Landscapers and gardeners in Maryland, Northern Virginia, and Washington D.C. are facing a new challenge this year. There has been an outbreak of an aggressive fungal disease that, at least for the short term, has virtually eliminated the planting of the extremely popular and useful shade-tolerant annual impatiens. The disease is called impatiens downy mildew. It manifests itself with reduced vigor, pale foliage, and inconspicuous mottling. As the disease progresses landscapes face stunted plant growth, wilting, and soon, extreme leaf drop. While it is technically possible to treat planting beds with fungicides and reduce the risk of the disease, treatment is not really practical in most settings, as impatiens downy mildew is so wide spread.
As a landscape design company in Montgomery County, Maryland, landscape maintenance is an important service to many of our best clients and enables us to continue to be involved in the evolution of their gardens. We have traditionally used impatiens to bring color and life into the shadier parts of a property. We have also planted them in a more “gardenesque” manner where they weave in and out of foliage perennials and shrubs throughout the garden to highlight other plantings and provide a subtle sense of rhythm.
Production of these wonderful flowers in their myriad of colors has almost ceased for the time being, forcing us to be creative in finding substitutions.
There are some obvious and very good replacement shade annuals, chief among them the Begonias, Coleus, Caladiums, and Torenia. While none of these flowers have quite the color intensity and density of the impatiens, they each have their own appeal and potential.
Another approach we take is to locate the seasonal colors in slightly brighter areas. For sunnier outdoor spaces we consider the following plants:
We also add shade loving perennials as a substitute for impatiens in low maintenance and sustainable gardens.
Good candidates include the following:
We are looking at impatiens downy mildew as a challenge and an opportunity to stretch and grow. For now, we are bidding a reluctant farewell to the indispensable color of impatiens. It seems likely that it will be years before horticulturists develop a new variety that is disease resistant. In the meantime, we are experimenting with a wide variety of wonderful alternative plantings.
If you are interested in incorporating a garden into your landscape design, check out some of our recent landscape and planting projects throughout Maryland, Virginia, and Washington, DC.