Most NG hybrids are designed to stay compact. If they winter (which I'm sure they will) they well grow out more. NGs are perennials but mostly grown as an annual in most zones. I would guess they would get a couple of feet tall and as wide. If your temps are pretty constant they should be fine they may like more shade but if they are doing well in that spot than it should be fine. Who knows they may even set seed for you. You may have to replace them in a couple of years but they are easy from cuttings.

Thank you for the information, I was wondering the very same thing. I bought a pink flowered one and it is gorgeous. I would love to have many of these around without having to purchase them. If you have any other suggestions on these send it my way.
Thanks,
Engi

I am excited to report that my 3 imaptiens that I mentioned buying earlier are doing well. I pinched them back and Stuck the pinched off parts in the soil. Some of the ones that I stuck in the soil are doing wonderful and have rooted. Now my mother plants are also looking much healthier and happier.
Engi

My new guinea impatiens are long gone now but my double flowered variety (I guess its wallerians) are doing well and have survived the hottest of days. They do root readily when pinched back...Can't wait until they start blooming again..

My NG Impatiens are still small, and have times of on and off blooming. I will never get them again because they wilt and have become fried and look horrible every day, even with daily watering. They aren't the best choice for areas with hot summers.

Chitown

Chitown
I have a few NG Impatiens and my temps get into the 100's with dry air and are doing fine. I am currently getting my second flush of flowers. To keep them from burning they need to be in the shade. Many Imps will stop flowering when temps get real hot but as the weather cools they start up again. One has to remember Imps are high mountain plants that grow in cool summer areas in the tropics, so many species dont like the heat. this is why more species are not found in cultivation.

Here is a picture of my NG impatiens today at 4pm. I watered them yesterday, and this morning, yet they still droop. They get a good deal of sun, but not full sun.

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Chitown

Chitown
They are getting to much sun. Plus the rocks make to much heat and the soil looks dry at least in the lower middle in front of the pink one. Being around 4 o'clock that is the hotest time. If you plant where they get moring sun that is cool they may do better for you.
It is a myth really that NGs like a lot of sun that is at least for most of the US. They may take more sun in their native habitat but the temps are much cooler, never reaching over 85f much. They are most happy with temps around 75-80f with high humidity.
Mine are in pot sitting on the ground and I water about every other day. The ground is never really drys out either.
My plants will often stop blooming when the temps get hot. That is why I go for the variegated types, they still give color when they are not blooming. I did have great success with the one variety by Pan American the plants never stopped blooming and the leaves kept the variegation. I was very pleased to say the least, sadly the plants had no name when I bought them.

MrImpatiens must be right, because my NG impatiens plants have bloomed non-stop and it's always warm and humid here in summer, but what I call warm, many of you in hotter climes would call cool.

I live in Bulgaria on the black sea coast and recently bought some NG Impatiens. In the summer the temperatures sometimes reach 95-100F, but because of the sea it is always humid. My impatiens get sun all morning, but in the afternoon it's shady. Will my NG impatiens be OK?