Over the autumn and winter, a considerable amount of groundwork has been taking place in our vineyard, the product of which will be a new Frost Protection System that we have been trialling and working on for the last two years.
As with all fruit growing (and gardening!), late spring frosts when buds and shoots are just starting to grow can devastate a crop. Traditionally, lighting hundreds of Frost Candles overnight (or “Bougies” as they are known in France from where the technique comes) has been the solution of choice. The heat generated creates airflow and prevents frost from settling. It is also quite a magnificent sight as you can see below. Unfortunately it comes with an environmental impact – not to mention the hard work of getting up every night to light a thousand candles which we did six times this year!
As founder members of Wine GB Sustainability in Viticulture, we are pioneering a nature-based solution which uses water spray instead. You would be forgiven for wondering why we want to spray cold water onto the vines in sub-zero temperatures! The rather fascinating reason for this comes in the form of an exothermic reaction and uses the fact that, when water freezes, a small amount heat energy is released. As water is continuously sprayed over the vines, the freezing action therefore helps protect them, with the ice itself creating an igloo effect – the air temperature can drop all the way to -5 degrees or more but the vines will remain at a balmy level just around freezing!
Although used by orchard growers for many years, we are among the first to bring it into a UK vineyard, working with a specialist irrigation company called Netafim (based in Israel and experts in precision irrigation for obvious reasons). The main problem with this technology is water capacity, the answer to which came in the form of looking back at Chilworth Manor's history. When we did the restoration work on the Manor, we found that the monks had used the natural geography of St Martha’s (sandstone on top of clay) to collect natural run-off from the slopes above and store it in the ponds they built 500 years ago.
The vineyard itself used to have a pond around 300 years ago and, when we planted the vines, we installed a network of drainage pipes to draw off several million litres of water a year. To answer the water capacity problem, we just had to build some form of reservoir to hold a fraction of this quantity for the late frost season of April and May and, sensitive to visual and environmental concerns, ours is made from recycled steel and installed underground. As the water is used on the vines, the excess returns to the soil and the reservoir fills again naturally.
Going forward, this system will be our main protection system taking over from the frost candles. We may still use the candles during special weather conditions, but from now on will aim to use refillable candles allowing us to recycle the tins used.