If you are interested in getting quality fruit, it is important to learn how to properly prune grapevines. If you do not prune your vines, you will not get a good fruit crop. Without pruning, there will be too much vigorous leafy growth, and few poor-quality fruits.
Now, if you are standing in front of a tangled mass of grapevines, the idea of pruning them might seem intimidating for both new and seasoned gardener alike. Fortunately, pruning grapevines is actually quite easy, and you only have to do it once a year. Grapevines are an excellent first plant to learn pruning on.
Grapevines are vigorous, and very forgiving. Even if you make a mistake this year, the plant will give you the chance to fix your mistake the following year. Every year they put out vigorous new growth, and when you prune them you will remove most of it. The biggest mistake people make pruning grapevines is actually not removing enough wood.
A little secret to remove the mystery of pruning
Before we get started on the specifics of pruning, we have a little secret to share that will take the mystery out of pruning most plants. If you take the time to observe and understand what type of wood a plant flowers/fruits on, it will give you a good indication of how and when you should prune.
Aside from creating proper structure or desired shape, understanding this variable is the key to pruning most ornamental and fruiting plants. This understanding is the key that unravels the mystery of pruning and becomes your blueprint to follow. Pruning will seem a lot less abstract and intimidating if you understand this.
Some plants flower on new wood, and some plants flower on old wood. If we remove the wrong type of wood, we will get no flowers or fruit.
What do we mean when we say ‘type of wood a plant flowers on’?
New wood is defined as this year’s growth, as in the growth that will happen once the plant starts growing in the spring. Old wood is defined as last year, and previous years wood. Last year’s wood is 1 year old wood. The wood from the previous season is 2-year old wood, etc.
If you are unsure what wood your plant flowers on, pay attention when they are flowering, or look for remnants of old flowers/fruit during the winter. Some plants are very obvious and straightforward. Others, like kiwis, can be tricky. Kiwi’s for example, happen to flower on new wood with the caveat that it is only new wood growing off of 1 year old wood.
Where and when the flowers are formed is the main underlying guidance on not only how but also when a plant should be pruned. Plants that flower on new wood including grapes and most deciduous flowering shrubs flower should be pruned in the winter/early spring. This promotes the maximum amount of flowers as your pruning stimulates the plant to produce a lot of new growth.
Plants that flower on old wood, such as azaleas or forsythia, should be pruned during the summer after they have flowered. This way they have time to put on new growth and set their buds. These plants typically go into the dormant season with their flower buds already made. If you prune them in the winter you remove all their flower buds for the year.
Grapevines flower and fruit on new wood.
In the case of grapes, they fruit on new wood. Canes that grew last year will not fruit this year or ever again. This is our guiding principal when deciding what wood to remove and what to keep on a grapevine. Anything that we don’t need for structural purposes needs to go. Otherwise this old wood is just wasting the plant’s energy by drawing nutrients away from the canes that produce your crop. This reduces your potential crop.
Since grapes flower on new wood, we prune them late winter/early spring while the plant is still dormant and before they start growing. We do not want the branches we will be removing to flush out in the spring. Removing them after they leaf out wastes the plant’s energy that could be going to producing productive fruiting wood.
Grapes need a trellis to be productive
You have several different options for trellising grapes. The simplest trellis to install and train vines on is a simple single wire trellis. This is the method used by most commercial vineyards and is the trellis design we will be using for this tutorial. It is simply two (or more) braced posts with a wire strung between them. This trellis system makes pruning a breeze. They are also easy to mow around and maintain. Plus, with even the most basic DIY skills you can inexpensively construct one yourself.
You can also grow grapevines on other support structures such as pergolas or arbors using the same principals described here. The main difference is that the vines will grow flat across the top of the pergola rather than draping down towards the ground like a curtain.
Year 1 your purpose is to select a nice straight, sturdy trunk.
