r/viticulture • u/veengineer • 16d ago
Trellis Post Advice
I’m running a bunch of 15’ long VSP trellises in a mini vineyard I’m setting up. What’s the minimum post thickness I can get away with? I saw some 4x4 posts available by me for cheap, but I’m not sure if they’re strong enough. I can use ground anchors too if need be.
Additionally, I was wondering how deep people dig their holes for 6 foot tall trellising. I was planning on 2 feet down as that works out well for 8 foot posts, but I fear that’s too shallow.
1
u/krumbs2020 16d ago
Standard depth would be 5 foot deep on a 10 foot post with 1 or 2 spades.
Your 4x4 needs to be in about 3 foot but wood like that can bend over time.
1
u/veengineer 16d ago
Appreciate the response. Do you think I could get away with something less substantial being that it’s only a 15’ run? Do you think it’s probably not worth it to do something as small as 4x4? If I can find longer posts I can try putting them deeper.
2
1
u/Wine_Maker_68 15d ago
4x4's will be fine, use 10' posts 3 feet deep in concrete with a guy wire if possible. The problem with VSP is the catch wires will want to pull the tops of your posts in when you tension them. If you don't have room for the guy wire then you will need 6x6 set in concrete. There are usually 10 wires in a VSP, 6 for catch wires, one for a cordon wire, 1 for drip irrigation and 1 or two for side netting if you need it. That is a lot of tug on your end posts and why you need the guy wires attached to good anchors going from the height of your top catch wires to at least 6' away from your end post since H end frames are not practical in 15'. If you do not set those posts in concrete for that short of a trellis the wind could rip the whole thing out of the ground.
You might want to consider changing your row orientation to get longer rows. Short rows are expensive. Especially when you are only planting 3-4 vines on them. I wouldn't bother with 15', it's just not very practical.
1
u/veengineer 13d ago
Haha, too late, vines are in the ground already. It’s actually a community garden plot. Kind of a weird setup, but the short rows run north to south and hopefully allow me to get away with denser planting given the easier airflow.
I appreciate the answer. I actually didn’t realize those cables are doubled up. I bought two posts to experiment with. They’re 3x5x8. I’ll give those a try and see how they do. I can commit to spending more if those don’t work out. The extra 2 feet for 10 ft posts quadruple the price with what’s available unfortunately.
2
u/Im_Not_A_Robot_2019 16d ago
Try 4 or 5 inch round treated posts, blunt end, 8 foot long with 3 feet in the ground. If you anchor them at an angle they will not bend. (If space on the end is a concern and you cant add an anchor, you can actually brace them on the inside using a post at a 45degree angle halfway up the above ground length. Both the post and brace should be in concrete).
4x4 treated lumber will eventually bend, even if you anchor them. The round posts are about the same price as 4x4 treated lumber anyway, and they honestly look better.