K.N.
For what it's worth, pansies are usually planted early in the Spring (they prefer cooler weather). I've seen them in purple, white, yellow and orange. Impatiens are more of a summer flower that like shade. The colors I've used are white, orange, coral, red, magenta.
I'm sure if you Google either you'll get pictures & can determine which it is you like.
I've also used hosta around trees. They're a perrennial with long green or variegated leaves. They flower later in the summer and shoot out long stalks with smallish white flowers on them. They also like shade -- and grow like crazy over a couple of years. T