Very nice trellises. I think the single beam with the 8' spacing should be OK. It may depend as much on the characteristics of the 8' beam, as it does on the stress on it. Some lumber just has a tendency to warp.

I am wondering, does it really reduce the stress on the wire by placing the posts closer together? My gut feeling is that if the wire is freely moving through holes drilled in the posts, that the stress on the wire would depend only on the total weight on the wire, and not how many posts or their spacing.

But I could be wrong.

> I am wondering, does it really reduce the stress
> on the wire by placing the posts closer together?

It does not reduce the "stretch" force applied to the wire, which is definitely a concern. You're right, that is uniform throughout. But the weight load delivered by the enormous crop of berries (har-har) will be reduced by having more intermediate supports.

Nice job! They look nice, sturdy, etc. Being a berry fan, I always like seeing pics of other peoples' trellises

I like using the green vinyl coated wire because I try to make the hardware blend in with the plants as much as possible.

This spring, I'll be expanding my single galvanized iron pipe trellis by adding an additional 24' one.

My Chester's have 4 foot spacing between them, and that seems to work fine for me. I plan to use the same when I add my Triple Crown.

You may also want to think about adding the bird spikes. My birds just loved it up there!

Make sure to update this post in a couple years when you have tons of blackberries on there!
-Glenn

I'm also in Portland and am getting about 40 pounds of triple-crown fruit per 8 feet of row. Your trellis frame is plenty sturdy, triple crowns are largely self-supporting as far as fruit weight goes. Of course you want to tie them up else the whole plant would collapse. When your plants have been in 2 or 3 years, the protocanes should reach 8 feet by late july. After they are tall enough to tie off at the trellis top I would cut the top off immediately to encourage side-branching. Side branches can easily grow 15 feet.

You will have to do some climbing, though. Triple crown tends to angle its fruiting spurs at an upward angle; even the weight of the fruit does not usually bend them down below horizontal.

I have used the green-translucent coated steel wire for years and it weathers well.

Glenn, I like your iron trellis from the plumbing store. Hopefully, it will outlast treated lumber. But how did you fashion a closed square from threaded parts? You must have "cheated" somewhere.

Larry, how far apart are your Triple Crowns? I'm currently thinking 6 feet apart for mine. But I wonder if that's overkill. I'm planning the Kiowas to be 4 feet apart. But I'm just guessing.

I also got a bit worried and changed the top of my first trellis to have the complete "T" shaped top. When installing Wirevices it became clear to me how much tension would be on those wires. Although it also seems that 12-gauge wire is plenty thick and strong, when properly tensioned. I'll be using 12-gauge on the first trellis, and 9-gauge on the second. Time will tell and at least I'll learn something.

Hi Tcstoehr-
Yep. I cheated. :-) For doing a closed loop like that, you need to add something called a "Union" instead of a regular coupling. Below is a link to an example of one. Again, this makes for a pretty expensive trellis, but I like the fact that it's very strong, won't rot, and relatively unobtrusive when painted green. I'm sure yours will work fine for many years, and when you're done making the trellis, you'll have some money left over to buy the plants! (unlike me with my expensive trellis!)
-Glenn

Here is a link that might be useful: Iron Pipe Union

The triple crowns within the same row are spaced close as 2 feet. Many side-branches are trained to overlap; on occasion I have bundled 6 branches and run them down the row end, cutting them off 1 foot above ground. 4-foot spacing would be less jungle-like.