"Keep measuring. Don't let the pH go above 3.3 with
whites or 3.5 with reds. Harvest when the Brix:TA ratio is as close as
posible to 30:1-35:1, and when Brix times pH squared is as close as
possible to 200 for whites and 260 for reds."
It is heavily variety dependent for me. I harvest Edelweiss and Brianna almost exclusively by brix, with a spot check on pH hoping it is within ear shot of 3.0. I harvest St Croix mostly by pH and the state of the skins, with a check on sugar between 18 and 20 brix. Marquette and Frontenac are governed mostly by TA, but I don't bother measuring it until sugar and pH indicate that it may be time. Frontenac Blanc and La Crescent are a combination of sugar, pH, and how the sun is impacting the berries. I pick La Crosse based on sugar and pH, with an eye towards thunderstorms that might split the berries. Petite Pearl is governed by when the Frontenac was harvested. Don't get too excited about measuring his sugar and pH until I get the Frontenac off the vine.Is this the most crucial question with no precise answer yet?
When is your time? Color? sugar? acidity?
We don't want to miss the right moment this year, any advices will help