Many wine lovers have wondered if there is an easy way to tell one grapevine variety from another when visiting a vineyard. It would be fairly easy if we all had photographic memories and could remember the leaf shapes of each variety. Or if we spent our days working in vineyards. But barring those options, leaf coloration in the Fall is probably the easiest way.
The reason it’s much easier to distinguish one variety from another is because Autumn leaf color and the time of the leaf color change vary by grape variety. The change in color is due to the movement of sugar from the leaves to the roots near the end of the vegetative cycle, in preparation for winter. Without sugar nutrients the leaves lose their healthy green color and eventually die off.
Additionally, older and better quality vines for wine production tend to show more vibrant colors than younger and lesser quality vines. The reason for the more vibrant color in old vine leaves is that old vines synthesize more polyphenols than young vines, and these extra polyphenols result more vibrant leaf colors when the sugar migrates away.
The energy in the form of sugar from the leaves is kept in the roots during the winter. When the vegetative cycle starts again in Spring the vine will consume this energy/sugar to grow new leaves and sprout buds. The new green leaves are able to fuel the rest of the vegetative process through photosynthesis.
In the old days in Spain when viticultural knowledge was less scientific and precise, vineyards were planted with “field blends” rather than separated into specific varieties in specific plots. So if you see a multicolored plot, it is most likely a very old vine “field blend” of different grape varieties.
Later, as knowledge grew, varieties were separated and planted into the most advantageous plots for each variety. For instance, the white grape Viura tends to do better on slopes, so you will often see plots of Viura planted on sloped sections of vineyards that are mostly planted with the red grape Tempranillo.
The other key factor to consider when viewing vineyard colors at any particular moment is that each variety of vine has its own vegetative cycle length. For instance Tempranillo has a fairly short, early ripening vegetative cycle, so its leaves change color before those of Garnacha, which has a longer, later ripening cycle. So below you will see that although most of the photos were taken within about a week of each other, the Garnacha leaves are still mostly green and have not fully changed color yet.
Below is a photo catalog of the foliage colors of the primary vine varieties in Rioja.
White grape varieties, in order of decreasing importance in Rioja:
Red grape varieties, in order of decreasing importance in Rioja: