Question
QUESTION: I have 18 large flower pots/ containers that I plant each year with annuals. I have full sun almost all day. I love having New Guinea impatiens because they take off on their own, last a long time, need no dead-heading and other than water, seem to thrive.  Or at least used to.  Recently, they still do well in my large cement pots but don't do well in my smaller (plastic) pots ( about 2 1/2' in diameter. The leaves get semi-circular holes on the edge, then the flowers start to shrivel and die. If I take them out and put them into the ground, they recover. I usually plant Dracaena, ageratum, alyssum, vinca and dwarf petunias in the puts with the impatiens. I have changed all the soil and use new potting soil, I mix in some Osmacote fertilizer before planting, and buy seedlings from reputable nurseries. I would love to plant them again this year (last year I substituted geraniums in those pots), but I am afraid I will have the same thing occur.  Can you help?

ANSWER: Judith,
How are these pots getting watered and where are they located?  The symptoms you describe sound like a fungal problem and many leaf-spot fungi are caused by frequent moisture - splashing of the plants with a hose when watering or dripping from gutters or air conditioners over head perhaps?  The fact that the plants recover when you place them elsewhere argues for something cultural, that is, something that is physically happening to them in that location. If not water, perhaps the mixing of so many plants in the container causes poor circulation that leads to moisture on the NG leaves at night (dew) or even during the day.

You've done everything else right - new soil, time-release fertilizer etc.  Look at the location with a detective's eyes and see if you can find something that is causing the foliage on the NG's to be moist.  You could also try spraying the plants with Serenade, an organic fungicide that works by out-competing the "bad guys."  You'd start spraying as soon as you plant, and, of course, try not to get the foliage wet when you water the pots.

I hope this helps!
C.L.
www.gardenlady.com

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QUESTION:   Thanks for your prompt answer.
 What has always puzzled me is that I have been planting these same pots for 19 years, and had no problems with the N.G. impatiens until about 6 years ago. I water the pots with a garden hose fitted with a sprinkler head, like a gentle shower. If the weather is really hot and sunny, I water every day. Otherwise, only when the pots are dry.  There really is a lot of sun here, since I have a southern exposure.
 You may be correct about the fungal infection, but could it possible be an insect or a slug invasion?? Or, could you think of another easy-growing self tending annual that would do as well in those pots??

ANSWER: Judith,
Slugs would leave a slime trail - can't think of an insect that would leave spots on the edge... try planting one pot with the NG's as usual and don't let the leaves or flowers get wet when watering...no gentle shower, but only dirt-level watering and see if the symptoms go away. Otherwise, try Red Riding Hood Mandevilla Vine - short (not vining in summer) and no deadheading and very very showy, although a bit more expensive than NG's.

I hope this helps,
C.L.

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QUESTION: Thanks for the suggestions.  I hope I can find Red Riding Hood Mandevilla Vine at my usual nursery haunts when I start shopping.

Answer
You're welcome! (BTW, Sometimes this Mandevilla is referred to by its old name, Dipladenia, and you want to be sure to get Red Riding Hood or the white equivalent because the others such as Alice DuPont are large growing vines.
all the best,
C.L.

(no need to thank via a question because I have to respond to all questions asked, so I'd have to respond to your thank you.)