Mike Darcy
Head “plant nerd,” longtime speaker, host of gardening shows on radio and TV, and author of the In the Garden email newsletter.
You can reach Mike, or subscribe to his newsletter, at [email protected].
It probably goes without saying that it has been a long, hot summer and early fall. With record high temperatures and little or no rain, one might have expected customers to stay away from garden centers.
However, this was not the case. Customers continued to shop for plants and also relied heavily on garden centers for advice.
I always look forward to hearing what visitors to my garden are going to ask — and recently I asked employees of several garden centers what kind of questions received during this past summer season. The questions and comments listed below are not in any particular order except for the first one.
Is there such a thing as a kink-proof hose? From my own personal experience, I would say there is none. Or if there is, I and many other gardeners would like to know about it. During the past couple of years, I have purchased four different brands of garden hoses with a label stating that this hose is “kink proof.” None of them have passed the test.
Hose kink. Photo by Doug Barragar
Are compost and fertilizer the same thing? Many customers seem to think so, according to one garden center employee. Many times this summer, customers have brought in leaves — especially tomato leaves — that clearly show a lack of nitrogen. When advised that plants need nitrogen, customers often reply that they used compost at the time of planting. They are surprised to hear that fertilizer is needed to keep plants healthy.
Powdery mildew. Photo by Rich Baer
How can rose owners deal with powdery mildew and black spot? An additional question about black spot is: “I sprayed my roses to get rid of black spot, but the spots are still there. When will they go away?”
I asked past-president of the Portland Rose Society and avid rose grower, Rich Baer, for his comments. He said that black spot and powdery mildew are two of the most prevalent diseases on roses here in the Pacific Northwest.
Powdery mildew thrives in an environment with warm afternoons, cool evenings and high humidity. The spores germinate when the night-time temperature is cool and foliage is laden with dew or other moisture. Some rose growers have learned they can prevent powdery mildew by overhead watering in the late afternoon so the foliage is dry by evening.
Powdery mildew spores can become airborne and spread by wind. Black spot spores, by contrast, need to be in water for about eight hours in order to germinate. The spores are spread by rain and the disease spreads by splashing.
Black spot. Photo by Rich Baer
Once a leaf has black spot, that spot will not disappear. It is common for customers to go to a garden center with their rose leaves covered with black spot and then being concerned that the spot did not go away even though the leaves had been sprayed with a fungicide. The black spots are the result of dead leaf tissue and the leaf will eventually turn yellow and fall off.
Fungicide generally tends to act as a preventative measure and not a curative one. Once the tissue is dead, it is not going to come back to life!
How often do I need to water? That has been a common question this summer. It is difficult to answer without knowing details about the plant. Customers tend to want a specific answer and often there is not one. There are many factors involved: What is the soil like? Where is the plant growing? Is it planted in the sun when it should be in the shade? Are tree or shrub roots competing for moisture? Has compost or mulch been added?
On shrubs and trees, think about where the roots are. The plant is probably not getting adequate water if it is only being watered at the base. As the plant grows, the roots move out into the soil and perhaps a soaker hose under the drip line would be a good solution.
What if plants are in containers? That’s an entirely different set of circumstances. With the containers in my garden, I found that many needed to be watered once a day and sometimes twice. Customers need to be reminded that as the plant grows during the season, the roots are taking up more and more space from a confined area and thus they need additional water.
Lace bugs. Photo by Rich Baer
How do I deal with lace bugs? Having been off the radar for a couple of years, they began to make their ugly presence known on rhododendrons once again. This has provided garden centers an opportunity to not only suggest control measures but to inform customers that rhododendrons with indumentum tend to be resistant. In my own garden, I have several rhododendrons with indumentum that have been resistant to any lace bug damage in spite of being in close proximity to other rhododendrons without indumentum that have been heavily infested with lace bugs.
How can I get pollinator-friendly plants? There has been a huge increase in customers wanting them. With all the recent press about the many issues facing honeybees, gardeners want to help and not just the honeybees but many of our native bees as well. There is also much interest in those plants that will attract butterflies and many garden centers have special sections for pollinator-friendly plants and those that will attract butterflies.
Where can I get native plants? Gardeners have become very interested in native plants and many garden centers have sections for these as well. Native plants cover a very diverse group and some such as Mahonia and Arctostaphylos have become mainstream plants in local gardens. There are multiple benefits of planting the early-blooming Mahonia, as the flowers are a winter source of food for hummingbirds and honeybees. Later in the season, the berries are a favorite food of many birds.
I think that as this dry season is ending, we can look back and learn from some of the recent trends that have been occurring in the gardening community. I also believe that we have all gained much information on the tolerance of people and plants in the heat!
