I recently found out that there are a number of very serious problems affecting the beloved shade-tolerant annual Impatiens. The 2 most serious are Downy Mildew and a virus called Impatiens Necrotic Spot Virus.
Impatiens Necrotic Spot Virus is not very well understood yet. It is believed to be caused by a small bug called a thrip (also called a thunderfly, storm bug, corn fly or corn lice). The thrip is a very tiny cigar-shaped insect with fringed wings.
The virus causes wilting, stem death, yellowing, poor flowering, sunken spots and/or ring spots on the leaves. But many times the plant dies without showing any symptoms at all.
Downy Mildew causes the same type of damage. Within several weeks of planting, a bout of humid or wet weather can cause perfectly healthy impatiens to suddenly lose all their flowers and leaves and be bare stalks overnight.
Many green houses in the USA have stopped growing and selling impatiens or at least have cut back by 75%.
Last summer this problem starting appearing more often in Canadian gardens.
This is a real shame. Impatiens have long been the most reliable colour annual for shady areas.
What now?
Well, no one is saying not to plant impatiens. The reports are just warning what could happen.
New Guinea Impatiens/Sunshine Impatiens do not succumb to this problem at all.
If you decide not to plant impatiens, here are some good alternatives:
Fibrous or wax begonias were my top performers last summer. Great for sun or shade.
Another wonderful substitute is Tuberous or Rex Begonia. These are gorgeous but quite a bit more expensive.
Coleus has made amazing strides these past years. They now come in a wide array of colours, textures and sizes. They perform best with a bit of shade or in full shade.
Caladium is an indoor plant but I have had much success with its gorgeous pink speckled leaves in shade containers.
Heuchera is another plant that has evolved a lot in the past years. It is a perennial, therefore will cost more up front, but it comes back year after year, so it will pay off in the long run. The reason I mention it as a replacement for impatiens is that it also comes in many multi-colours and stays lovely the whole summer.
Brunnera is another speckle leaf perennial that looks great all summer long.
Variegated Hosta can also add punch to a summer border. Not as much colour as impatiens, but a strong choice to replace the poor little sickly standard.
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