Why is this important? Most vineyards show potassium deficiency, however young vines in many cases produce berries high in potassium like our did, >2,000 ppm. An easy explanation….watering techniques. Early in the season, wen the growth rate is high, much of the potassium accumulates in the leaves. Then the potassium ions are moved from the leaves into the berries later in the season when the fruit starts to ripen. How is this controlled? Try not to water from the time the berries “set” on the vines to verasion (when they turn purple). This will limit the amount of potassium into the leaves that will be transferred to the berries. Due to the smallness of our vines and the shallow roots, I had to water them so they would be healthy. This, I think, shot up the potassium which in turn increased our pH of the berries later in the season. So, next year I will try and not water until verasion.