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How and when to prune grapevines
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If you are growing or considering growing grapes, you need to make sure that you give them every advantage and a big part of that includes properly pruning grapes. Pruning grapes should be done at regular intervals and can rely upon multiple pruning methods. You can choose which method you prefer based on where you are growing your grapes and how you want them to be structured.
When to prune grapes
The best time to prune grapes is the beginning of winter. The beginning of winter should be your main pruning season. But, bear in mind that your grapes will need regular maintenance in the form of minimal pruning throughout the growing season so that they can remain as productive as possible.
There are two main types of pruning.
- Guyot pruning method
- Rod and Spur (Cordon) pruning method
Either system can be effective for dessert grapes or wine grapes, grown indoors or grown outdoors. With grapes, you will need to properly prune them and train them and do so at regular intervals so that they can produce high yields and remain under control structurally.
Guyot pruning method
This method is typically used for grapes that are grown outdoors. This system has you form one or two main fruiting arms that grow out of the main stem. This method is usually used for commercial growers but home gardeners can easily set them system up as well.
Rod and Spur (Cordon) System
This method is reserved for grapes that are grown indoors in greenhouses or those that are being trained against a wall, pergola, or fence and is the go-to method for most home gardeners.
When to prune
As mentioned, early winter is the perfect time for pruning because it reduces the risk of your vine bleeding sap and becoming weak. If you prune any other time of the year you will weaken your grapevines which will negatively influence the yield you get. The rest of the year, however, you can train your shoots and pinch out new shoots, and thin your fruit as necessary so that you get bigger grapes by reducing the number of grapes on each vine.
Supporting structures against a wall or inside a greenhouse
No matter where the grapevines are being grown they will need some sort of support system. If you are growing your grapes against the wall or inside of a greenhouse which most people in the Uk do, you can use wires stretched horizontally along the wall you are using or tied between the post in your greenhouse. The wire should be 3mm in diameter so they can support the weight of heavy grapes. You should space it out about 30 centimeters apart. You can thread the wire specifically through vine eyes and screw it into the structure or simply clip it onto existing bars in your greenhouse to form the support.
Supporting structures for grapes grown in the ground
If you are growing in the ground you should construct some sort of post and wire support system with timber posts driven into the ground and the same galvanised wire used in between the posts. The posts should be driven 45 centimetres into the ground or until very stable and spaced about 4 meters apart. You can attach the first two wires about 40cm and 55cm above the soil with all subsequent wires at 30cm intervals the rest of the way up.
By using the system most appropriate for your growing location, you can prune annually to keep the structure in shape, literally and figuratively, and then prune throughout the season for maintenance purposes enjoying ample yields of grapes.