If you are interested in growing kiwi, grapes, or another large vine, you will need a sturdy trellis. When growing a fruiting crop you need a trellis strong enough to hold not only the weight of the vine, but also the weight of the fruit. Having a properly constructed, sturdy trellis is the key harvesting good quality fruit. It prevents damage if the trellis were to collapse, makes pruning easy, and keeps your yard looking attractive. Today we are going to look at how to build a T-trellis.
The T-trellis we will be constructing in this tutorial is going to be used for kiwi vines. However, if you wish to grow grapes in the Geneva double curtain style, a slightly modified version of this type of trellis is what you will need. Plus, you don’t need to limit yourself to kiwi or grapes. This trellis will work to support any large vine you wish to grow!
We chose to make the T-trellis mainly out of landscape timbers. Landscape timbers are inexpensive, easily acquired, and we know that they hold up well in our dry sandy soil. You could also use pressure treated 4×4’s, wooden fence posts, or other materials locally available to you. The important thing is to follow the principles for creating a sturdy trellis.
Step 1: planning and acquiring supplies
The first thing you will need to do is figure out where to place the trellis, and how large you need your trellis to be. Once you have determined the size you wish to make your trellis, you can count the required materials.
You will need a line post at least every 30 feet. You will also need a larger sturdy end post, and 2 more posts for each end to make the braces. So for example, if you want to make a 60’ long trellis you will need 2 large end posts and 5 other posts. Placement will be: 1 End post, 2 brace posts, 1 line post, 2 brace posts, 1 end post. Each of these posts needs to be at least 8-9′ long.
You will also need to acquire boards to use to make the top of the T.
For our trellis we are using 8’ long landscape timbers. Since it is so wide, we are also using 2×4 braces. For kiwi, the trellis should be at least 6’ wide. If you are making a trellis for grapevines the trellis does no need to be quite as wide, and you can likely skip the braces. Whatever materials you use to make the top of your trellis needs to be sturdy enough to not sag or break under the weight of the vines.
You will need 1 cross piece and 2 braces for each line post. You will also need one for each of your first brace posts. So for our 60’ trellis example, you will need 3 cross pieces and 6 2×4 braces.
Then you will need 12.5 gauge high tensile wire to run between your posts. For kiwi you should run 5 wires. If you are making a grape trellis 2 wires should be sufficient.
Additional tools and materials you will need include:
- A spinning jenny to hold the wire
- High tensile fence wire cutting and crimp tool
- Crimps for high tensile wire
- Fence staples
- 1 strainer for each brace, and 1 for each trellis wire
- 2 brace pins for each brace (length will depend on the diameter of your poles)
- The tool for tightening strainers
- Large lag bolts for attaching your crosspieces to the posts
- Drill and drill bits for lag bolts
- Auger drill bit long enough to drill through your posts that is the same size as your brace pins
- Hammer
- Shovel
Before we head to the next steps, if you are unfamiliar with any of these tools or how to safely work with high tensile wire, please take a few minutes to refer back to our post on How To Build A High Tensile Fence for more information.
Step 2: placing your posts
The first thing you need to do to start constructing your trellis is to install your posts. To do this you will need to install your end posts first. End posts should be installed so that about 5’ is left sticking out of the ground. They should be buried at least 3’ deep, and should also be angled so that they are leaning slightly away from your trellis so that when you tighten the brace they are not leaning in.
Once your end posts are installed, run a string line between them. Then you can install your brace posts and your line posts. These posts should be buried at least 2′ deep, and should stick out of the ground about 6′. The brace post needs to be installed as close to but not more than 8’ from your end post, so that the 3rd post held horizontally will fit snugly between them. Line posts should be installed every 30’ or less.
Step 3: creating your braces
Once your posts are set, you can construct your braces. We are making what is called an H brace for this tutorial. It is the same brace you see used in high tensile fences. To help you picture what we are making, true to it’s name, it looks like the letter H.
