For nearly 50 years, the garden impatiens (Impatiens walleriana) was the most popular annual on the planet. From the 1960s until about 2010, buoyed up by its ability to bloom abundantly in both sun and shade – even deep shade! –, to grow in just about all climates and to come in a wide range of colors and forms, it reigned supreme over our summer gardens and containers, pushing even the sacrosanct petunia into the corner.
Then in 2006, reports of a new disease that killed garden impatiens outright after a few weeks in the garden began to emerge. Called impatiens powdery mildew or IMP (Plasmopara obducens), it was apparently a new and highly virulent mutation of a disease already known to scientists. And it was inevitably fatal to I. walleriana and to several other impatiens species. By 2012, the disease had spread worldwide and by 2013, the impatiens market had crashed. Most greenhouse growers simply stopped growing it, no longer interested in incurring the wrath of disappointed customers.
Seed suppliers rushed in with replacements, notably hybrids between I. walleriana and the naturally resistant New Guinea impatiens (I.x hawkeri), claiming they were just as good, but gardeners weren’t fooled, or at least, weren’t fooled for long. The hybrids simply weren’t as tough and easy to grow as I. walleriana, nor did they perform at all well in the shade, in spite of what growers claimed, as I. walleriana used to do.
Ever since, gardeners have been hoping for the return of the garden impatiens (I. walleriana) in a disease-resistant form. And that may be happening right now. Read Are Impatiens About to Make a Comeback?