How to build strong trellis for veggie garden?

Question

Hi Team,

5 years ago I build a basic garden trellis using hardwood stakes and econony pine trellis. The main stakes buried in the ground have rotten away and I want to build something that's sturdier and can last longer.

The trellis is around 1.8m wide, 1m deep, 1.5m tall. It doesn't need to support much weight other than the vines that will grown on it.

My question is what type of timber should I use for the main structure? The posts are buried in soil so they have to be treated, but can't use CCA treated timber near edible plants. ACQ treated timber are only in sleeper shape and not posts.

Can I use untreated structural pine and paint an exterior protection, then coat the length that will be buried with inground timber protection?

Thanks!

Dave-1 · Answer

Good Morning @KevC

The Timber T posts where attached to the bottom raised garden bed board. This is where they eventually rotted (several years) The timber was recycled from someone throwing out their old raised garden beds btw so it had a long life overall.

The star posts I used later looked less impressive but still did their job.

With the vertical mesh that I had a concrete footing with a stirrup post supporting with crossbeams. I like this the most for longetivity and access.

The post holes were around 450-600mm deep (I have LOTS of rocks under the soil) With the star posts I would be sinking them in 500mm to support a trellis on its own, if you make up a square rigid frame for the top then you could get away with 400mm only.

Dave

MitchellMc · Answer

Hopefully @Dave-1 can let us know, @KevC. I suspect any post of that calibre would need to be concreted into the ground with a footer.

Mitchell

KevC · Answer

Thanks for the suggestion with the T posts. I think I'll use 5 of them as the ground stake, recycle the existing hardwood stakes to build the upper frame, and reuse the crosshatch.

My current trellis is not very rigid even when new, it can sway to the side or twist when I push it. I know that part of the reason is that I didn't bury the stakes deep enough, but also the diagonal supports weren't installed very well. The timber crosshatch is fairly flexible so doesn't provide structural support.

With the example builds you showed, how do you keep the T post upright, and the structure rigid?