As we are now seeing (finally) some sun, after a long wet, windy and cold winter, we can start to hope that our fragile flowers in the garden no longer need protection. The wine growers in the northern hemisphere can finally get a full night sleep.
On cold spring nights, across this region, as temperatures fall below zero, vineyards everywhere will be alive with frost beating techniques: candles, small bonfires, hot air blowers, artificial fog, some methods more romantic than others.
Some vineyard owners spray water through sprinklers to keep the air warm, so frost does not form. Others move air in the fields as much as possible to warm up the local immediate environment, with big fans running throughout the night. The posher wineries – such as those found in the Champagne region – even resort to flying helicopters over the fields as air displacement helps prevent frost apparently; an expensive method usually reserved for the more valuable grape!
The more common frost-proof candles are placed between the rows of vines; a great way to stave off frost and it looks so pretty too. Large paraffin candles. Known as “Bougies” give off enough heat to create air movement which prevents a frost pocket forming.
Our local English wineries use bonfires and these may well need to be used throughout April and into May. Talking to Black Chalk in Hampshire, we heard how as the vines stir from their winter slumber, entering the delicate bud burst stage, they are fragile making April and May a tense time. The team there are constantly monitoring night time temperatures and prevailing weather patterns, so during frost nights, when the temperature dips worryingly low, the team battles throughout the night to keep the vines protected from the elements. They use “frost guards” which act like a giant rotating hairdryer, blowing warm air around the vines to keep them warm, They tell us that they now have a secret weapon “The Fog Dragon”, an enormous sealed chamber containing a blazing fire which exhales thick, protective smoke from its spouts as it glides up and down the rows. A sprinkler system flanks the Fog Dragon, letting the smoke hang low like a comforting blanket across the vineyards, shielding them from the icy grip of frost.
Vineyard workers stay up all night during this period, checking the weather constantly, so that in the very early hours, the team can rush out and activate the frost prevention schemes. Another labour intensive exercise to make sure the bottle of wine we consume with our Sunday roast is perfect.
Conversely, the icewine growers need frost!
Icewine / Eiswein) is a sweet dessert wine produced from grapes that have been frozen while still on the vine. The sugars and other dissolved solids do not freeze, but the water does, allowing for a more concentrated grape juice to develop. When pressed there is a smaller more concentrated very sweet juice. Icewine is not to be confused with some other pudding wines such as Sauternes (France). Tokaji, (Hungary) or Trockenbeerenauslese, Germany, where the grapes are left to rot, well, be affected by botrytis or noble rot. Ice wine growers need to make sure that the grapes do not suffer from any rot. This makes icewine production much more complex; if frost does not come before the grapes rot then the harvest is lost. It may also mean that the whole crop needs to be picked within a few hours, at a moment’s notice, on the first morning that is cold enough.
The grapes for icewine must only be harvested when they are frozen naturally and the temperature must be -8 C (20°F) or below when they are picked. This results in relatively small amounts of ice wine being made worldwide, making icewines generally expensive. It is made only in the regions is the world where temperatures are low enough regularly.
The largest producer of ice wine is Canada followed by Germany.
So frost is both an enemy and a friend to the winemaker.
