Pruning Your Grapes After a Major Freeze

Previous posts, Pruning the Grapes (Part 1) and Pruning the Grapes (Part 2), have discussed techniques for pruning your grapes. In most cases, these two posts contain everything needed to prune your grapes using the four-cane Kniffin system. However, pruning grapes sometimes involves more than simply dressing them up. In general, your canes can remain fully productive for many years, but sometimes mother nature steps in and causes severe damage. In my case, all of my young caned died completely and there was nothing to do about it. In addition, two-thirds of the mature canes suffered above ground loss, which is what I want to talk about in this post.

Good hearty canes will come back after a major freeze that kills the top of the plant. No, you won’t get anything in the way of grapes after the top is killed off, but the root stock is well-established and coming back after the freeze is a lot faster and easier than planting new canes. The spring after the freeze will see the old canes looking like gray skeletons and you might think everything is lost, but give your plants time. Look carefully at the ground around the old canes.

The first year after a major freeze will see all sorts of suckers coming out of the ground. Just leave them be. Let them climb up using the old canes as support. What you’ll end up with with look like a horrid mess. The new canes will grow everywhere. That’s fine, just don’t look too often if the mess offends you.

In the spring of the second year, carefully work with the mess. Remove the skinny trunks. One or two the trunks (with their associated canes) will look quite hearty. Leave both for the time being. Also remove the old, dead, trunk and associated canes with extreme care. You don’t want to damage your new canes, which may very well end up resting on the ground for a while. It takes time, but work slowly and carefully. (I find that working through the mess usually requires an hour or perhaps two per plant, so allocated plenty of time and don’t rush.) Eventually, you’ll clean up everything but the two strongest canes.

Now that you’re down to two contestants, carefully look at the canes attached to each of the trunks. You need to consider which trunk has the heartiest canes placed in the right positions for the trellis system you’re using. In my case, I looked for the best trunk with four canes—two upper and two lower. Cut off the trunk you don’t want to use.

It’s important to remember that your plant is frozen and won’t be very flexible during this time of year. Carefully tie the canes to the trellis using a stretchy material that won’t harm the canes. I cut up old, clean pantyhose. It’s stretchy, holds up moderately well in the sunlight, and is inexpensive. Plus, it tends to dry out quickly after getting wet, which means you won’t introduce mold to your plants. You’ll likely need to work more with the canes later in the spring, after they defrost, but before they become productive.

In most cases, mother nature won’t kill your plants. The roots will survive even if the top of the plant is completely dead. Unlike most orchard plants, you don’t normally need to worry about grafts when working with grapes, so using those root suckers is a great way to get your grapes back after being killed off. Instead of the seven years required for new plants, you could potentially get grapes from the restored plants in as little as three years, so the time spent coddling the damaged grapes is well worth the effort. Let me know your thoughts on grape pruning at [email protected].


The Making of a Grape Fence

I have spoken a few times about our grapes (see Pruning the Grapes (Part 1) and Pruning the Grapes (Part 2) for details). A few people have asked for details about our four-cane Kniffin system setup. You can see some pictures of the setup in my posts and there is line art available that shows the setup various places online. However, most posts don’t provide details about the actual construction of the setup.

In my case, I used seven large black locust posts cut from trees my grandfather planted. I debarked the logs using a draw knife and then let them dry for a year before putting them into the ground. Black locust is naturally rot resistant and incredibly hard—even the woodpeckers don’t like it. However, carpenter ants will infest your logs given the chance, but even in this case, they hollow out the center and leave the outside intact. So far, I haven’t encountered a problem with carpenter ants because the grape fence is located far enough away from the woods. Because the posts I’ve used are so strong, I didn’t add the angled end posts shown in a lot of illustrations of grape fences. If you were to buy your posts from a lumber hard, you’d want sturdy 4″ diameter or larger posts. Each post is 9′ long and you bury 3′ of the post in the ground.

The cabling is 1/8-inch galvanized wire rope. You want to use wire rope because it’s made up of many small wire fibers and is quite flexible—making it easier to work with. This size cabling will support six to ten canes without any problem. Make sure you read about the weight capacity of the cabling. Each cable must be able to support a minimum of 50 pounds per cane per cable. So, if you have six canes in a row, the cable must be able to support at least 300 pounds (more is better). Otherwise, you have the risk of the cable breaking as the fruit ripens.

You’ll need some method of clamping the cabling. The method for attaching the cable to the earth anchors and turnbuckles is to create a loop and then clamp the loop. Some people will try to use crimping sleeves because they’re easy to work with and inexpensive. This solution works fine for fencing, but not for grapes. As your setup flexes and breaks into the task of supporting the grapes, you’ll need to make adjustments and tighten the cables. For this reason, you want to use wire rope cable clip clamps instead. I’ve found that the 3/16″ or 1/4″ sizes work best for the cabling used on my setup.

Two turnbuckles help tighten the cables. One turnbuckle for the upper wire and one for the lower wire. The turnbuckles make it possible to make small tightening adjustments as the season progresses (you normally make major adjustments in spring, before the canes become active). You want to keep the cables as tight as possible to help support the canes properly. I prefer a 5/16″ × 9 turnbuckle because it provides enough adjustment potential in most cases. Make sure the turnbuckles you choose can support the weight of the wire rope and canes.

The wire rope is ultimately supported by two earth anchors—one at each end. Both rope wires can go to the same earth anchor. It’s a mistake to assume that you can use a short earth anchor because it will pull out over time. In order to ensure that your setup will remain sturdy, you need a large earth anchor. My setup uses 6 × 48″ earth anchors with attached auger for maximum strength.

An earth anchor the size of the one discussed in this post requires a fair amount of muscle to put into the ground. I highly recommend having a piece of metal pipe to use to help get the anchor into the ground. My piece of pipe is about 30″ long. You put the pipe through the eye in the earth anchor and use it to turn the earth anchor as it goes down into the ground.

The final piece of the puzzle are the screw eyes used to hold the cable at each post. The screw eyes are attached at heights of 30″ and 60″ on my setup. Each screw eye must be able to support the weight of all of the canes and the wire rope. A 2-1/16″ screw eye (size 104) will probably work, but I prefer a larger 3″ screw eye to ensure it will hold up.

This is all that you need to setup a grape fence of the type I use. There are ways to make the fence using other materials and I’m not saying my method is the only method available, but it has worked well over the years we’ve had grapes. Let me know your thoughts on grape fence construction at [email protected].