Best time to plant

I just recently ripped out some bushes in the front of my house. I am going to have the stumps grinded down probably in the next week or so. I want to plant some small bushes or small trees in the area. What is the best time of the year to do it? Should I wait for the spring? Also, the area I want to plant them in is only about 15x15 and in the middle is a medium siz tree (20 feet tall). What kind of stuff should I avoid planting due to the lack of sunlight?

Thanks

 

20 ft is not a big tree. does the area get any sun?

 

Some but not alot. There is my "big" tree in the middle of the area. Around the area are bigger trees (100-125 feet)

 

First

What kind of tree???

 

I honestly don't know but need to find out. One of them is dripping sap onto my car and ruined the paint. What is the best way to determint the type of tree. If I posted a picture of the leaves from each one could you tell?

 

Yes

Post pictures please