Dr. Dave Miller Michigan Wine Blog
Summer Blog 2017
Grapevines during summer:
Just a few short months ago the vines were just coming out of their dormancy to begin the growing season. Seemingly overnight they went from small shoots emerging at the buds to a trellis full of leaves and fruit that are changing daily. So what goes on in the vineyard this time of year and why is it important? During the dormant season, we prune the vines to remove most (over 90%) of the buds that can produce fruit. If we don’t reduce the vines crop potential, too much fruit will be produced and it won’t ripen properly for wine or any other purpose. Over – producing fruit also weakens the vines going into winter making them more easily damaged by cold temperatures and, it reduces the vines crop – potential for the following year. When this happens the vines go into a “biennial bearing” cycle where a big crop is followed by a small crop which is then followed by a big crop and so on.
Once the buds we left at pruning open or “burst” the shoots start growing and the young grape clusters emerge. At this stage they are only flowers that must bloom and be pollinated to make grapes. So early in the season those of us who grow grapes and other fruits are always watching the weather conditions and hoping for good pollination weather during bloom. This year the weather was good and the grapes set well. That sets the stage for a good crop and is typically complete in southwest Michigan by the end of June. Once the crop is set the shoots keep growing and the young grapes grow rapidly. By mid-July we are in the vineyard estimating the crop to see if there is further crop reduction required to produce ripe grapes and good wine. In our vineyard we have been thinning fruit and small, weak shoots to open the vine leaf canopy to sunlight. At this time of year it may seem like a waste of time to expose the fruit to sun but, we are planning ahead for fall. We are removing some leaves around the clusters of grapes in addition to removing small shoots that crowd the vine canopy. We know that in September and October the days will be much shorter. The sun will be lower in the sky and its rays less – intense. There will be dew in the mornings and, if the fruit is hidden under leaves, it will stay cool and wet most of the day. By removing shoots and leaves that aren’t necessary, we insure that the fruit warms in the morning with the suns first light and actively ripens all day. It also helps the grape clusters dry out so there is less chance for rot to begin. The sun-warmed grapes ripen much faster and have better flavor than fruit hidden in the shade of leaves. So all of the work we are doing now is in preparation for ripening in the fall. By thinning fruit and opening the vines canopy we insure the crop is in balance with the vines ability to ripen it and, that it can take advantage of the cool autumn days to fully ripen our crop. The result is the wonderful wines that you enjoy from our little patch of heaven in southwest Michigan. We hope you enjoy drinkinh the wine as much as we enjoy making it.
18 July 2017