I recently discovered the bunchberry ( Cornus canadensis), a ground-hugging dogwood, and could not resist it. The leaves resemble those on their bigger relatives but they are much smaller. The plant only grows about eight inches high and has traditional blooms.
When I looked for information on this little guy, I discovered that the dogwood family (Cornaceae) is quite large. Dogwoods thrive in the temperate zones of the Northern Hemisphere. Some are native to the West Coast. The bunchberry is even found in Greenland.
The bunchberry likes cool, moist, shady areas. Instead of having a taproot, it has many fibrous roots that grow from a rhizome or mass of roots that can produce new plants. Its small blooms bear edible berries in fall. I transplanted mine to a large pot and it has almost filled it. Some of the outer branches are creeping across the soil.
Many dogwoods are native to the Western U.S. They thrive in the shade of other trees and have showy white blossoms. I recall driving through Virginia in spring years ago and seeing dogwood blooms floating in the shade of the trees overhead. The Western dogwood is native to the redwood forests near Mendocino. These trees give a beautiful display in May.
The most common ones in our Napa Valley gardens are the Eastern dogwood (Cornus florida), Western dogwood (Cornus nuttallii) and red twig dogwood (Cornus alba 'Elegantissima'). I have several varieties growing in my garden but one I especially love is a small bush variety that I have not been able to identify. It was given to me many years ago by a nurseryman and I have taken many cuttings. It reaches about three feet in height and every spring puts out many blooms that look like a spray of stars, similar to the flowers on a red twig dogwood.
Another dogwood in my garden is Cornus mas, also known as Cornelian cherry, European cornel or Cornelian cherry dogwood. I kept expecting to see big white flowers on this tree but what finally appeared were small yellow flowers. None of these flowers have ever turned into fruit although I have read that the tree produces small red berries. This tree grows vigorously and appreciates an annual severe pruning which I often do in summer.
Dogwoods do not do well in either dry soils or areas that flood. They like fertile soil and will slowly die in the wrong conditions. Death by root rot from excess soil moisture is one of the most frequent causes. If the soil does not drain properly, little can be done to correct the situation.
Dogwoods are subject to anthracnose and crown canker disease, both fungal diseases. Even imported dogwoods are susceptible. Avoid damaging the trunk of the tree as that is how these diseases often enter. Certain borers also attack dogwoods. However, in all the years I have had dogwoods in my garden, the only significant pest I've seen is some scale on the newer growth. I scrape them off with my fingernail rather than use chemicals.
In warmer climates dogwood bark can sunburn, causing the tree to decline and die. The damaged bark invites borers, which kill the tree. If you find borers in branches or limbs, cut the wood off below the infestation and dispose of it. Do not leave it in your garden. If the borers have invaded the main trunk, the tree may be a loss. Over the years, breeders have developed hybrid dogwoods that are resistant to some of these diseases and pests.
In the fall, dogwood leaves produce a blaze of color ranging from pink to burgundy-orange to blood red. If you are looking to add autumn color to your shade garden, consider the many dogwood options at local nurseries.
Library Talk: Join UC Master Gardeners and Napa County Library for a free talk on “Trees: Moving to Greener Pastures” on Thursday, January 5, from 7 pm to 8 pm, via Zoom. Learn about the intricate subterranean fungal network that supports trees. Imagine with us what needs to take place for a community of trees to meet the challenges of our changing climate. Register to receive the Zoom link at https://ucanr.edu/2023JanTrees&FungiLibraryTalk
Workshop: Join UC Master Gardeners of Napa County for a workshop on “Winter Rose Care & Pruning” on Saturday, January 14, from 10 a.m. to noon via Zoom. Learn how to prepare your roses for the upcoming growing season and how to choose the right rose for the right place in your garden. Attendees will be invited to join a hands-on pruning workshop at Napa's Fuller Park rose garden on Thursday, January 19, from 10 a.m. to noon to practice pruning one-on-one with a Master Gardener. Register at https://ucanr.edu/2023WinterRoseCare
Workshop: Join UC Master Gardeners of Napa County for a workshop on “Garden - Garden Ergonomics: Using the Right Tool the Right Way,” on Saturday,
January 28, from 10 am to noon, at Las Flores Community Center,4300 Linda Vista Avenue, Napa. Learn proper body mechanics and how to avoid common gardening habits or activities that are risk factories for injury.
Help Desk: The Master Gardener Help Desk is available to answer your garden questions on Mondays and Fridays from 10 a.m. until 1 p.m. Send your questions to mastergardeners@countyofnapa.org. Include your name, address, phone number and a brief description of the problem. For best results, attach a photo of the plant. You may also leave a voicemail message with the same information at 707-253-4143.