I would leave it as is. It will weather but not to the degree as a deck because it is vertical not flat.

Remember if you do stain or go with a solid stain (not paint) you will be doing it every 3 years to keep it looking new. That is very labour intensive as you must do both sides and get between each board.

Let it be, if you don't like it in a few years then clean it and stain it.

Not only that but pressure treated is treated with a liquid and you need to let it season and dry out before you attempt a solid color stain or paint as it will peel right off otherwise. I would vote for leaving it as well, and in my opinion pressure treated does not do very well as a fence in that it is usually southern yellow pine and the sun wreaks havoc with SYP in the sun (cupping, cracking, etc) especially on a fence as it usually just attached with crappy thin staples.

After 6 months use a good quality oil or alkyd based primer and a solid color stain from a quality mfr ?(Cabot, Olympic etc from a real paint store not a box store).

+1 Herb.

Cabot is good stuff.

Without a doubt, after proper seasoning, use a solid-body stain instead of a true film "paint".

Is a "solid body stain" the same as what Cabot lists as a solid stain? What about their semi-solid or even the semi-transparent types of stain they sell? I need to pressure watch or sand an older deck on a home I'm buying. It looks like it was built of pressure treated wood but never stained after that or even maintained much. It's very dirty thus needs sanding and/or pressure-washing before I treat it, but I'm not sure any nice wood-grain will become evident after cleaning it up...and thus I don't think a "semi-transparent" Cabot product would be the right choice. "Semi-solid" seems attractive to me...more rustic and less of a "painted" look as a solid Cabot stain would appear to be. TIA for any advice!

Semi Solid deck stain, I don't recommend solid or paint for a deck surface.

In my opinion one of the best ways to preserve a treated pine fence (especially posts that are buried) is with sump oil. Or you can use linseed oil. The people on one side of me did not want me to soak their posts in sump oil in order for it to soak into the timber. In fact they called me a nutcase for sugesting it would extend the life of them. For the record the posts are (hardwood) Australian redgum. Pailings are 13mm teated pine and the rails are 50x75mm treated pine. On the other side, where i have native bushland I did soak the base of the post in sump oil for just over 48 hours before putting them in the ground. I then sprayed the fence with sump oil. The untreated (much more wind protected) fence ended up with 4 posts snapped off at groung level they were rotten. There were pailings blown off etc etc. The fence on the other side off my home (which copped the FULL force of the wind is still nice and straight and still in good order. I still can't even wobble ANY post one bit. Both fences were put up together 17 years ago when we built. Another thing sump oil does is prevent termite attack. (If the buried part is soaked for 24-48 hrs before cementing them in). don't think that "treated" pine, or any other 'treated' timber will stop termites the chemicals leach out over time. Now the people next door want me to pay 1/2 for a new fence. I took them over showed them the other fence that was oiled and asked can you see any problem here. The grass is growing, as are all the plants there is no issues there. It's not as if i just poored oil all around the posts so the impact on the enviroment is infenticimal if at all. very little (if any) oil leaches out if they are soaked) the timber holds the oil inside it. If you don't want sump oil on your pailings then liseed oil is the next best thing. It is moisture that rots the timber(creates the enviroment for rottting) oils will repel the water keeping the as dry as posible and thus extending the life. And preventing yet more trees from being chopped down to cut into posts, rails and pailings. In fairness I said to those people next door if you buy all the materials I will help you put it up. But I am not paying 1/2 the cost for a fencing contractor to build another fence simply because you refused to take WELL KNOWN advice and called me a nut case in the process. Why should I fork out $2,864.00 (that's my half) simply because you chose not to listen to good old fashioned and well known advice. When I asked if he was prepared to pay half for the damage to my new garden bed, plants, shrubs and some other things I had stored where the fence fell on it all and brokes new shrubs etc he said "oh that's not my fault" "Can't you claim it on your insurance?" When asked why he isn't claiming his fence repairs on his insurance he said "Oh I don't have insurance". I said what happens if your house burns down how can you afford to pay the mortgage as well as the cost of living elsewhere. "Oh it won't burn down" was the answer I got. GO FIGURE.

Keep that in mind if I ever build a fence in Australia!!!!

I realize that someone is going to start slinging stones and boulders at me, but here is how I feel about your situation.

First, the attached is our deck. This photo was taken in July, 2012 and the deck stain/seal was in it's 3rd summer. I show it because 1) my railings are like a 'fence' and 2) this is PT pine that was sealed 'right out of the box'.

It is 'impossible' to honestly age the deck because it took me a year and a half to lay the boards - 3 screws every foot - clamped together instead of 'spacer'ed' and therefore some of the boards had been laid for a year or more before I sealed it.

You no longer need to wait any period of time prior to staining/sealing/etc PT.

The 'seal' I used is One Time (resin based) and this particular color is Golden Honey. When I 'reseal' it, probably next summer (2014), I will use Red Cedar, as the deeper the color, the more pigment, the longer the color 'lasts'. Resealing is going to be a matter of hosing it off - brushing any moss or other small areas (bird-do) that might need cleaned and then reapplying. No need to strip or pressure-wash or anything else. At the current time, water still beads up on it.

By the way, the surface area, including the railings is in excess of 3,200 sf and required approximately 10 gallons to do both side, including the underside and the posts.

My bottom line is that I would stay away from anything that would be considered a 'paint' that is going to cause you maintenance issues in the future. You may not care about that?

Just my .02 cents worth!