New Downy Mildew Resistant Impatiens Cultivars

Almost 10 years ago, northern gardeners witnessed an unusual disease attack classic garden impatiens, the best-selling shade-tolerant bedding plant. Infection caused the total collapse and, ultimately, death of plantings. It moved easily by wind and rain, and would lay dormant in garden soils, ready to infect the next year’s plantings. No chemical spray or change to cultural practices could keep impatiens downy mildew at bay. Gardeners had to abandon Impatiens walleriana—also known as busy lizzy or patience plant.

I am happy to report that it’s time to plant impatiens again.

Two series of Impatiens walleriana have recently been introduced that are highly downy mildew resistant.

Beacon^® Impatiens

 The first series to look for is the Beacon^® impatiens, developed by PanAmerican Seed. Years of painstaking breeding work in the Netherlands, followed by serious plant pathology work, has resulted in a series that is highly downy mildew resistant. There are six colors of Beacon: Bright Red, Violet Shades, Salmon, Coral, Orange and White. PanAm has also created two mixes from these colors. Beacon impatiens reach a mature height of 15 to 20 inches and spread 12 to 14 inches. PanAm recommends spacing in a mass planting at 8 to 10 inches apart. Plant Beacon when the chance of frost has passed in spring. If you want to start your plants from seed, a number of the larger mail-order catalogs are advertising Beacon seed for spring 2020.

 

These plants have been extensively tested the last few years, including in Minnesota. The University of Minnesota West Central Research and Outreach Center in Morris included Beacon impatiens in its annual plant trials in 2019. According to Steve Poppe, horticulture scientist at the center, Beacon^® Salmon was one of the “Top Ten Performing Annuals” of 2019, a high honor indeed.

Imara^™ XDR

Also available in 2020 is the Imara^™ XDR series from Syngenta Flowers. Fun fact: Imara is a Swahili word meaning “resilience.” XDR stands for “extra disease resistance.”

There are nine colors in the Imara^™ series, including Orange Star, Rose, White, Salmon Shades, Purple, Red, Orange, Pink and Red Star. They also have one mix. These impatiens are uniform in height and width at 10 to 12 inches. For best results, plant them after the last frost. Seeds are also available from the larger mail-order seed companies.

Imara^™ was tested extensively in both the United States and Europe including trials in 2017 and 2018 at Cornell University’s Long Island Horticultural Research and Extension Center in upstate New York.

From spring to fall, no bedding plant packs a flowering punch like garden impatiens. Whether you used it in hanging baskets on a north-facing front porch, in mixed containers with begonias and other shade lovers, or popped it into the garden between hostas or in large colorful beds, the blooming power of this top-selling annual was sorely missed.

Finally, because of hard work by some brilliant breeders who’ve developed downy mildew resistant impatiens, they are back!

This article by Debbie Lonnee appeared in the March/April 2020 issue of the Northern Gardener.