It has now been over a year that gardeners from Florida to Maine and as far west as the Chicago and St Louis have struggled with the impatiens downy mildew disease. We know it is a water mold, carried by spores on the air, and causes devastating damage to one of the most popular bedding plants in the United States.
You may have read about it in the newspaper, seen it in gardening magazines or had you own shade beds affected last summer. It is a big problem, and may be for the next several years.
There is no cure- and nothing homeowners can do to reduce their risk. Professional growers have a few chemicals to prevent the disease, but they only last for six weeks at the longest.
We attended several grower meetings over the winter where the largest topic of conversation was downy mildew. Professional opinions vary as to what to do. Some say grow and sell impatiens and warn people that they may die- they are annuals and are just going to die in the fall anyway. Some are not growing them at all figuring they don’t want the liability.
While there are few things that match impatiens in ease and color range, there are other great plants for shade.
One of my favorite new plants is the begonia ‘Whopper’ series. Offered in both green or bronze foliage, and either redor pink flowers, they were a stand out at last summer’s Penn State field trial. Large flowers, and height and spread of up to 3 feet, this is one bodacious begonia.
A lesser-known plant is torenia, or wish-bone flower. Either spreading or upright, it comes in a range of colors from white, yellow, blue, pink and dark purple. Torenia does well in shade to partial sun areas.
Luckily New Guinea impatiens are not affected by downy mildew. Most people are familiar with the vegetative New Guineas. They have large flat flowers, and reach 2-3 feet in height. The ‘Divine’ series is grown from seed, and has slightly smaller stature and flowers. Sunpatiens, a form of New Guineas that do well in sunnier areas, are also a great choice. I would not put them in deep shade, however, as they will stretch.
Foliage plants offer many colorful options. Coleus gains in popularity each year, and thrives in the same situations as impatiens. The caladium bulbs produce colorful large elephant ear-shaped leaves. They naturalize in Florida, but need to be dug up in the fall if you want to keep them year to year in Southern PA.
My advice is stay away from impatiens from a year or two and see what this disease is going to do. When life hands you downy mildew, plant begonias or torenia.
In the northwest corner of Colerain Township, along Wesley Road, Lancaster County maintains a small county park named after a world class ornithologist born and reared in Lancaster. Ted Parker died in a plane crash in tropical South America while pursuing his study of tropical birds. To this day, his knowledge of tropical South American birds remains unchallenged.