May 13 was unlucky for some English winemakers. That was the stark reality of a late frost last week that saw 25 vineyards suffer frost damage across 90-100% of its vines. The effect of the frost was also seemingly arbitrary – Breaky Bottom which is close to the sea in Sussex had almost total damage, while Rathfinny which is also close had none. Our ‘retired’ Michelin Star restaurateur Roger Jones reports back from Harrow & Hope, Flint Vineyard and Ambriel to see how it affected them and also to see how they prepare themselves for the worst.
“We’ve always known that being more central in the country increases our risk, but we believe this is a price worth paying for getting hotter days throughout summer and picking our grapes earlier and riper.” Henry Laithwaite, Harrow & Hope
A late May frost with temperatures dropping to as low as -5°C is a nightmare for English wineries and last week, between May 11 and 15, sadly it hit over 200 estates with 25 reporting damage between 90 and 100%, one winery was even hit two days ago on May 20th. For Breaky Bottom, near Lewes, Sussex it is the first time that it has experienced frost damage since 1974 and the night of the 13th May caused almost total wipeout. Secondary growth can make good the damage but it will inevitably affect yield and can affect quality.
This period in the calendar is often referred to as the Blackthorn Winter in European folklore, with the saints St. Mamertus, St.Pancras and St Servatius – collectively known as the Ice Saints – having their feast days fall on May 11th, 12 and 13th respectively. But that provides little cheer for those affected.
Seeing the pictures on social media last week I decided to give a few friends a call to see how they had coped and what they do to protect themselves.
Henry Laithwaite at Harrow & Hope, Buckinghamshire
Henry, the amazing pictures we saw on social media highlights the tremendous work which goes into protecting the vines from frost, can you go through the basic format and the work involved with the ‘bouviers’ and what you have learned from the past?
“Yes everything we do now has been a result of losing some 60-70% of our crop in 2016. I think we all go through periods where we say, that will never happen to me. The reality I think is, because of global warming, the likelihood of frost events has increased. Even to those who think they are immune. We’ve always known that being more central in the country increases our risk, but we believe this is a price worth paying for getting hotter days throughout summer and picking our grapes earlier and riper.”
“Our strategy is to firstly plough, inter-vine and plant our cover crops just before we put the candles out. This firstly gives us bare earth to help heat the soil and reduce vegetation over the frost period, which can increase risk. We then distribute 250 candles/ha, which for us is around 1500 in total (it takes us a day); when lit these give us protection to around -2.5°C. We always have a reserve of candles in case we need a few more.”
“When our alarms go off we have a team of five who can get to the vineyard and light them all in around one to two hours. We normally start at the bottom of the hill where it’s coldest and then move to the very top, which is flattest and, again, more prone. Very rarely do we light them all as you get heat drift and protection from the bottom and top for the whole vineyard. The worst bit is putting them out once the sun comes up, but the quicker you put them out the more burn time you save for next time. On average you get a good three to four hours burn from each candle.”
Looking deeper into the issue why is it that, despite looking pretty hardy at this time of year, the vines so susceptible to frost damage? From a simplistic point of view – why did half of my vine die in my garden at home but the herbs and flowers surrounding it survived?
“Put simply vines just aren’t very frost-hardy, and I guess this comes down to cell structure as a result of evolution. If we assume vines originated from frost-free parts of the planet then frost hardiness wouldn’t have been a requirement. Maybe you could create more frost-resistant vines through crossing but would they produce fruit? and if they did what would they taste like? But even within varieties you have different hardiness – Chardonnay is the weakest and Meunier the best with Pinot Noir in between.”
Once damaged is there no hope of recovery and is the damage only for each season? When are you safe with frost and at what stage afterwards if at all?
