Soil Ph

By   October 8, 2015

Inexpensive soil testing kits are available at most garden shops and state agricultural extension offices. Theoretically, they can tell you exactly how much of each nutrient that you need to add and when to add it.

Even without a test, I can tell you with 95% certainty what you need here in the Northeast. Since Nitrogen is water soluble and gets consumed quickly in a lawn, chances are very high that unless you have fertilized in the last few weeks, your lawn needs lots of Nitrogen. Phosphate and Potassium don’t get used up as quickly, but established lawns have usually used up most of the supply.

Ph is Important

The test that is important, though, is pH. Here’s where you get to throw around technical terms and act like a scientist. pH is an abbreviation for the potential of hydrogen, or simply a measurement of the amount of acidity or alkalinity in a substance. It’s important because everything that goes on inside the cells of grass plants is chemistry based, and some chemicals just don’t work right if things don’t have the right amount of acid.

Without getting too technical, pH is measured from 0 to 14, with 0 being the ultimate alkaline level, 14 is the strongest acid, and neutral is in the middle at 7. Not surprisingly, grass likes it best around soil Ph of 7.

Here in New England, our combination of soil type, water, and our types of trees make everything acid. Fortunately, there’s an easy and inexpensive way to fix your soil’s pH. It’s the equivalent of giving your lawn a big Tums…ground up Limestone is available from most garden shops and discount stores. It goes on easily, starts working quickly, and lasts a long time.

The bad news is that it sometimes takes a lot of limestone to correct neglected soil, it may take a while to penetrate down to the lower levels of your lawn’s roots, and needs to be reapplied every few years.

Limestone is generally available in two forms, ground to a powder and pelletized. The ground limestone is the least expensive and, up until a few years ago, was the most popular. It’s a fine powder and needs to be applied with a drop-type spreader. Many a gardener has found that, as they work up a sweat pushing the spreader, the fine powder that blows around sticks to their moist skin and they end up looking something like Casper the ghost.

Pelletized limestone eliminates this problem. It’s formed into small pellets that spread easier, don’t blow around, and can be applied much quicker with a broadcast spreader.

An important note…limestone is generally safe. After all, it’s added to food as a source of calcium, but it’s never good to expose your skin to large amounts of the low pH material, and getting the dust in your eyes or nose can cause irritation.

High Ph

It’s unusual but some in some locations the soil might be too alkaline, the opposite problem that most of us face.  It’s unusual in the major grass growing zones, so if you soil tests as heavily alkaline retest to be sure.  Some plants and shrubs like their Ph to be heavily acid.  Blueberries are the most common acid lovers although many of the evergreen foundation plants will prefer slight acid.  Hydrangeas will tell you if they need more acid.  Above Ph 5.5 soil Ph or so and their flowers will be pink, below 5.5 and the flowers are blue. Aluminum sulfate is the most common chemical used to bring the Soil Ph down.