Our lecturers at Plumpton College drone on about site selection as being the most important element to consider for any vineyard site. That was highlighted last week when on the night of the 3rd/4th May, we experienced a late frost in many parts of southern England.
Late frosts are really bad news for vineyards and vines. It is like putting salad leaves into the freezer. The cold freezes the water in the plant cells killing them and leaving then shrivelled and brown. To mitigate this risk you need to choose a site on a slope, which will encourage the frost to drain away down the slope, avoid low lying areas where frost will settle, and try and get close to a river, or even a road, which helps move the frost away. Being close to the sea can help, as the sea raises the temperature of the surroundings. If you don’t have any of those then you will need to deploy “counter measures”. In New Zealand they use helicopters to force warmer air down onto the vines to disperse the frost. This sounds expensive, dangerous and could cause more damage to the vines with the down draft. Many people use small heaters which help raise the temperature, whilst other blast hot air into the vineyard from large gas fired fan heaters, or they use wind turbines to more the air around. In Martinborough in New Zealand they use water sprays to prevent frost damage. However, the cheapest way to avoid frost damage is to select your site very carefully. Like any property purchase it’s location, location, location.
We were working at Rock Lodge vineyard last week and there was some damage to younger vines on the lower slopes but most of the vineyard was okay. I hear that some vineyards in Kent and Sussex experienced some damage but hopefully they will recover.
In Germany temperatures dipped to -5oC on the same night and according to the German Wine Institute some vineyards experienced the worst frost damage for 30 years, since back in 1981 when 90% of vines in Germany experienced frost damage.
Late frost in May is not that unusual. I remember we had a very hard frost in May 2009. Luckily Rathfinny didn’t seem to suffer from the late frost this year. The minimum temperature recorded on our weather station on the night of the 3rd / 4th was 6oC.
All we need now is a bit more rain, because the wheat is really struggling, along with the mustard we planted a few weeks ago as a cover crop, more on that later.