eastern U.S., and they are what most folks think of when they picture a dogwood tree. They sport the classic rounded, four-petal flower in either pink or white and also have excellent fall color. I would never say these cannot be grown successfully in our area, but typically the healthier ones I see have full sun, good air circulation around them and are probably sprayed regularly as these are more prone to disease than any others in our rainy spring weather.

• Korean dogwood (cornus kousa and cvs.): These have more of a star-shaped flower with pointed petals and offer pink and white options, as well. They bloom a bit later through June and even into early July, then develop bright little red fruits in summer to fall, and finally shine with reddish fall color. These are extremely resistant to disease and easy to grow.

• Rutgers hybrids (cornus x and cvs.): Rutgers University has been kind to all gardeners, spending the last 40-plus years developing useful hybrids for home gardens with superior flower power and improved resistance to disease. There are plenty of worthy cultivars for our area, giving us excellent flowers and the disease resistance of the Korean dogwood.

As mentioned above, the major issue in Western Washington’s wet spring climate is dogwood anthracnose. This disease often infects trees in wet spring weather, causing the tips of foliage to curl and become discolored. If not treated, anthracnose may cause younger twigs to die back, which eventually affects flower-bud production and kills branches. As with almost all plant diseases, air circulation and exposure will always help, but some may also need to be sprayed.

All dogwoods can take a little more wet, tolerating heavier soils, and are great options for those who have fought (like me) verticillium wilt from less-than-ideal drainage. They are slower-growing specimens and bloom on old wood, so bud set occurs over the summer each year for flowers that bloom the following spring. Ideally, any pruning should be done right after flowering, although dead wood and structural issues can be corrected over the winter, as well. These are not drought tolerant, so be sure to irrigate trees a bit in dry summer months. Dogwoods are not heavy feeders by any means, but a dose of quality organic fertilizer this time of year will help optimize flower bud production.

The choices out there for specific cultivars and hybrids, as with most plants these days, can be somewhat overwhelming. Any variety of Korean dogwood is excellent and should minimize disease, as will any of the Rutgers hybrids. A few of my favorite varieties are listed below:

• Venus and Starlight: These are two superior Rutgers crosses of Korean and Pacific dogwoods, both with cleaner foliage and larger white blossoms from May into June. They grow a little more upright and larger than others, eventually reaching about 25 feet tall and 20 feet wide. Venus was the choice for me almost 20 years ago in my own yard, and it has been a spectacular, trouble-free specimen year after year.

• Stellar Pink: This is another Rutgers hybrid, blooming pink from May into June with the rounded petals like Eastern dogwood and the disease resistance of Korean dogwood. It grows to about 20 feet tall and wide with age. If you can find it, the variegated form is excellent with white and green foliage adding more interest in partial shade.

• Morning Sun: Speaking of variegation, this Korean dogwood is one of the best in my opinion, with bright yellow on green foliage and white, star-shaped flowers from June into July. It has a tidy habit to about 15 feet tall and wide, and it will achieve its best foliage color with some shade.

• Scarlet Fire and Rosey Teacups: These are two of the more recent introductions from Rutgers University, and both are simply stunning in flower. Each sports clean foliage and grows to about 20 feet tall and wide with age. Scarlet Fire has rich, deep-pink flowers, while Rosey Teacups has a nice medium-pink color.

• Milky Way: This is one of the best traditional white Korean dogwoods, sporting a bazillion smaller white star-shaped blooms in June and then showy little red fruits in the fall. It grows to about 20 feet tall and wide over time and has nice reddish-burgundy color in the fall. This literal galaxy of flowers is quite impressive in any landscape.

• Heartthrob: This excellent Korean variety was introduced in Oregon, with medium-pink flowers that last into July. These have a busy habit to about 20 feet tall and wide, and the foliage turns bright red in the fall.

Free class

Sunnyside Nursery in Marysville will host “Stop & Smell The Roses” at 10 a.m. on Saturday, June 1. For more information or to sign up, go to www.sunnysidenursery.net/classes.

Trevor Cameron is a certified professional horticulturist (CPH) and serves as general manager for Sunnyside Nursery in Marysville. He can be reached at sunnysidenursery@msn.com.