Spring Greening  - March, 2010
 

 
Spring is a lovely time of year anywhere, and in Napa Valley, the beautiful fields of spring flowers aren't just for looks.  The vibrant yellow blossoms of mustard not only add color to a gray winter landscape but are adding nutrients to the soil and inhibiting weed growth!  Cover crops planted between the rows and around the vineyards provide a multitude of influences on the vine, the grapes they grow, and ultimately, on the wine.

Cover crops, also known as green manure, reduce water run-off and erosion, break up hard soils with sturdy root systems, reduce the need for chemical herbicides, pesticides and fertilizers, and even make it easier to get around the vineyards in wet weather.

They can help reduce vigor by using up excess water, nutrients and minerals in the soil that would otherwide unbalance a vine's growth.  In Rutherford, where the soils are alluvial and loamy, we like to use sudangrass, which is fast-growing and thirsty, to slow down the rate of vine growth.  This makes the vine work harder for the resources of the soil and put more energy into growing grapes, rather than leaves.  Up in the rocky soils of Howell Mountain we want to add, rather than subtract.  There, clover produces nitrogen and bulky, stemmy peas and alfalfa are tilled into the soil to increase organic matter and improve the texture, retaining soil that could otherwise wash away during winter rains. 

Certain plants will attract and harbor beneficial insects like ladybugs and lacewings, who can keep a vine free of aphids and will stick around to live in the vetch and prarie sunflowers planted between the rows.  Other plants repel instead of attract.  In our Dos Olivos and Manly Lane vineyards we use a mix of mustards, daikon radish and other brassicas that actually fend off nematodes, tiny bugs that can kill a vine by chewing up its roots and can spread diseases. 

So, if you are enjoying spring in Napa Valley, take a moment to stop and smell the mustard or clover.  These hardworking plants are a vital part of our plan to make the wines you love! 

Read the the rest of our March wine club newsletter here. >>


 

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