What type of posts should I use for my trellis?
Here I will give my opinions based on my experiences.
For the ten acre field that I planted myself, I used 6” pressure treated spruce round posts every 10 feet. This trellis system was definitely overkill. What I like about it, is that it looks amazing. Nothing looks better than wood posts in my opinion. It gives that natural look that everyone expects when going to see a vineyard. I have all wooden posts at the front section of the vineyard which is what customers see whenever they drive up to the property. When looking at the benefits of wooden posts, it is tough to find anything past appearance. They rot, so you will me eventually have to replace them. It is beneficial to have all rotten posts replaced before the growing season so this is yet another task that needs to be completed in the already busy spring. Of course there is the topic of staples or hooks. You will have to install staples everywhere you want to run wire. If you want to move that wire up 4 inches, unfortunately you have to install another staple. Staples fall out all the time as the post gets older and soft. The disadvantages of wooden posts are starting to pile up but, yet they are still my preference. I just like the look and feel of them.
I took over another 18 acre field and this field used a cast-iron posts. I do like this field as well, however since it isn’t customer facing production becomes much more important over appearance. One of the major areas that I like about this field over the wood posts is how narrow the posts are. It is much easier to get close to the vines with the tractor when I am trying to turn the top soil to keep the weeds off. The posts can’t be any more than an inch or two thick as compared to the 6 inch post I have in my wooden trellis. Normally you would only use 4” posts with a wooden trellis but, I decided to go with the more durable option. Either way, this is one major benefit of the metal posts that you can get much closer to the vine, when you are on the tractor, the trellis just gets in the way so the smaller it is, the better. They are also much easier to install wires as well, there are notches in place for where you can put your wire. Overall installation is much easier as well I find. The main disadvantage was always that they rust and look terrible. However, more and more trellises are being installed now with metal rust-free options.
For commercial options, I see the two major options right now being metal and wood. Like with everything though, other materials are continually being looked as costs and quality are important factors. As for choosing the right option for you. With everything, starting with cost is a good starting point. Cost is something that you are going to have to price out on your own by contacting suppliers. It is going to vary greatly on your location and prices fluctuate over time. Don’t get me started on how much the cost of wire has increased since I have started. Cost aside, hopefully my experiences with different posts helps you come to your decision.