Ever visited a winery and gazed at the neat and tidy areas free of weeds underneath the vines? I have bad news for you. Weed-free under-vine areas are almost always the result of herbicide sprays, applied early in the spring when the grass is growing but the vines are still dormant, and the most common spray is Round Up. (The only other alternative is labor-intensive hand-weeding underneath the vines on a nearly constant basis, and there are a few dedicated folks on the passionate end of the regenerative farming scale who do it, but it's rare indeed and, in our view, unnecessary anyhow.)
Maybe it goes without saying, but, as folks passionate about regenerative farming, we are dead set against using Round Up (or any chemical herbicide, pesticide, or fungicide) in the vineyard. The science on glyphosate, the active chemical in Round Up, is pretty clear: it seems to be a factor in the decline of pollinators, it compromises the diversity of the soil micro-biome, it is a probable carcinogen that shows up in the human food chain (including your wine), and it's effect on the human gut micro-biome makes it a public health hazard. It's made by a company who does other things we can't and don't support (we're also passionate about open-pollinated seed diversity, among other things), and, above all, we don't think an empty under-the-vine area is necessary or even a good idea from a winemaking perspective.
There are a couple of reasons why vineyard managers have wanted weed-free under-vine areas. Plants growing underneath the vines tend to keep the temperatures lower in the spring, increasing your risk of frost damage and shortening your growing season. In a cool-climate area like Vancouver Island, that is a real consideration. It's also due that taller plants under the vines in the summer tend to retain moisture and can increase your risk of fungal diseases like powdery mildew. We spend a lot of time worrying about powdery mildew (especially since, as I discuss in another post, we don't use synthetic fungicides either). You'll also hear sometimes that the grass competes with the grapevines, and that is true for young grape plants. We planted some of our Gamay Noir along a shared fence line, where we couldn't control the grass on the other side, and we did find that those plants struggled. When we bought the acres next door and cleared out the grass, the vines took off dramatically. So we can say from experience that you do need to keep the weeds down underneath new grapevines. After the plants are established and have sunk their roots in deep, however, we haven't found that grass underneath the rows makes a difference in terms of competition. Grape vines have deep roots when they are established. Grasses and most weeds have shallow roots and live in a different area of the soil structure. (And if you're getting weeds with deep roots, that's the soil giving you a big hint that you've got some nutritional and compaction issues and problems bigger than a couple of thistles).
So for us, in our vineyard, the goal is to keep the under-vine growth short in established vineyard blocks and to limit the growth in the first three or four years in new blocks. But we don't agree that Round Up is the right solution. Apart from the public health concerns about herbicides, what you get when you use Round Up is bare soil, and bare soil is both vulnerable to topsoil erosion (and when you stop to think that about 18 inches on average of topsoil over this planet is what feeds the world and stands between us and mass-starvation and then realize that we've lost 1/3 of the world's arable land since 1950, you begin to think topsoil erosion is a big deal). Bare or exposed soil (as with tilling) is also land, however, where the soil micro-biome is compromised. And the thing is that soil micro-biome affects how plants take up nutrients. It affects (just like the micro-biome in our bodies) immunity and resilience to disease pressure. Winemakers also know that what we think of and call "terroir" is an expression of soil micro-biome. Put really simply: the bacteria in the soil affects how wine tastes. That means as a winemaker my central concern is making sure not only the vines but the soil is healthy and diverse. That's great for the grapes, and it's also the central idea of regenerative farming (because "sustainability" and simply not causing further degradation is not going to be enough).
What's our solution? The first is that we are a no-till vineyard. We don't turn over the soil in between the rows after planting. We do sometimes hand weed underneath the youngest vines, but when we do we seed with perennial cover crops that we hope to leave in place and let flourish indefinitely. We've tried a couple of things, primarily nitrogen-fixing forage like white and yellow mustard and white and crimson clover, and we've come to the conclusion that crimson clover is a plant we definitely want to encourage. Unlike mustard, which we love for its beauty but which can grow a few feet high, crimson low to the ground (and also beautiful), so we bypass the issue of spring frost risks and under-canopy summer humidity. Its roots are shallow enough that we find it doesn't compete a great deal even with young vines. It's great at fixing nitrogen in the soil and building soil. Finally, our Black Welsh Mountain sheep (a conservation species) and our gaggle of Toulouse x Embden geese (who also contribute nitrogen and help keep the vegetation low in the vineyard early in the season) love it mixed with native wildflowers and grasses.
So what's you'll see at Parsell Vineyard is no brown vine rows. Brown is dead. We don't do wine made from dead soil. And we're just going to do out on a limb and say it: you don't want to drink something that comes from soil that's been doused with a probable carcinogen, do ya?