Do Grapevines Need Acid Soil?

Grapes and pH

• Grapevines grow very well in soil that is acidic, but not too acidic. The ideal pH range for grapevines is somewhere between 5.0 and 6.0, which is slightly to moderately acidic. Aluminum toxicity can be a problem in more acidic soil with a lower pH. If you are unsure of the pH of your soil, you can get a soil test kit from your nearest university extension office.

Raising pH

• If you have very acidic soil, liming is the easiest and most common way to raise its pH. Finely ground limestone or dolomite are the most frequently used liming materials; they are composed almost entirely of calcium carbonate, which raises pH by neutralizing acid. Alternative liming materials such as ground eggshells, oyster shells and wood ash can also be effective. Whatever form you choose, it should be finely ground and must be incorporated thoroughly into the soil to be effective. Your soil test results will indicate if lime is necessary and in what quantities.

Lowering pH

• Lowering pH is not as easy as raising it, but incorporating some form of sulfur into the soil is the most common solution. Aluminum sulfate and pure elemental sulfur are the two options open to most gardeners. Aluminum sulfate will lower the pH immediately, but elemental sulfur takes time --- sometimes a full season --- for bacteria to convert it to sulfuric acid. A third option is to incorporate acidic organic materials such as sphagnum and peat moss into the soil. These also take time to be effective, but may be less expensive than sulfur.

Other Considerations

• Soil acidity is not the only thing you must consider when you plant grapes. Grapes grow best in deep, sandy loam soils of moderate fertility. Avoid overusing fertilizers, as this can lead to large leafy vines that produce only a few small grapes. Drainage is also important: Look for soil that is moist but well-drained. Avoid planting grapes in an area where the soil becomes waterlogged or where pools of water gather after a rain.