Why are there piles of dirt around our grapevines?
Why are there piles of dirt around our grapevines?
Soon. after all the juice from the 2023 vineyards was in tanks and barrels – and before tractors were winterized for the season, winegrowers were busy out among the vines “hilling up” fresh dirt on the bases of their winter tender varieties. What is this about and why is this tedious task so important?
Winter injury is one of the primary limiting factors in vineyard management practices in Northern Ohio. Those who choose to grow vinifera [varieties like Chardonnay, Riesling, the Cabernets, the Pinots, and other Vitis Vinifera] almost always use grafted rootstock to ensure a quality, award-winning wine down the road.
Before the dreadful Polar Vortex winters of 2013-2014 and 2014-2015, few local growers protected the sensitive vinifera grafts with dirt. The result was near total devastation in most of the vineyards. Unlike spring frosts when a single harvest will be damaged or lost. When such severe temperatures like the -35 degrees Fahrenheit occurred, not only were single vintages lost for the coming season, but in many cases, the actual vines were killed to the ground, requiring a total replant. Most growers’ vines did not return to full production levels for 3 or four years.
And even among those few vines that survived the two winters, most had their grafts infected with a disease called Crown Gall. Crown Gall’s spores entered the fissures caused by the cold snap and grew slowly, often over several years, eventually restricting nutrients and water until the resulting strangulation and vine death. [This is the same principle early pioneers used when they “girdled” trees to clear paths for roads and open early agriculture enterprises in what once were virgin forests here.]
Hilling up is a difficult task. It can be done manually or with existing farm machinery adapted to perform needs tasks. Locals may re-configure a single plow, a disc harrow, or even a vegetable tiller to move slowly and mound up the soil. The major concern is to be sure the tractor operator works very carefully to not damage or even uproot a vine.
The idea is to create a pile of soil at least 3 or 4 inches above the graft. Sometimes it will take the vineyard worker two or three times along each row to achieve the needed height. And when necessary, if the piles of soil are inadequate, workers walk up and down the rows, hand shoveling extra soil where individual vines need it.
The entire process usually begins right after harvest before the ground is frozen and hopefully when it is not too soggy as clumping soil will not achieve the desired results.
THEN…In mid to late spring, when all severe temperatures are gone, the next steps make the fall’s hilling-UP process seem easy. Taking DOWN the hills requires much more time and care. A tractor with the adapted plow may be used to take away some of the soil, but because of concern about additional trunk damage [and Crown Gall infections in the coming winter], vineyard managers need to clear the grafts, one vine at a time, with a worker who can be very careful with a shovel.
While we are sipping our sparkler this New Year’s Eve, most of us can understand and appreciate the work that goes into planting, pruning, and picking of grapes when they are ripe. However, few know that every row of grapes demands at least 30 to 35 visits by a winegrower each year. Two of the more obscure tasks, yet critical tasks: hilling UP and hilling DOWN are not often mentioned.
Wine is Born in a Vineyard – and protecting those grafts is one of the important yet obtuse baby steps necessary before wines go into the bottles.
For additional information: dwinchell@OhioWines.org