When to harvest?

The busiest and most crucial period in our vineyard has begun. I have seen grapes changing colour and so veraison is underway. But how do we know when is the optimal time to pick? And what should we be doing now to prepare for harvest?  

Most winegrowers in addition to the obvious signs, their “instinct”, and the interest of wild animals especially birds, also take into account measurements of sugar, tartaric acid (TA) as well as the pH of the grapes. Since these measurements differ for different varieties and the micro-climate of each vineyard, each winegrape grower should know her ripe grapes' optimal values. According to some literature, the optimal levels for red wines are Brix: 22, TA: 0.75, pH: 3,4; and for the white grapes Brix: 20, TA: 0.7 and pH: 3.2. This I will have to develop as I monitor annual harvests. Eventually, I'll need to buy a pH and TA tester. 

I have not tested before and, as a result, we lost our first tiny harvest to birds, our second harvest was spot on and our third harvest was too early. So I finally bought a refractometer, one of the most common tools for winegrowers to measure the amount of sugar in the grapes. I have used it to measure the sugar content at the various stages of wine maturation and it's pretty easy. What I need to do is start measuring now so that I have an indicator of increasing sugar content. Here's a good article to refresh knowledge about how to read a refractometer and more. 

Aside from monitoring grape ripeness, I will also be monitoring the weather and the appearance of diseases and pests. Botrytis becomes especially problematic after the grapes attain 8% sugar content. As we are an organic and natural vineyard without use of pesticides or other chemicals, I will have to remove anything that is affected immediately. That requires daily vigilance in the vineyard from now until harvest. 

I'll have to prepare all the tools and equipment as well and clear space for working. We really need a shed for the winemaking, as we've outgrown the house. 

Meanwhile, Spain has reported its earliest harvest ever.