Mowing and tilling and cover crops

White Rock Vineyards- organically farmed in Napa Valley. April 2010

Ever wonder why some vineyards mow the cover crops in their rows so closely in Spring? Or why some don't? Or only mow every other row? Or why some vineyards don't appear to have cover crops at all? Since moving to a wine-growing area, these are the types of questions that pop up in my head on a regular basis. 

The answer to the first question is well-covered in the blog for Amapola Creek Vineyards in Sonoma Valley. Their post last month on flail mowing in the vineyards does a great job in explaining how the mowing of cover crops in the rows just before bud break reduces the vines' competition for water. Their vineyards are organically farmed so the root network tends to be more spread out beneath the surface, and the cover crops can more easily affect their access to water. The mowed crops can also be a natural fertilizer. Furthermore mowing the cover crops closely in Spring can protect the vines from spring frost by allowing cold air to circulate near the ground rather than around the vine.

As to why every other row may contain a longer cover crop- the answers could be from providing space in the alternate rows to toss vines during winter pruning. They could then be mulched to provide nutrients to the soil. A good explanation of this process can be found at the StillwaterVineyards blog. It could also be a matter of two different cover cropping systems on alternate rows.

More and more vineyards are converting over to cover crops and minimal tilling of the soil as vineyard practices become more sustainable. Tilling reduces the vine’s competition for water and nutrients, and helps a new vineyard establish its roots. On the flipside it affects the structure of the soil and intervenes in the ecosystem of the vineyard.  Most of the vineyards that I see in the Sta. Rita Hills and Santa Ynez Valley are using a system of cover crops, although I saw a newly tilled vineyard the other day that piqued my thoughts on the subject.

I’ve highlighted links to information that I found useful. I’m just scratching the surface in the most general terms- I encourage any comments and/or clarifications. This is one of those subjects where questions and information begets more questions… Cheers!