Monday, April 7, 2014

Problems affecting Impatiens

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.

Please check out my food blog - the latest post is Roasted Chicken Thighs with Potatoes.


HELENE said...

Hi Astrid, this is a problem over here too and production has stopped for a few years, so New Guinea Impatiens has totally taken over. It is an impatiens and looks lovely so not a bad alternative.
I like all the alternatives you mention, especially Heuchera, they now come with many lovely flowers too, so not only grown for their lovely leaf colour.

Jennifer said...

I haven't heard of this problem. Good to know! Most recently I have gone with begonias instead of impatiens. I like the leaves better. Given your warning about this problem, I think I'll stick with begonias.

Astrid said...

Hi Helene
Interesting that Europe has the same problem. It's great that there's quite a few substitutes to use.

Hi Jennifer
I hadn't either. A friend of mine from the Hort Society told me so I won't be wasting my money on impatiens this year. I attributed any die-off last year to the extreme heat and drought.

Patty said...

I heard about this problem a couple of years ago. Along with the boxwood blight. Some peoples go-to plants have to go elsewhere. I like your begonia alternative.

Indie said...

Oh my, I had no idea! It's been a few years since I've planted impatiens. That is too bad, as they are so pretty. You have some lovely alternatives, though!

Astrid said...

Hi Patty
I know! somehow this information slipped past me. Glad I know now. May garden will be full of begonias this year.

Hi Indie
I'm really disappointed too. I love impatiens but will have to make do with the other ideas. Gardening is expensive enough without throwing money away.

Nadezda said...

I love begonias as well, Astrid. I think the bright red spot in a shady place is wonderful. Perhaps this problem was here too because I could not buy impatience last spring and grew them from seeds. This spring I do not want to grow seedlings, decided to purchase impatience or better begonias in nursery.
Have a nice day!