Swollen wine buds

Oh my, really nice warmth mixed with cold temperature changes! For now, the warmth will have to wait, as premature budding involves some risks. Here, where I am, they say that the risk of frost extends all the way to around June 10 with so-called 'iron nights'. The biggest risk is that you can lose an entire harvest and thus the entire season is in vain. In some cases, the secondary shoots can develop and yield a harvest, but this differs between grape varieties and often yields a smaller harvest in any case due to the delayed development period.

Different bud stages
When the bud still has its hard shell around it, it can withstand temperatures down to -8 degrees and as long as the bud stays tied, it can withstand these fairly cold temperatures. The critical period begins when the bud enters the hairy stage when tolerance goes up to -2 degrees. Then the bud/shoot can withstand this temperature into the green stage when the bud opens and until the leaves start to become defined.

Heating, fans and irrigation
You can use different types of fire to ward off frost. The trick here is to keep the air moving, not necessarily heating the air. That's why you can also use large fans that are placed outside to stir the air. When it's frosty, it's often really still and starry, have you thought about that? In the Moselle Valley, which is known for its steep vineyards, they place huge amounts of marshals in the rows because it's almost impossible to get larger fire engines up when the slope can be all the way up to an incredible 70 degrees. In the Loire, on the other hand, there are fire trucks that are driven around and placed at strategically chosen places in the vineyard, and my colleague from Åhus vineyard put a fire barrel on a trailer behind a tractor and drove around last spring. I'm going to try both of these last ones, how difficult can it be to build a fire truck?

Irrigation is a method that involves some costs in installation and in the consumption of both electricity and water but seems to work with good results, from what I have heard. It is based on an irrigation system being installed along the vines (it therefore requires a certain age of cultivation) where small sprinklers are located at each vine and "spray" water around buds and shoots. The goal is therefore that ice should form around buds and shoots because this acts as a protection against frost and apparently(!) a certain amount of heat is produced when ice forms. Unbelievable! An example of this method is at Ästad winery outside Varberg.

Situation report from the vineyard on Selaön
Do you see that the upper bud is in the hairy stage and the lower one is in the bud bursting stage?