How to Reduce Soil pH
(Increase Soil Acidity)
Alkaline soil is the term used for soils that have a pH level higher than 7.0. While some plants tolerate slightly alkaline soils (and some even thrive in them), most prefer neutral soils. This can present a need to reduce the garden soil’s pH level (increase the soil's acidity).
Soil that is too alkaline can cause plants to poorly absorb nutrients in the soil. While the nutrients may be in the soil still, the plants cannot adequately assimilate them in alkaline conditions. Just like with people, a lack of nutrition can lead to an unhealthy state for your garden. For alkaline soil, improve plant health by reducing soil pH and increasing the soil acidity to a more neutral pH range.
Generally speaking, apply the soil additive to your soil and rake it in to the top level of soil in your garden plot. (The majority of your plants roots will be near the top, so this is where they will be feeding most heavily from the soil). Thus, this is where you want the soil to be most compatible to the plant's needs.
Soil Additives to Reduce Soil pH
(Increase soil acidity)
Granular Sulfur / Elemental Sulfur
Granular Sulfur is the most common means of increasing soil acidity. It is often the most economical way of reducing soil pH, especially for larger garden plots. It is effective, but it takes a little while to see results. Allow at least 3 months before testing the soil again or applying additional sulfur.
Note: Different rates of application are required for different soil types. (Sandy soils require less, Clay soils require more.) Check with your local county extension office for recommended rates of disbursement for your locality.
Aluminum sulfate/Iron Sulfate
The sulfates react quickly to reduce the soil's pH level, but be cautious to not use too much and damage your plants.
Well-rotted Compost is always a premium soil enhancer for your garden. It neutralizes both acidic and alkaline soils, and supplies nutrients and necessary bacteria for the health of the garden.
If you have a ready supply of well-rotted compost, you can mix it into the overall gardening bed. If not, use it to improve the specific location (hole or row) that you're planting.
Sphagnum Peat Moss is an effective way to quickly reduce the soil pH level and increase acidity in your garden soil. Additionally, it will help break up the soil, retain water, and add organic matter to the soil. However, it can be expensive if you have a large area to affect. Sphagnum Peat Moss is available at most garden centers.
Pine needles can be used as a mulch in your landscaping. Only use them where you want to increase the soil acidity however.
Note: Pine needles release a chemical that can prevent seedlings from sprouting in your garden. With this in mind, you may want to limit the use to landscape mulching, or to areas of the garden where you don't plan to plant seeds directly into the soil.
Wood Chips or Shavings used as mulch in the garden or landscaping will also help reduce the soil pH over time.
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Note: the advice and information contained herein is based upon our experience and study. As with any advice, please apply at your own discretion.