Using Weeds to Grow Better Wine | June 2017

For the last five or ten years I’ve been nurturing a succession of native cover crops growing under my vines. The results have been encouraging. Even after all this time I still feel that I’m going through a long learning curve, but I would like to share my experiences.

My relationship with the ground under the vines has been somewhat tumultuous. In the 1980s the grape hoe was the method of choice. Farmers love to cultivate and I was no exception. Weeds were buried by hilling up, then later skillfully, meticulously, and melodically those mounds were taken down with what looked like a miniature snow blade mounted on the side of the tractor. One needed a strong back for the additional handwork required to hoe around each trunk. Time, labor, and erosion became problematic.

In the 1990s we started planting to the Lyre training system, which made it logistically impossible to use the grape hoe. I’m not proud of this second phase of weed control, which involved copious amounts of herbicides, both pre-emergent and contact. It is challenging to control the weeds under the relatively wide swath of the horizontally divided Lyre training system. Under the trellis was kept totally free of weeds. Vine vigor responded. We responded to vine vigor spending a lot more time with canopy management. Fungus diseases became more of an issue and the red wines developed some bell pepper characteristics.  This wasn’t too successful.

In the early 2000s we started experimenting with sowing low growing cover crops. Creeping Red Fescue (CRF) became an instant favorite and was sown under just about every vine. Competition slowed vine growth to a manageable level. The red wines lost much of their vegetative qualities. We could also significantly reduce our fungicides sprays. However as the vines got older there was a drop in vigor to the point where trellises could not be filled, leaves were yellowing, and yields were falling. White wines lacked the vibrancy and minerality of earlier vintages. The pendulum had swung in the other direction.

Around this time a French winegrower visited. He asked why I hadn’t considered encouraging what was already well adapted to our environment: weeds. Since that day I have taken a keen interest in weeds. But weeds are not weeds if they are desirable. Native cover crops (NCC) is a longer, but more correct and sexier term. Most of Hardscrabble is now managed using a sequence of native cover crops. None of these have been sown. All are volunteers that have been encouraged by sparing and persistent early morning spot backpack applications of glyphosate (aka Roundup) at targeted non-desirable weed species. If nothing else, I have now become much more aware of all the plant species growing on my farm.

Examples would be two of my favorite NCCs: chickweed and black medic. Chickweed crowds out most early season weeds and forms natural mulch in April. In May it goes to seed and dies, not to be seen again until next late winter. Around this time black medic, a low growing legume similar to clover or alfalfa starts to grow. It forms a thick carpet of bright green foliage and yellow flowers.  Again, it will smother out most competing weeds. While chickweed is basically non-competitive to established vines, black medic can slow down vine growth and vigor. Both of these plants self reseed easily.

In newly planted ’baby’ vineyards NCC competition is discouraged until August. Conversely, mature vines with higher water holding capacity can handle constant competition. I’m learning how to fine-tune the cover crop competition in relationship with vine performance and the vintage. Now that we plant steeper slopes, NCC can essentially prevent erosion. Bio diversity flourishes. Herbicide use has been greatly reduced, but not eliminated at this point.

While there will always be the potential for unintended consequences in the long term, I’m feeling more and more confident about using weeds to help make better wine.

Grape Press, June 2017

Jim Law