If you just purchased a bare root grapevine to plant, most likely the nursery will have trimmed it to a stick approximately 1 foot tall. When the plant starts actively growing in the spring select the best shoot and remove all the other shoots. Tie the chosen shoot to a stake, pergola post or trellis. The idea here is to get that one strong shoot to grow straight up to the top of your trellis. This will be your grapevine’s permanent trunk, so try to pick a good sturdy shoot growing in the desired direction.
Now, if you purchased a potted grapevine, you will likely have an unruly cluster of shoots to work with. In this case, it will be your job to trim the plant back to a single shoot with several buds. Grapevine buds are quite easy to see, so this task is not difficult.
It is best to do this pruning after the severe winter weather is past as grapes can sometimes get cold damage. Waiting will allow you to select a live healthy shoot to keep whereas if you prune too early you risk the one shoot you saved dying back. Once the vine starts growing you repeat the same process of selecting and training the best shoot and removing all others.
Year 2 your purpose is to develop straight, sturdy permanent cordons
At this point you will hopefully have a big long shoot all the way to the top of your trellis. If your vine has reached the top of the trellis, you will top the vine to encourage it to grow lateral shoots. If the vine has just barely reached the top of the trellis, trim it to have as many buds as possible above the wire. If it has gone far past the top of the wire, trim it down to 4-5 buds. Lay this short piece of vine over and secure it to the trellis.
If your vine grew vigorously enough to produce side shoots at wire height, you can select two of the best side shoots to tie to your wire. Then, trim the top off the vine just above those shoots. Trim the side shoots you selected back to a few buds. Remove all other side shoots. If there are no suitable, strong side shoots, remove all the side shoots and then trim the top to 4-5 buds and secure it to the wire.
If your grapevine did not reach the top of your trellis you will need to repeat the year 1 pruning process. Trim the vine back to a short stub with several buds. This year the vine should have a larger more established roots system and should reach the top of the trellis.
During the summer of year two you should select the best side shoots near your trellis wire and train the vines along the wires. Once they reach the end of your trellis, you can trim off the ends.
Year 3 and beyond you’re pruning for fruiting wood
By year 3 (or 4 if you had to repeat year 1), you should have your horizontal cordons established. The goal from this point forward is to encourage new fruiting wood to grow off these cordons.
Trim back all the side shoots from your trunk, and all the shoots from your cordons back to near the stem. Be sure to leave a short stub with a few buds on it. These buds are what will grow the shoots for this year’s fruit.
You will repeat this process of trimming off all the side shoots back to short stubs every year from year 3 forward. You can also thin out any weak or overcrowded branch clusters. If after several years one of your stubs gets too long and unmanageable, simple trim it off back to a bud near the stem and allow a new stub to form.
Remember, grape vines only fruit on new wood. Canes that fruited last year will never fruit again, so we want to remove them. If you allow them to stay your plant will become unruly, unsightly, and will produce less, smaller fruit.
Alternative technique that works better under some conditions
Some grape varieties do not fruit well when cordon pruned and perform better when cane pruned. Some cooler climates may also lend themselves better to cane pruning. If that is the case for you, you can trim your vines slightly differently than we described above. This method is almost as simple. It just requires a bit extra work because you create new cordons every year.
In a cane pruning scenario you would create a permanent trunk up to your trellis wire the same way we described earlier. Then rather than creating permanent cordons, each spring when pruning, you would select the best 2-4 shoots growing from the top of the trunk. Trim them to 8-10 buds long (typically a few feet) and tie them out onto your wires. Try to choose vines that are medium thickness with lots of buds close together. Avoid spindly ones, and also avoid very large shoots with widely spaced buds.
It is also important to leave a short cane or two cut down to two buds right at the top of the trunk. This cane is what will grow the new cordons for next season. Next year, you remove your cordons that fruited back to the trunk and replace them with the new ones produced by your short cane pieces.
If you aren’t sure which pruning method to use. Try one, and see if you like it. The beauty of grapes is that they are so forgiving, and you can always change your mind next year.
We hope that this gives you the tools you need to successfully prune a grapevine into a productive, and attractive addition to your garden.
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