The Frost Chronicles – a winemaker’s perspective

Chopper swirls warm air down to mix with colder air sitting underneath

The sight of bud burst at the start of spring is something we all look forward to during the cold long winter here in Marlborough. We can dust off the shorts and start wondering what Mother Nature will bring us this year to work with at the winery. It also happens to be when Mike our viticulturist starts to look a little edgy and is constantly checking the weather forecast looking for any signs of Jack Frost making an appearance.

Bud burst for us this year began with the Chardonnay in our beloved Renwick vineyard in the first week of September. Our Renwick vineyard is tradionally pretty much frost free, so I was very surprised to hear Mike on the phone organising a Helicopter to fly up and be located in Renwick to do battle with an impending frost!!” Bloody hell” I thought, must be looking like a really cold one tonight!! We have a couple of different ways we can battle the frosts, firstly we can light diesel burning frost pots, which are effective but limited in the event of a really cold night, secondly we have installed frost fans (they look like a windmills) in our coldest vineyard Kaituna but even they can lose the battle on their own if it’s really, really cold. Thirdly there is using a Helicopter to hover over our precious vines and push warm air from the inversion layer above the vineyard down to prevent the new bursting buds from freezing. In the last couple of weeks we have used all three methods to give our vines the best chance of getting through the frost season unscathed.

To Mikes surprise I offered to be his wingman for the night in Renwick? Standing round in the vineyard under a helicopter blasting freezing air right down on top of you is not something I thought I would put my hand up for to be honest. Mike accepted my offer and suggested I wear all of my warmest clothes, hats, gloves and thermals! What have I got myself into???

Once the chopper was confirmed we raced out to the vineyard to install our frost lights on the posts throughout the vineyard. These are a genius kiwi invention that consists of a little light that glows green when it’s between 1 and 3 degrees, white when it’s between 1 and 0 degrees, red when its 0 degree and they start flashing red when its negative 1 and below. The idea being that the chopper pilot can quite simply fly around the vineyard changing the lights from flashing Red to white if not green. Once the lights were installed we filled up the Frost Pots with diesel and positioned them around a block of very young Chardonnay that we couldn’t fly over due to trees and a neighbour’s house. Now we cross our fingers and hope we don’t need to use either method at all tonight.

The Helicopter arrived just on dusk and parked up on the headland of the vineyard awaiting our instructions. At this point Mike and I head home hoping to not be back………………7.30 pm I get a text from our weather station telling me its 1 degree already and dropping fast. I race around the house trying to find all my warm gear, fill up the thermos then off to the vineyard I go. By the time I get there 15 minutes later the lights are glowing white and it’s bloody chilly. Mike and I both have hand held thermometers and start walking up and down the rows double checking the lights against our thermometers, the temperature seems to have stabilised at 1 degree so we decide to go a light a little fire to keep warm. At 10.30 the lights are starting to change to Red so it’s time to wake up the pilot, light the pots and get things moving. Within 5 minutes the chopper roars into life and lifts off. For the next hour he slowly fly’s up and down the vineyard pushing the warmer air from the inversion layer down onto our precious chardonnay. Once the lights started to constantly glow white we called up the pilot and get him to land.

 

Sweet lets go home I was thinking to myself, it was then that Mike informed me that there is always a drop in temp at dawn that we now need be cautious of. I headed back to the winery to fill up the thermos, get some more fire wood and more batteries for my torch. For the next couple of hours we spent our time standing around the fire and walking round double checking the temperature. 2.45 am rolls around and the lights start to change back to red, back on the phone to the Pilot and here we go again. At $1700 an hour the decision to send the chopper up is not something Mike takes lightly, but the thought of losing some of our best fruit and buggering our season would certainly be at the forefront of Mike’s decision making process.

The next hour and half were very noisy for our neighbours but I think most people in Marlborough understand what’s at stake and most of them are very understanding. At about 4am a very light breeze starts to pick up which is good news for us as the temperature slowly starts to rise above 1 degree and we could land the chopper. We stay around though just in case the wind drops at dawn and the temperature plummets.

Thankfully this did not eventuate and as the sun started to rise I could see a smile on Mikes face that told me all was well and we had kept Jack Frost at bay…… for tonight anyway.

 

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