This year we’ll feature a lot of New Guinea impatiens (Impatiens hawkeri) out in the gardens. The photos in this blog show many varieties of this popular annual although our collection of New Guinea impatiens is based on seed grown offerings while all of these are obtained/purchased as plants (vegetatively propagated). However, these photos show you the exciting impact that these annuals can have in our full sun, part sun and shady gardens. Do check out our demonstration garden near the arboretum which consists of three beds that will showcase seed grown New Guinea impatiens that are available to the home gardener.
From 1999 through 2014, we had been planting close to 30,000 standard impatiens (Impatiens walleriana) in large drifts and throughout many shady locations out in the gardens. The photo directly below shows one of these areas filled with impatiens that were the workhorse of the part shade and shady garden. We had heard of Impatiens Downy Mildew (Plasmopara obducens) adversely affecting impatiens for a couple years prior to this and knew it hadn’t arrived in our area yet (or at least at the gardens). That all changed in 2014 when all of our Impatiens walleriana developed symptoms of this mildew and quickly degraded (see second and third photos below). Removal of these plants was immediately warranted. These photos were in mid summer and we had to remove, bag up and destroy all of this material, leaving empty spaces throughout the gardens. It was certainly traumatic and we went from planting 30,000 of these in 2014 to planting zero Impatiens walleriana over the past three years. We don’t anticipate going back to using these and have settled on the use of New Guinea impatiens alternatives as they are very mildew resistant.
New Guinea impatiens were first collected in 1884 (Papua New Guinea and the Solomon Islands) and introduced to Europe in 1886. This broadly defined species was later decimated in cultivation by a Begonia mite infestation and never regained popularity until they were “re-discovered” by a joint collecting trips facilitated by the USDA and Longwood Gardens to their native range. The first New Guinea impatiens hybrids were released in 1972 and the many selections of this annual continue to enjoy broader interest and increasing popularity everywhere. Preferring evenly moist, organically rich soils, there are a wide range of interesting flower colors and variegated foliage forms of this popular bedding annual. Well drained soils are essential and part shade seems to be ideal although shade is tolerable and some selections will tolerate full sun if provided adequate moisture. The vast majority of available selections out in the market are reproduced vegetatively necessitating the purchase of a plant. However, there are seed grown selections that we’ll feature at RBG this year.
Impatiens walleriana (pre July, 2014) at RBG
SunPatiens® Compact Lilac
SunPatiens® Compact Magenta
SunPatiens® Compact Electric Orange (above and below)
SunPatiens® Spreading Salmon Variegated (above and below)
SunPatiens® Spreading White Variegated
SunPatiens® Compact Tropical Rose
Painted Paradise Orange Improved
SunPatiens® Compact White & Compact Pink Blush (Ball Seed Trial Garden)
SunPatiens® Compact Electric Orange in a composition
SunPatiens® Series Collection at the Ball Seed Trial Garden (West Chicago, IL) (above and below)
Big Bounce™ Series trials (above and below)
Big Bounce™ Series
Big Bounce™ Lavender
Big Bounce™ White
Big Bounce™ Lilac
Big Bounce™ Series trials at RBG (above and below)
While we’ll miss the colorful tapestry of standard impatiens (Impatiens walleriana) seen above, it’s exciting to see all the new varieties of New Guinea impatiens (Impatiens hawkeri) coming out on the market. The trials below were at the Ball Seed Trial Garden (West Chicago) and show the exciting color range (including variegated foliage!) that is now being explored with these tough annuals! All of these are in full, blazing sun too (with adequate watering and good soil of course!).