Staining wood question

[McKinneyMike]

Paint needs something "toothy" to adhere to if you want good adhesion. It may not be an absolute requirement, but I have always used it on fresh wood surface before painting.

 

[FL-chick]

Do I need to use a primer if I sand it first?

 

[yogifink]

Yes you need a primer if you sand first.

And the home epot guy might not be wrong. there are quite a few exterior grade paints that have a primer base.