Mild Winters and Early Bud Bursts.

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Is a mild winter really that bad? After spending many years in Melbourne I had only just moved back to Hobart in February 2023. Although the city had changed slightly and there was more traffic on the roads I could count on one thing remaining the same, that winter would be bloody cold, right?

Looking back over the past few months I remember telling myself every week "next week will be colder" but the ice cold winters I had grown up with never made an appearance. It was an oddly mild winter with days that felt almost spring-like but what effect does this have on vignerons and vineyards?

After vintage finishes vines drop their leaves and go into dormancy however for this to occur the average air temperature needs to drop below 10 degrees celsius - something that we did not have a problem with here in Hobart luckily. However the mild winter (and record high winter temperatures) saw that bud burst would occur earlier than normal with buds having already starting to bud around Tasmania. You would think the earlier budding which results in a longer ripening period would be a positive (which it is) however this now leaves all vignerons prone to frost! Although average temperatures have been warmer we are still seeing very cold evenings and early mornings. But what can vignerons do to mitigate the risk of frost to ensure their new buds get the most chance of producing pristine fruit?

When frost threatens there are several options that can be deployed to prevent the death of new buds. These options are water sprinklers (aspersion), wind machines and lastly, oil or propane gas burning heaters and wax candles. Water sprinklers otherwise known as aspersion is the process of running sprinklers throughout the evening when frost is due to set. As water freezes around parts of the vine it releases latent heat which protects the vine and new buds. Wind machines are essentially larger fans which pull warmer air from above down to the ground level. thereby raising the temperature enough to prevent frost. This same effect can also be achieved by helicopters albeit a more expensive option! The last option is placing oil or propane gas burning heaters and wax candles throughout the vineyard and lit when there is risk of frost. - Jeff

(Aspersion)