After several difficult years, impatiens are back to their former glory

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As we begin to plan our garden colour for the upcoming season, it’s always nice to discover not only brand-new plant introductions but also improved varieties of popular, long-time garden favourites that can make a significant difference.

After several difficult years, impatiens are now back to their former glory. They have always been, by far, the No. 1 shade bedding plant, thanks to their generous spreading habit and stunning colour from late May until frost.

About seven years ago, when hot, humid August weather arrived, all the older, well-known varieties, like Super Elfin impatiens, suddenly contracted downy mildew and essentially died back almost overnight. This phenomenon started in Europe and spread worldwide. Most growers stopped growing them, but a few continued because consumers still wanted impatiens in their gardens, even if for a shorter period of enjoyment.

Both the Ball Horticultural Company, based in Chicago, and Syngenta, based in Switzerland, began the process of developing new varieties that had resistance to downy mildew. They went back to the original impatiens parentage to isolate the genes that had the ability to resist downy mildew. From this starting point, it was a long process of breeding this resistance into each of the colours. After three or four years of research, Ball released a series of ‘walleriana’ impatiens into the marketplace under the name ‘Beacon’. Syngenta took a little more time to ensure the stability and effectiveness of their new ‘walleriana’ impatiens, releasing their ‘Imara XDR’ series shortly thereafter.

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The ’Beacon’ series offers five colours and colour blends, while the ‘Imara’ series has nine colours in a nice mix. Both have been on the market just shy of two seasons, and each year more are being added.

Although both series have a high resistance to downy mildew, there is a slight possibility that, if they are planted near more susceptible, easily infected varieties, they too could be affected. With a fairly good colour selection in both series, it is no longer wise to plant the older, vulnerable varieties and risk disease transmission.

We have grown both new series for about 18 months and have not found any signs of downy mildew on either one. Once established, both series performed with the same vigour and beautiful habit that we expect from impatiens. Going forward, we will see more colours introduced until a full spectrum is available.

Double impatiens have been popular over the past few years, both as container plants and in hanging baskets, but unfortunately, even with some fungicide protection, they too have succumbed to downy mildew. It is best to avoid them until they are restored with resistance to this disease.

Since ‘walleriana’ impatiens were essentially off the market for a few years, folks turned to other alternatives, and New Guinea impatiens were the big winners. These heat-loving annuals do not have the same spreading habit, but their very large flowers, coming in a wide range of colours, and their green, bronze and variegated foliage create quite an impact. They do well in mass plantings and make

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ideal container plants, performing best in morning sun and with some shade in the afternoon heat. They do not like heavy shade or very hot sun. ‘SunPatiens’, however, have evolved as a heat and sun tolerant New Guinea and are very successful in moderately hot areas. Both are versatile and are not prone to downy mildew.

Because of their sun/shade tolerance, long blooming habit, attractive green or bronze foliage and their ability to play well with other plants, fibrous or wax begonias have also filled in nicely for impatiens. Low, medium and very large varieties are now available, and they are great used in containers. In mass plantings, fibrous begonias can make quite a statement.

This will be the first year that a broader colour selection of downy mildew resistant impatiens are widely available. They have always been the queen of shade annuals because of their easy care, pest resistance and long flowering habit in a wide range of garden situations. Both ‘Imara’ and ‘Beacon’ impatiens are now ready to add brilliant colour to shady containers and garden beds. Let’s welcome them back!