Proper Land for Grapes

Soil Characteristics

• Grape vines need to develop a strong root system. They need loose soils that are about 3 to 4 feet deep to encourage the roots to grow deep and spread wide. Grape vines thrive in a sandy loam, meaning a mix of sand, clay, silt and organic matter, but they will also grow well in sandy or gravely soil. Grapes mature earlier in sandy soils because those soils warm up rapidly. Too much clay in a soil will form a crust in hot weather that will block water from penetrating to the roots. A good mixture of soil for grapes is about 20 percent clay, 35 percent silt and 45 percent sand. You want your vines to grow grapes, not foliage. If the nutrient level in your soil is too rich, your vines will produce a lot of foliage and not many grapes.

Soil Drainage

• Grape vines do not like soggy soil and standing water. Grape soils need to good drainage which is one reason why hillsides are choice locations for vineyards. If your area has heavy or prolonged rainfall, you need to plant your grapes on sloping ground.

Soil PH

• Soil pH measures whether a soil is acidic or alkaline; 0 is highly acidic, 7 is neutral, 14 is highly alkaline. The soil pH of your soil can affect the chemical form of nutrients that your grape vines need. A soil level between 6 and 6.5 is best for grape vines to absorb the nutrients they need for vigorous growth and high yields of grapes. If your soil is below 6 you may have to add lime. If your soil has a pH of 8 or higher, the yield of grapes will likely be poor, and you should add gypsum to the soil to lower the alkalinity.

Iron in Soil

• Soils with a reddish tint are usually high in iron. Grapes grown from soils that are rich in iron often produce wines with a slight cloudiness. This cloudiness is also called a ferric casse, which is difficult to get rid of without sophisticated equipment. Grapes grown in soil that is high in phosphorous will also produce wines that have a high iron content. High levels of boron in soils will produce early maturing grapes with a high sugar content.