First, you need to drill a hole in the center of each end of your 3rd brace posts, and also a hole through your fence post about a foot from the top. The H portion of the brace should be at least ¾ of the way up your end post, but no closer than 6” from the top.
Once you have drilled your holes, pound a brace pin through your end post until it is just sticking out the other side. Line up the hole in the horizontal brace post and pound the pin into the horizontal post until it is halfway in the corner post and halfway in the horizontal post.
Repeat the process with the other end with one small change. Do not pound this brace pin all the way in. Rather leave it sticking out approximate 1 inch. Once you have finished this step, you should have two vertical posts with a horizontal post wedged between them.
At this point your brace is almost complete.
Pound a fence staple half way into the back, bottom side of your end post and run a piece of high tensile wire through it. Loop the wire up and over the tip of the brace pin you left sticking out. Cut a loop of wire that fully encircles the 2 posts with about a foot of overlap. Put an inline strainer on the wire loop and use two crimps to hook the wire ends together.
The last step is to tighten the strainer until the brace is pulled tight. Make sure that the wire stays looped over the brace pin as you tighten your brace. You do not need to over tighten the wire. Just make sure everything is pulled tight. At this point you can pound the staple on the bottom of your end post in most of the way, but make sure that the wire can still freely slide underneath it.
*Important note:
The high end of the brace wire MUST be on the side your trellis will be pulling towards. The trellis wires will be pulling on the top of your end post, and the top of your brace post. So the brace wire MUST be pulling on the TOP of your brace post in the OPPOSITE direction as the trellis. It must also be pulling on the BOTTOM of your end post to counter the wires pull on the top of the end post.
The direction that you loop your wire on your brace is very important. Don’t construct your brace backwards! If you loop the wire backwards, the brace will not be nearly as strong because it will be pulling the same direction as your trellis wires.
Step 4: install your cross pieces and braces.
Using large lag bolts, bolt your cross pieces to your vertical posts. It is important to pre-drill holes for the lag bolts using a drill bit slightly smaller than the bolt. Doing so will prevent the boards from splitting as you screw in the lag bolts. Depending on what materials you are using, you can either bolt them to the sides of your vertical posts, or the tops.
Using our landscape timbers in this project, we opted to install them on top of the posts. Once the cross pieces were installed we installed braces. The braces consisted of 2’ sections of 2×4. They are attached diagonally with shorter lag bolts, one on each side of the post. The braces will make the trellis stronger and will help support the weight of the vines, particularly if the weight is not evenly distributed.
Step 5: install your trellis wires
Once you have your braces and cross pieces constructed, you are ready to install your top wires. The first thing you will need to do is pound fence staples partially into your brace post cross pieces in the locations you would like the wires. Next you will run the wire through the staples, across the top of the trellis and to the opposite end post.
Make a loop of high tensile wire around your end posts, secure the wires together with 2 crimps and staple it onto the post. Go back to the other end of the trellis to cut the wire and finish that end. Loop the wire around the end post and cut it with enough overlap to crimp it together. Before you crimp the second end, slip a strainer onto the wire. Crimp your crimps and staple the loop to the end post. Tighten the wire with the strainer just enough to take out the slack.
Now you need to go through and staple the wire to each of your cross pieces. Do not pound the staples all the way in. When you are putting in the staples, keep in mind that the wire needs to be able to slide freely under them.
Repeat this process for all of your other wires.
Once all your wires have been installed, you can tighten them until they have a bit of tension on them. You do not need to over tighten high tensile wire. Over tightening the wire can be dangerous as it can cause the wire to break. In the future, you can go back through and adjust the wire tension as needed using the strainer.
That’s it! Your trellis is complete. At this point you should have a sturdy new trellis that will reliably support your plants and their fruit crop for many years to come. Later this year, we will be writing an article on how to prune and train your kiwi to your new trellis.
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