I recommend planting them 12" apart on center (e.g. meassured from the middle of one plant to the middle on the 2nd plant, the spacing should be 1 foot).

You can also plant them upto 18-24" on center, and that will give lower growing and more compact plants later in the season.

I do not recommend planting them too close. Whenever, we have planted them closer than 1 foot (6" or 8" on center) they have become tall, poorly flowering and generally not very attractive.

What you can do, is to plant two rows (one behind the other) staggered (see diagram below). You would need about 11 plants to fill in your 6' run. That gives a very nice look.

-x---x---x---x---x---x---x--
---x---x---x---x---x---x---x

Make the distance between the rows 12 x 0.886 = 10.5 inches. That will provide the best possible look for your impatiens.

e.g. between each plant: 12" on center (from middle of one plant to middle of another plant).
between each row: 12 x 0.886 = 10.5" spacing of rows.

Thanks so much for the info. I think I'm going to stick with the single row because the width of my boarder is only about 6-7". I live in a co-op development and the area for gardening isn't very large. But thought impatiens along the pathway coming into the house would look great. Since I'm sick and sit outside when I can I'll really be able to enjoy the beauty. Thanks again.

A single row is just as fine. Good luck and happy gardening.