Harvest is fast approaching, and we're faced with last big question of the growing season -- When do we pick the grapes? A pretty important question to say the least. Grapes picked too early will lack varietal characteristics and flavors, and grapes picked too late can suffer from overly high alcohol. Worse than that, grapes still hanging during late September or October risk exposure to rain, mildew and the loss of the entire crop! If you like gambling, you might enjoy farming.
There are lots of clues in the vineyard to gauge the optimal time for harvest. The first is a simple one. Grape color. When our grape clusters are filled with dark berries and no red grapes are left in the bunch, we know we're getting closer. But even grapes that appear perfectly dark in color are not always ready for harvest. A quick way for winemakers and growers to determine the difference is to simply pluck a few berries off the vine and taste them. We're not just looking for sweetness, but distinctive flavors and firm tannins that will lend themselves to the bold and balanced wines we strive for.
It's not just the color and taste of the grapes we notice, but the seeds too. We want to see a color of dark tan or brown. Any greenish or light brown color to the seeds is a sure sign that it's not time to pick those grapes. And we actually chew on the seeds as well. Brown seeds with a nutty flavor and no bitterness tells us the fruit is ripe and ready to come off the vine very soon.
Some vineyards have to deal with a very unwelcome indicator of grape ripeness. Hungry birds with an appetite for wine grapes. They don't need a chemistry set to figure out when the berries are ready, they just know. Bird damage on vineyards can be a costly nuisance for some growers, and nets, reflective streamers and noisemakers are just a few of the tools in the anti-bird arsenal. Fortunately for us, for whatever reason, the birds seem to leave our grapes alone. Maybe it's the labradors.
But when it comes to selecting a harvest date, we can't just rely on taste, color or the birds to determine when to pick. Winemaking involves plenty of science too, and that's where the refractometer comes in. It's an instrument that gives us the sugar content in the juice, measured in degrees Brix. 1 degree Brix equals 1 gram of sugar per 100 grams of liquid. We pick berries from all over the vineyard to get a large and representative sampling of our different varietals and vineyard blocks. Then we can place a drop of that grape juice onto the lens of the refractometer and hold it up to the light to get an accurate indicator of how close our grapes are to harvest. Light bends differently as it passes through water depending on the amount of sugar in the liquid. The refractometer measures this in degrees Brix.
We're looking to reach a specific degrees Brix measurement before we harvest, with different degrees for different varietals. Depending on how much sunshine we get, the Brix can go up by 1-2 degrees per week. Here are the results from sugars we took on September 18th, 2012.
Varietal Degrees Brix Desired Brix for Harvest
Zinfandel 24.9 27.5
Primitivo 26.1 28
Cabernet Sauvignon 22.6 26
This list reflects the different ripening rates of different grape types in the vineyard. For thousands of years winemakers have opted to plant varietals that would ripen at different times as a safeguard. If it the weather turned bad late in the growing season, hopefully you had already harvested some of your early ripening varietals so the year wasn't a total loss. After some difficult growing seasons in 2010 and 2011, the weather has cooperated beautifully this summer and winegrowers all around Dry Creek Valley are excited about the harvest of 2012. And the refractometer will let us know when that will begin at Collier Falls!