As others have mentioned, using the wood might not be the best for the wall.
Though if you space your vertical supports closer together you might get
better length out of it.

You also might want to put some 30# roofing felt between the dirt and the
wood for some added life.

Scott-
"cj" wrote in message
...
greetings, i need to build a small retaining wall and i am planning on
using 2x12 treated lumber. since the lumber will be in contact with dirt
should i paint it with a primer such as kilz or just let it be since it is
treated?
thanks cj