Over the years all the vines had to grow on was a handful of different posts haphazardly pounded in the Earth and some bits of wire. I figured it was time for an update.
3 - 6"x8"x12' posts
3 - 6"x6"x8' posts (for crosses)
Scrap sheet metal
1/2" Drill bit (for drilling holes for bolts and guide holes for training wire)
1/2'' All-thread or bolts +fistful of nuts, lock washers and flat washers
1/2"x10" Eye-bolts (for wire tensioners)
Scrap angle iron
Oxy-Torch/Plasma Cutter/Angle Grinder for cutting steel plate and all thread
Drill Post hole diggers
150' Heavy Fencing Wire (I used 10 gauge steel wire)
Step 1: Step 1: Clean-up the Area
Once I had the old posts and wire cleared out I aggressively pruned my vines. I removed a lot of the old growth and cleared out a huge pile of dead vines that were clogging the plants, preventing air circulation. Due to this there was a pretty good blight infestation. Hopefully by getting the old/dead out of the mix and getting the vines to grow up and out the improved circulation and exposure to sunlight will make for healthier plants.
Step 2: Plan Your Holes
You could go closer or wider. Determine the best course of action with what materials you have available.
So knowing that I was planning on placing posts every 8' I moved the first post about 2' away from the trunk of the first grape vine and marked the point with a stake. To the stake I tied the twine and pulled out about 20' in a straight line, making sure that it went directly over the trunks of the grape vines I wanted to trellis and tied it to another stake. Then I marked 8' and 16' from the first stake. I now had the points marked for my 3 posts.
Step 3: Dig a Hole Then Fill a Hole
So I dug down with my post hole diggers to about 48' in depth. Make sure when you're doing this you make sure that the holes you dig are nicely centered on the points you marked out and that you dig down as straight as possible. This will make leveling your posts up much easier. The reason for this is that any woody vine, as it grows, can put a lot of weight on a trellis. I wanted to have enough leverage in the ground to prevent sagging.
In to the holes I dumped some gravel. This helps to prevent your posts from rotting out. I like to put 6''-8'' of gravel down my holes. Once you dump the gravel in you drop your 6"x8"x12' posts down the holes and use the posts as a large tamping rod to pack the gravel down.
Face all your posts. Since I was using 6"x8"s I faced them so that the 8" face face was in, so when capped them with a 6"x6" they would form a 'T' with the arms outstretched.
Tack your scrap 2"x4"s on to the posts and level your posts. Check and recheck because you won't get get any mulligans after this point.
Mix your concrete. I went with 3 sacks per hole because again vines can get heavy.
Step 4: Cut Your Posts to Height
Not to worry. Remember you bought 12' long posts for a reason. Since we buried ~4' of them you now have ~8' sticking out of the ground.
Tie your twine from the top of the first post to the top of the last post and make sure you tie it tight. Determine a comfortable height that you would like the trellis to be. For me I chose 7'. Now again grab your level and get that twine to read level between the 3 posts at your desired height. Now mark a line on all three of your posts with your pencil on all 4 sides of the posts.
Break out the saw and cut off the excess. Now you have 3 posts that are of equal height.
Step 5: Cut Your Steel and Place 'T's (Optional)
Next I cut my 3 6"x6"s to 7' in length, marked the center (42"), centered a half-moon piece of steel under and over each one then tightly clamped the steel and wood together. By having the holes in the steel already predrilled I simply drilled through the pilot hole on one side, through the 6"x6" and out the pilot hole on the other side. I installed 4 1/2" bolts to hold it all together. Repeat the process for the other cross pieces.
Next take a cross piece and place it on top of your post. Use your hammer to persuade it in place if necessary. Ensure that the post and cross piece are mated together and that the cross is centered on the post. Again drill through the pilot hole on one side, through the 6"x8" and out the pilot hole on the other side. Bolt together and repeat the process for the other posts.
Now you've got three (or more lol) capital 'T's in your garden and it's time to add wire.
Step 6: Wire It All Up
As you can see I placed a wire every 12". Use your 1/2" drill bit and drill a hole through the center of the post at every point you've made. depending on your layout (did you install the cross pieces?), and the height of your posts your number of lines could vary.
If you placed cross pieces measure 12" and 24" from the center point and make a mark. Drill those holes too. Place an eye-bolt, facing in, and put a nut on the outside face of the post. Thread the nut on just a few turns. Now thread the wire through one eye bolt and wrap it over itself, through the center post and to the opposing eye bolt. Cut off the excess wire and wrap the tail end around this eye bolt. Make sure when you do this you pull the wire hand tight. Don't go nuts yet and try to get it crazy tight.
Measure the distance between your posts precisely and cut some chunks of angle iron ~ 6" long. Subtract the thickness of the angle iron x2 from the distance between your posts; this will be the length of the pipe you need to cut. Now weld the angle to either end of the pipe and slip it in between the posts. Don't overly concern yourself with it falling out.
If you chose to install the cross pieces place a angle&pipe piece on either side of your cross pieces.
Now you can go crazy and tighten those nuts that tighten the eye bolts. The wire will be pulled and cause the posts to slightly toe in. This pressure will prevent the pipe&angle brace from going anywhere and will prevent your vines from drooping once they start to put their full weight on the wires.
*Note: I used stainless eye bolts and nuts. In a few years when the wire stretches out it will be much easier to tighten than trying to work with @$^%^%$ rusty nuts and threads.
*Note: It isn't necessary to install the angle&pipe braces, but I find worry there is the possibility of the tight wire and wight of the vines pulling the posts out of level, which means that I would never really be able to keep the trellis wires tight and the vines could sag and be damaged. Maybe I'm paranoid and over complicated matters but after 3 winters the wires still pluck like guitar strings.
Step 7: Train Your Vines
I completed this project 3 years ago. I'll take some pictures of how my vines look once this season starts. But last year they produced grapes for the first time in over 15 years. I think that the vines were shocked when I pruned them and they took about a year to recover. The second year the two vines that are on this trellis grew vigorously and last summer they produced delicious grapes.
As far as wood to use, I'd suggest cedar, oak, osage orange, or locust as all are great against the elements. Don't use treated lumber around anything that produces food, there is always the threat of the chemicals leeching in to the food you ingest. Me, I have a couple hundred large teak timbers that will outlast my kids, so that's what I used lol.
Between the two plants that are on this one trellis I picked a 5 gallon bucket worth of grapes. I have another 3 vines that need to have a trellis made for them and they barely produce anything, so I would call the trellis a success. Since I installed the cross pieces the vines have sort of branched out like a tree and since I cut my posts off at 7' tall I can stand flat footed and easily pick the grapes that hang down.
*Note: Besides a great increase in yields I've also noticed that the overall health of the vines has improved and haven't seen the brown spots on the leaves, or vine rust. I contribute this to proper air circulation and sunlight reaching all parts of the plants. Time of course will tell as the vines further mature and spread. I have no training on grape cultivation, merely what I've read on the internet.
Anyways, I hope you enjoyed my Instructable. Now get out and go build something!