Getting Wired!
ed. note. I have come to know Don Eastman as a highly honourable individual whose strong opinions are well-thought out and whose advice I respect highly. He also does a damn fine job of growing grapes, and lucky is the amateur winemaker on his selling list... Please look at his website and be sure to visit his vineyard diary pages. lfw
Most people don't think about posts and wire when they think about vineyards. A good trellis system will cost you at least as much as the vines that you put in the ground. Knowing how to install and maintain a good trellis system is an overlooked skill. I know from painful personal experience that ill advised decisions, sloppiness and neglect will come back to bite you in the rear end. The following will provide you with some of the things that I have learned along the way about posts and wire, and how to put them together. There are other ways of doing things, but this is what works for me.
Training systems:
My preference for vinifera varieties is a VSP (vertical shoot position) system. This has a low fruiting zone and then uses catch wires to hold the foliage in a relatively thin vertical curtain above. If you are spur pruning, you require a single load bearing wire to support the arms (and fruit). If you cane prune, I prefer two load bearing wires with a separation of 8-10" (shallow pendel-bogen). Canes are bent over the upper wire and tied to the lower wire. This means that most canes can be tied with one fastener and without twisting them around a support wire. VSP then requires catch wires to keep the foliage above the fruiting zone. I use 4 alternating catch wires starting about 12 " above the upper load wire with the first wire on the lee-ward side. Trellis height will depend in part on vine vigour, but I like to have the top wire at 6' or slightly higher, which permits a canopy that can grow about a foot above that wire before it starts to fall over. Many people use two or even three sets of parallel catch wires. This may look a bit neater, but it is a lot more work getting the shoots tucked in between the wires.
A variation of VSP is Scott-Henry, which uses a higher fruiting zone with two load wires and then trains half of the canopy up between catch wires, and the other half down between catch wires. Scott-Henry is something to consider if you suffer from excessive vigour, but otherwise an unnecessary complication.
An alternative to VSP is 4-cane Kniffin. It uses two load bearing wires, one about 3' high and the other at about 5' or slightly more. There are no catch wires. Vines are trained to have a main trunk to the height of the second wire and are then annually pruned to 4 canes, one cane in each direction for each wire. Canes either have to be twisted around the wires, or use two ties per cane. The Kniffin system uses less wire, but it normally takes another year to get vines trained up into the Kniffin system compared to VSP. Also, quality management is more straightforward with VSP. It is easier to identify crop load and thin if necessary. Fruit exposure is essentially impossible with Kniffin. Despite those limitations it can produce good quality Chardonnay and Cab Franc. Having said that, I am in the process of changing my remaining Kniffin trained Chardonnay and Cab Franc over to VSP in order to move the quality up another notch. (another 600 post extensions, and about 10 miles of wire!)
Equipment/tools:
Post-hole auger for installing wood end posts. 3 pt hitch with 12" bit is best, particularly if your neighbour has one. Hand-held power rental units are ok if you only have a few posts to install. If you have lots to do, either rent, borrow or buy a tractor mounted model. 12" width gives you enough room to clean out the bottom of the hole with a shovel and also provides a good angle for the end posts.
Post driver for steel posts. Basically, a piece of pipe plugged and weighted at one end. Can be purchased, or you can make your own. If you are doing a lot, tractor mounted post drivers are available. This is a two person operation, with one person to hold the post in position while the other operates the side-mounted post pounder (essentially a small pile driver).
Cordless drill with a good quality 8" long ¼" wood bit (the one with a sharp screw on the end, not the spade type).
Wire carousel. A lazy-susan type of apparatus that takes a roll of wire and spins as you pull it off the reel. You can hand-roll wire down the rows, but it is a lot easier with a carousel. It can be placed at the end of the row while somebody pulls the wire down the row. This normally requires two people, one to pull the wire, and the other to watch the carousel and undo any snags. I prefer to bolt it to a trailer and then simply drive down the row (after fastening the wire end to the end post!).
