Using The Fall To Fix Soil pH

The ideal pH range for healthy growth of fruits and vegetables is 6.0-7.0, although there are a few exceptions with specific plants such as blueberries, which love acidic conditions. Nutrients become less available to your plants, even if abundant in the soil, if your pH is any higher or lower than this range. Continue on as our experts cover specific strategies for improving your soil’s pH, as well as some longer-term management practices to ensure it stays in the ideal range.

First we’d like to explain that soils with a pH below 6, which is too acidic, can be amended with lime, something we always keep in stock at A.W. Brown’s. Basic soil tests offer instructions for the amount of lime needed to fix your soil while soils that are too basic, above 7, aren’t quite as easy.

A high pH can be a result of several things:

• Some soils naturally have a high pH (or a low one)
• If your soil has excess compost, specifically composted manure, it may have a higher pH from the build-up of base cations
• High tunnels sometimes may increase in pH. Without adequate rain water to drive nutrients through the soil, they can build up, increasing soil alkalinity as well as pH.

We previously mentioned that adding lime to acidic soil to raise pH, and sulfur works in the opposite way—it lowers the pH of basic soil. This is one of the easiest and least labor-intensive ways to accomplish this, but it may take an annual or biannual repeat to maintain the lower pH.

The best plan of action? Add sulfur to your soil in the fall, and microbes in the soil will break it down into sulfuric acid. This doesn’t happen overnight, however, but by doing this in autumn, you can begin reducing pH before the next growing season.

Fruit crops are a little different, as it’s much easier to apply sulfur before planting than once the plants are actually established. Our experts recommend reaching the right pH the year before you plant, and from there on out only tweaking as needed.We recommend the following for reducing soil pH by one unit (e.g. from 7 to 6):

• Add 0.8 lb / 100 sq. feet, 8 lb / 1000 sq. feet, or 350 lb / acre in sand, loamy sand, and sandy loam soils.
• Add 2.4 lb / 100 sq. feet, 24 lb / 1000 sq. feet, or 1045 lb / acre in loam or silt loam soils.
• The lowering of pH in clay soils with sulfur is not recommended.
• Pine needles or coffee grounds should not be used to lower soil pH, as they are not effective. Coffee grounds aren’t all acidic, and even when they are, it would take massive amounts to change soil pH. Furthermore, you would need an unrealistic amount of pine needles to actually lower pH.
• Many resources recommend using sphagnum peat to rapidly lower soil pH for blueberries. While this can be effective, there are potential environmental ramifications. It is mined from a fragile ecosystem, and we urge you to consider using something different as peat bogs and fens are under increasing environmental threat!

To prevent your soil from becoming more basic, we recommend taking regular soil tests and tracking your results. Manure can also be a factor in increasing pH, so test that as well! If you’re using compost systems, try to mostly use vegetative compost as opposed to food scraps.

If you’re still struggling with your soil’s pH, we’re here to help. Come on down and speak with one of our lawn and garden experts, who would be happy to help you out and offer recommendations that fit your needs.