The main pruning season for grape vines is early winter, but they need regular pruning and maintenance throughout the growing season to keep them manageable and productive. The two main pruning systems are the Guyot system and the rod and spur (cordon) system.
Grape vines, whether grown for dessert or wine, and indoors or outdoors, need regular pruning and training to keep them under control and producing good fruit yields.
- Grapes grown for wine and dessert grapes outdoors are usually pruned and trained according to the Guyot system
- Grapes grown against walls, fences, pergolas and those grown in greenhouses are usually pruned and trained according to the rod and spur system
- Grapes grown in containers are usually trained as standards
When to prune and train
The main pruning time is early winter (late November or December). Training and pinching out of new shoots, as well as thinning of fruits, is carried out in spring and summer.
Putting up supports
No matter where you grow your grape vines, you will need to put up some sort of support system.
Against a wall or in a glasshouse: Use 2-3mm diameter galvanised wires stretched horizontally along the wall or between the glazing bars of the glasshouse. Space them 30cm (1ft) apart. Thread the wires through ’vine eyes’ which are made specifically for this purpose and can be bought to screw into wood or masonry, or to clip into the aluminium glazing bars of the glasshouse.
In open ground: Construct a post and wire support using 2m (6½ft) x 10cm (4in) pressure-treated timber posts driven 45cm (18in) into the ground and positioned 4-4.5m (13-15ft) apart. Stretch 2-3mm diameter galvanised wire between the posts, fixing the wires to the posts with screw-in vine eyes. Attach the first two wires 40cm (16in) and 55cm (22in) above ground level. Subsequent wires should be double, secured on each side of the posts, and at 30cm (1ft) intervals from the lower wires.
The pruning systems
The Guyot system: This form of training has either one or two fruiting arms growing from the main stem (single or double Guyot accordingly). It is used for vines grown outdoors, either dessert or wine cultivars.
The rod and spur (cordon) system: This system is usually used for indoor grapes in glasshouses or conservatories, and for growing grapes against walls.
Growing grape vines in containers: Where space is limited, vines can be pruned and trained as standards, with a single stem with a head of branches at the top. Standards lend themselves easily to container cultivation.
To train a standard:
- Train the main stem up a stout bamboo cane. Remove any excess stems appearing from the base
- Allow side branches to develop on the main stem for the first one to two years
- In the third winter, remove all side branches from the bottom and middle of the stem, leaving only the top branches. Allow five to six side branches to develop at the top
- Prune the side branches to five leaves, not allowing them to get any longer
- Prune any side shoots developing form the side branches to one lea
- Only allow one bunch of grapes to develop in the first cropping year, removing any others that start to develop. In subsequent years, allow one bunch of grapes per side branch
- In early winter, prune the side branches back to two buds
Indoor grapes commonly suffer from the fungal disease powdery mildew and the similar-looking disorder known as shanking. They can also suffer from grey mould (Botrytis), downy mildew and various glasshouse pests, including scale insects and red spider mite.
Vine erinose mite is a common but luckily harmless pest that causes parts of the leaf to bulge upwards, appearing blistered. On the underside of these areas there is a dense mat of fine, whitish hairs, which darken to yellowish-brown during the growing season.