5' chisel end pry bar. Useful for loosening up hard-pan when you are drilling for posts, removing rocks from the holes, and for twisting in the end-post anchors.
Wire pliers - 2 pair heavy duty. One of the type that includes the hammer-head/staple puller, and one blunt nose with side cutters, and a gripping surface on the hand side of the pivot as well as in the nose.
A piece of ½ " pipe about 2' long for tightening wires.
Bolt cutters - 18". These are optional, but it is a heck of a lot easier cutting 9 gauge wire with short handled bolt cutters than using the wire pliers.
Materials:
End posts. I prefer 6" cedar for end posts and then apply a 12" collar of wood preservative for the area that is just above and below the ground. This is the section that is most vulnerable to rot. Pressure treated posts are quite brittle. It doesn't take much of a touch with a piece of equipment to break them.
Line posts. Steel lasts better than wood and is easier to install and maintain. For length, think in terms of your trellis height and add 30". If you don't get your posts in that deep they will gradually be ejected by the winter frosts (applies both for steel and wood). ½" a year doesn't sound like much, but after 10 years, your trellis system may look a lot different than you intended it to. Periodically going through in the spring with a sledge hammer to drive posts back down to the desired height is an avoidable nuisance.
Anchors. Standard vineyard anchors are the screw-in type, 37" long with a 4" wide auger type bottom. They come with either ½ inch or 5/8 inch thick shafts. Thicker shaft is better if you are installing in stony soil or heavy clay, particularly if it is summer and the clay has baked up to concrete consistency.
Wire. 9 gauge galvanized for load and anchor wires, and 12 gauge galvanized for catch wires. High tensile wire is an alternative, but it is a lot harder to work with. 12 gauge high tensile is about the same strength as 9 gauge regular and is cheaper per foot, but I suspect that the thinner diameter will leave it more vulnerable to corrosion over the years. (If anybody wants some, I have several rolls of 9 gauge crimped). Major problem with wire isn't breakage from load/stretch, but from corrosion after 15-20 years (and the occasional mishap with power pruners). Wire is available in 50 and 300 pound rolls (have recently seen some at 100 pounds). The bigger the roll, the less splicing you will have to do. But unless you have heavy duty equipment and lifting capability, it is a lot easier working with 50 pound rolls and putting in a couple of extra splices. A 50 pound roll of 9 gauge is about 900 feet, 50 pounds of 12 gauge is 1700 feet.
Wire splices. There is a product available called "gripple" which is relatively expensive, but very easy to use. These come in different sizes for the 9 and 12 gauge wire. If you are doing a lot of splices, a good alternative is splicing collars, but the crimping tool to use them is about a $100. You can sometimes arrange to borrow the tool from your local supply store. Most of the time, I do a manual splice using both sets of pliers. Do a right angle bend about 2" in from the end of both lengths of wire that you want to splice. Hold the wires parallel and overlap the two ends of the wires so that the straight sections can be held in the inner jaws of the blunt nose pliers with the two bent legs on either side of the jaws. Use the other pair of pliers to twist the wire around the straight length of the opposite piece (don't bend the wire back on itself). Repeat for the other wire on the other side. Result is a good, strong splice at no cost. If you are doing a lot of them, 9 gauge is hard on the wrists.
Post clips. Those holes in the posts are not for stringing the wire through, but for holding the post clips that hold the wire. You can make your own out of 12 gauge wire, but unless you have a lot of time on your hands, it is a lot easier to buy them pre-cut and pre-formed.
Staples. If you are following my advice on using only steel for line posts, then you only need 1 staple for each end post to hold the anchor wire in place. Always get the long staples. Short staples are false economy, particularly if you use wood for line posts.
Wire tighteners. These are ½ inch diameter short pieces of steel bar with a 45 degree bend, and a hole drilled through the longer section.
DON EASTMAN
www.littlefatwino.com