Monitor the nutritional status of vineyards by soil and leaf tissue samples. Soil samples are ideally taken in late summer or fall since the soil pH is lowest at this time. Leaf samples should be taken in June and early July. Each sample should be a single cultivar of vines of approximately the same age and vigor. Collect a double fist full of mature leaves located opposite fruit clusters on fruiting shoots. Place in a paper bag and take these to your county Extension office for shipment to the lab in Athens. There is a fee for leaf analysis samples.