“Recovery I think depends on at what point the damage happens. If it’s really early in the year then you have a greater chance of the vines catching up at the end. The problem with this year is that we were a month into the season and for the vines to re-grow and catch up ripening is almost impossible in our climate. Then you have the fact that the secondary buds that come through are significantly less fruitful and this is what gives you the biggest impact on yield, even if you did mange to get them ripe. Traditionally in France you aren’t safe until the ‘ice saints’ days have passed which is middle of May. In the UK that’s probably end of May but we’ve never had a frost that late before – but who knows these days!”
If money was no object what other ways could you protect your vines? I have seen in New Zealand helicopters being used, and wind turbines. Would drones with heaters work?
“Helicopters would be the best as they produce heat and mix the air. We’ve looked into the rates but, considering our proximity to housing, I could only imagine the level of complaints we’d get! Turbines are good for radiation frosts where you get a temperature inversion layer and can mix the air to raise the overall temperature. But it’s the air frosts that are the worst and do the most damage in the UK and with those you have to produce heat as you have no inversion layer. Drones sound good but they would have to carry a heat source and that sounds heavy!”
Anything else you would like to mention – did you learn anything about frost control on your travels? I doubt McLaren Vale had many issues
Yes McLaren Vale wasn’t a particularly frost-prone area being near the sea, but I know the Barossa gets hit on occasion as it’s more inland. In my time in Bordeaux it was a very rare event but, as you know in the last few years, it has become more of a problem. No one is safe! The best advice I’ve heard on frost is you have to imagine it as a viscous liquid flowing down a slope, and that if you have something in its way it builds up to twice the height of that obstacle, i.e. a hedge or wall. Something to always consider when planting a new vineyard.
Hannah Witchell at Flint Vineyard, Norfolk
I asked Hannah Witchell, who runs the winery with husband Ben, some questions about how they coped with the frosts last week and whether that changes anything for how they prepare in the future.
How badly were you hit?
“This is the first year we’ve been hit by frost. Overall we estimate we have lost all the new growth on around half of our 26,000 vines. Obviously we’ll be hoping for some strong secondary growth and therefore overall we hope to still get a decent yield, albeit hugely reduced from what we would have forecast.”
How do you prepare for frosts?
“We try and prune the most ‘at risk’ vines last and sometimes spray copper (not this year), both to promote later budburst but this was less relevant this year as all vines were past ‘five leaves unfurled’ by 14th May which was the date of the frost. We spray FrostTech – a Harpin biostimulant that can help but we perhaps weren’t timely enough this year and this only tends to be reliable in less severe conditions. We also try and mow cleanly under the vines to allow air movement and, again, in the worst hit area, this was something that was not completed due to time constraints. The frost this year affected vines only in the lower areas of the sites so airflow is a key consideration here in risk years.”
And what are your thoughts for the future in frost control?
“We will be looking into more robust protection measures, particularly use of bougies (paraffin candles), a sprinkler system or heated cables along the fruiting wires.”
To more cheerful matters how are you celebrating English Wine Week?
“This Friday 22nd May we’ll be taking part in a live chat and tasting with @WineTimeLondon on Instagram to celebrate East Anglia Wine Night and what would have been the start of English Wine Week. You can pre-order our wines to taste alongside us, including our brand new Pinot Noir Précoce which is being release on Friday 22nd May.
Wendy Outhwaite at Ambriel Sparkling, West Sussex
“No frost damage here. We lit burners on Wednesday night just in case, but we didn’t get to freezing in the vineyard. I’m hoping that it’s now safe but it just shows that my gardening grandmother was right: ‘ne’er cast a clout ‘til May be out’.”
“If the primary buds are damaged then the secondaries will come through but the fruit is unlikely to be as good and yields will be down because the vine has already used its force on the primary buds and they will need a few more weeks to ripen (which they may not get before the vine shuts down for winter and October is not good ripening weather).”
Good to hear Wendy, and just shows how arbitrary the frost this year seems to have been in where it affected. And I couldn’t think of ending this report with anything better than Wendy’s social media post last week….