Background
Below are some notes relating to location, climate and ripening times of grapes grown on this site.
Grape Growing in Scotland
Right: The location of vineyards in Scotland on a map of average summer temperatures as proxy for climate zones. Historical vineyards growing grapes in heated greenhouses are shown in dark red. Vineyards set up over the last two decades are numbered in sequence of opening. Those which are no longer operating are shown in grey, those currently operating are shown in black.
Temperature zones are simplified from: Prior, J., 2010, The Met Office Book of the British Weather, edited by Tempest, S. David and Charles Limited, 160p.
Using the Pulliat Comparison as a Scale
Right: The Pulliat Comparison is an estimate of grape berry maturation (in weeks) relative to the variety Chasselas. Grape varieties such as Foch, Madeleine Angevine, Chardonnay and Seyval Blanc grown in the UK ripen from 2 weeks before, to 2.5 weeks after Chasselas. Varieties usually associated with northerly vineyards, Rondo and Solaris, are estimated here to ripen 1 to 3 weeks before Chasselas, but they are not the fastest varieties. Preliminary results from here (in italics, others from Catalogue des Vignes Cultivees en France website - see links) suggest Dalnivostock Ramming, Jublienka Novgoroda, Michurinets, and Landot 2317, are at least as fast ripening as these commonly grown types.
Polytunnel vineyards in England and Wales grow grapes with ripening speeds of +1.5 to +3.5 weeks on this scale. The shorter season in the north means the limit of polytunnel growing here is approximately +1 varieties. Polytunnels in warmer areas of Scotland would be more similar to the greenhouse here, which extends the season to +2.5 varieties on account of better insulation early and late in the season. By using a range of fast- and slow- ripening varieties (-3 to +2.5) under cover, it is possible to crop table grapes from early August through late October
Growth Degree Days
Right: Heat totals as monthly Growing Degree Days (GDD) base 10 Celsius using 2020 as an example year, for the various growing environments on this site.
Daily GDD = (maximum T+ minimum T)/2 -10, if average T <10, GDD=0
Differences between the greenhouse and polytunnel are due to better insulation of glass/polycarbonate panels versus plastic sheeting in the Spring and Autumn, and differences in ventilation during the Summer.
Timing of Events in the Growing Season
Right: Approximate timing of budburst, flowering, and berry maturation in different growing environments on this site. Growing outdoor vines in shallow trenches which can be covered during frosts/budding coupled with using ultra-fast varieties allows a similar timing of events to vineyards much further south in the UK
