I am not really an expert in this since DH usually takes care of the woodwork, but I think it depends on how much you want to space those posts away from each other and what will grow on them.

Carol, the posts that form my 'Arcade' are pressure-treated 6 x 6's, 9' high, spaced 6' apart.

{{gwi:247406}}

Hope this helps.
Connie

Connie, your arcade is beautiful! But I phoned around just now, and found a source of cedar posts 12' long, and my fence-person can put them 3' into the ground and cut off 1' at the top and have a row of 8-footers. I wish I could use PT lumber here but the roses will be right behind the vegetables and strawberries. So I guess I answered my own question. What was available up here and in stock, at an RI cedar lumber co., is 5" diam. round posts. So the garden will look sort of rustic, which is OK. Welded-wire fencing 4 ft. high, tomato plants between the roses. I'm looking forward to seeing your rose garden and nursery in person when I visit in early June to pick up my ordered roses.

Carol

Mine are 4 by 4. They are scaring me cause it seems the wood is spliting vertically down the posts. BUT on a positive note, a huge oak tree fell ON my trellis and the only damage done was to the cattle panel, which can be easily bent back in shape.

The round posts will be fabulous! One of my main problems with training roses to my pillars is that I have to be really careful not to crease the canes as I wrap them around the square corners of the posts.

cweathersby, the vertical splits (if I'm picturing it correctly) is called 'checking', and it's a weathering situation. This shouldn't affect the structural integrity of your posts at all.

HTH,
Connie

We finished our arbor/arcade this weekend with 4x6 posts at 8 feet tall, spaced 7-1/2 feet apart, buried 3 feet. Arbor is 8 feet wide, 30 feet long.

I wish I had been able to source the round posts in suitable diameter and height also. Lucky you!!

Connie, if you don't mind, what roses do you have planted on your arcade? I should be looking at ramblers, shouldn't I?

Oh, and is your arcade stained and sealed or just sealed? Aethestics, you know ;-)

Marcy

The wood on my arcade is left to weather ... I like when the wood begins to silver, and I don't want the work of stain or sealer.

Left to right, the roses are:

Pink Perpetue
Sombruiel
Rhode Island Red
Isabella Skinner (moving)
Heidelberg
Swan Lake
Parade
Pink Pillar
White Cap
Compassion

I intentionally went for climbers that I thought would be well suited for the regimented pillar style. Most of them are a little stiff, but they do the job if I don't let the cane get too rigid before I start training it. Isabella Skinner is moving because she produces WAY too many basals and is a big fountaining pom pom of a shrub. She needs to go to a location where this is desirable ... that's NOT a pillar. I'm assessing possible replacements from the pot ghetto.

HTH,
Connie

Gorgeous arcade! I can't wait to see it when the roses cover it! (almost seems a shame to cover some of the lovely structures I've seen people build and post pictures of on here!)

I seem to be getting more and more into "vertical" rosing (my own word) and am enjoying experimenting with different stuff. The training of canes is a bit of a pain but I'm actually enjoying it so far.

Lynn

I use redwood, for anything that's outside. Is that just a California thing?

I use redwood, for anything that's outside. Is that just a California thing?

Yes. Wood, like mulch, is a local thing, because the big cost is the shipping.

The arcade is beautiful. It made me sigh, out loud. (SOL)

The problem with all of this is...reality bites. Vertical checking increases the surface area exposed to weathering. Most treated lumber comes with a warning that should be read because it doesn't guarantee longevity; for that reason choice of lumber type is extremely important. In my part of the world, cedar lasts longer (and clogs saws). Osage Orange is also excellent (which explains why it's so hard to find...heavily taken for fence posts and nowadays some folks don't like the fall fruit.)

If you have any control over your wood, make sure to choose logs cut from the center of the free with no sapwood. Fewer knot holes is better although the 'knots' will out last the other wood, but by then, hopefully, the structure will be covered with roses.

And finally...how you set the wood in the ground is a major deal breaker. In some areas, wood in the ground rots. In some areas, what works in well draining sand doesn't in clay in the next yard. In some other areas, wood in cement in the ground rots. This is another of those instances where local knowledge is a necessity.

the thickness of the wood is fine but what is more important is anchoring it into the ground. It needs to be sunk at least 60 - 75cm in a hole filled with some hardcore and a sand/cement mix. You can buy ready mox posthole stuff but this is expensive so buy sharp sand and cement and mix at a ratio of 5 sand to 1 cement. Do NOT use metposts or any other fixing gadget - they will not work. We have worked as fencers and although timber in the soil can be at risk of rotting, if you use tanalised timber or a good preservative, the posts should be OK for 30 years.