I'm putting together a outdoor chair and the plans use pocket holes and pine,but I would like to use red cedar,is there anything different I should do?is pocket holes ok in cedar?
I would supplement the joints with glue and use coarse threaded Kreg screws.
Western Red Cedar is very soft. I've done a deck storage bench, an arbor and decking with 5/4 cedar, but none used pocket joinery. If you are using 5/4, the finished size is a full inch thick, be sure to use screws of the appropriate length and treatment.
I'm more wondering about splitting of the cedar as the screw goes in.
Cedar and pocket holes go together just fine. I've built a lot of outdoor projects using cedar and Kreg joints. Because cedar is soft and can be brittle, make sure you're not over-driving your screws. Try backing the clutch way down, to about a quarter of its max, and see if that drives them adequately. If not, up the clutch setting just a bit.
For outdoor projects, use our Blue-Kote or stainless screws. They're made for use outdoors and will hold up to the elements long-term much better than our standard zinc-plated screws. In any case, coarse-thread is the best choice. As Tim said, glue (exterior type, of course)is a good option--not so much to keep the joint together, but to help prevent the end-grain from wicking as much moisture.