Tony Dickerson answers your questions
Q Which grapevine variety should I grow on my new pergola? Ron Jack, Sandy, Bedfordshire
A If you want to grow a productive vine for wine or dessert you won’t be able to share the space with other ornamental climbers. Grapes are just too vigorous and need regular pinching back to manage vigour.
Even with climate change, white varieties offer the best chance of success. ‘Madeleine Sylvaner’ and ‘Müller-Thurgau’ are the traditional standbys for wine production in this country but ‘Bacchus’ is rapidly establishing a reputation as the UK Sauvignon Blanc. For muscat-flavoured, dual-use grapes consider ‘Siegerrebe’ and ‘Phoenix’, another newer variety which is proving to be very successful. Black grapes are more problematic in our climate but ‘Regent’ is a good bet for dessert and winemaking. You’ll need to train a number of stems up and over your pergola to form a permanent framework of woody growth. After the first season cut back all growth by two-thirds after leaf fall and repeat this each year until the available space is filled. Tie in laterals (sideshoots) from the main stems and allow them to grow to about 60cm (2ft) long before pinching out the tips. When the framework of main stems is established allow two bunches of grapes to develop on each lateral. These laterals should be spaced about 60cm (2ft) apart. Pinch the shoot tip out once a couple of leaves form beyond the second bunch. Sub-laterals growing from the laterals should be pinched out at one leaf.
Regularly pinch out all surplus growth as the grapes develop during the course of the summer. Without this management the vine will become a mass of foliage and goodness will be diverted past the grapes to produce more leaf growth.
Famously, grapes grow on what are often quite poor, dry, chalky soils but to get them established in the garden dig out a planting hole in your courtyard, break up any compaction in the bottom and fill with a good quality John Innes No 3.