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Impatiens Disease Spurs A Hunt For Shady Alternatives
by Susan Martin - posted 05/21/14


Sun Patiens® offers a similar look as bedding impatiens and are unaffected by downy mildew.1

Impatiens—for years they have been your go-to solution for providing brilliant color in the shade. Bedding impatiens is by far one of the most popular annuals for shade. Drive down a shady lane and you’re bound to see these colorful pink, red, salmon, purple and white annuals bordering beds and pathways.


Deadly downy mildew appears on the undersides of leaves of bedding impatiens (I. walleriana). If you see this, tear out the plants, roots and all, and replant with alternatives.2

This summer will be different. Sweeping borders of bedding impatiens will be a rare sight because of a new disease that has totally decimated crops of Impatiens walleriana. It’s called downy mildew (Plasmopara obducens) and currently there is no cure.

This disease quickly kills bedding impatiens, seemingly overnight. The symptoms of downy mildew include chlorotic or stippled leaves, leaves that curl downward, white downy-like growth on the undersides of affected leaves, premature leaf and flower drop and ultimately, total plant collapse. The disease may already be present on the plants you bring home from the nursery or it may develop once they are in your garden.

Impatiens May Not Be Available

Alternatives for Shade
 
Flowering Annuals
• SunPatiens® series and New Guinea impatiens
Begonias — seed types, Nonstop® series, Dragon Wing®
Wishbone flower (Torenia), such as Summer Wave® or Catalina®
Flowering tobacco (Nicotiana alata), such as Hummingbird Mix or Perfume series
Fuchsia, dwarf bedding and trailing types, such as Angel Earrings®
Mona Lavender (Plectranthus ‘Plepalia’) 

Interesting Foliage Alternatives
Coleus ColorBlaze® (Solenostemon  scutellarioides ‘Sedona’) or  Under the Sea® series
Caladium — wide variety of pink, red, white and variegated selections
Polka-dot plant (Hypoestes) — light pink, hot pink, red or white 

Other Colorful Alternatives
Rozanne cransbill (Geranium ‘Gerwat’), purple flowers from late spring into fall
Perennial coral bells (Heuchera spp.), wide range of foliage colors 
My Monet® (Weigela florida ‘Verweig’) and My Monet® (W. F. ‘Sunset’)
Tropicals, such as croton (Codiaeum variegatum), Canna, wandering Jew (Tradescantia pallida) and Dracaena

If you suspect your bedding impatiens have downy mildew, there is nothing you can do to treat them effectively. The best thing to do is  promptly remove the entire plants, roots and all, put them in a sealed bag and dispose of them in the trash. DO NOT COMPOST the diseased plants! The disease will persist in the soil, some experts say, for five years. Note the location where the plants were removed and do not plant impatiens there again, or they will likely be infected again. You’ll need to look for alternatives to impatiens for those areas.

As a result of the devastating effects of this disease, many growers and garden centers will not be offering bedding impatiens for sale this year. Those that do will likely be selling them with a disclaimer and will not replace plants that succumb to the disease. If you are one of millions of gardeners who plant impatiens every year, you’re going to need to look for alternatives.

Fortunately, there are many other options for adding color to the shady parts of your garden. Many are listed for you in the sidebar. Though some come close to offering the same look, you may need to rethink the design of your garden where you’ve always planted impatiens.

Impatiens Alternatives

For the most similar look to bedding impatiens, try planting SunPatiens® (Impatiens xhybrida). Fortunately, this beautiful species of impatiens has proven to be totally unaffected by downy mildew. Their flowers are a little larger than bedding impatiens and come in a similar range of colors. SunPatiens® are very easy to grow in sun or shade and will fill in a landscape quickly. Typically, fewer plants are needed to provide the same amount of coverage as bedding impatiens.

Begonias are the next closest alternative. Seed or waxleaf begonias (B. semperflorens) are also sold in flats at a similar cost, though their color range is limited to pink, red and white. Nonstop® tuberous begonias (B. xtuberhybrida) offer larger flowers in more diverse colors than the seed type and Dragon Wing® begonias (B. xhybrida) have a beautiful arching form.

The fantastic foliage of coleus (Solenostemon scutellarioides) can offer just as much color as bedding impatiens in an even wider range of hues. An extensive range of varieties is available with new introductions coming every year. Look for nonflowering or late-flowering types, such as the ColorBlaze® series. Once coleus blooms, it tends to go downhill, so those that don’t flower will deliver the best garden performance all season.


Copperleaf (Acalypha) has multicolored foliage that works well in shadier locations.3

Wishbone flower (Torenia) is an excellent, short bedding plant with a unique, true-blue color for the front of the border.4

Try Something New

Whichever alternative to impatiens you choose, be sure to read the labels and do your research to learn the individual plant’s cultural requirements. Every plant grows a little differently. It also might take some experimentation to find the best alternative for your particular landscape.

This season, turn a problem into an opportunity to try new things in your garden. You have a free pass to try something different! Who knows? You may just find some new plants you’ll like even better than impatiens.

PHOTO CREDITS:

1. Photo courtesy of Sakata Ornamentals
2. Photo courtesy of Purdue University
3. Photo courtesy of Proven Winners
4. Photo courtesy of Susan Martin

From State-by-State Gardnening May/June 2013.

 


Susan Martin is a lifelong gardener and the director of marketing for Walters Gardens in Zeeland.