If you're looking to improve the quality of your soil, one of the first things you'll want to do is determine its pH level. Soil that's too acidic or too alkaline can prevent your plants from properly uptaking nutrients from the ground, which in turn leads to stunted growth and poor crop production. For instance, soil with an unbalanced pH level might not provide enough calcium for your plants to absorb and lead to blossom-end rot. Luckily, achieving an ideal pH is a relatively inexact science. While you will need to get the pH to fall within a specific range, it'll be large enough to allow you a little bit of wiggle room. Learning about pH and the process of replenishing your soil will help you create the perfect planting space for a wide variety of plants.

What is pH?

pH strips

pH is an abbreviation used in chemistry to gauge a substance's "potential for hydrogen." Don't be fooled by the strange capitalization — it isn’t an error. It's simply used to distinguish "Hydrogen," which is capitalized because it's an element on the periodic table, from "potential," which is clearly not an element. Basically, pH determines the amount of hydrogen ion activity occurring in your soil at the microscopic level. Alkaline soil contains a low amount of hydrogen ions, while acidic soil holds an overabundance of them.

Ideal pH and Nutrients

Different pH levels prevent different sets of nutrients from diffusing into the soil when water is added to it. Subsequently, nearby root systems are unable to access the nutrients they need to nourish their respective plants. Deprived of proper nutrition, the plants become more susceptible to illness and have a hard time growing any bigger. To create the best possible gardening environment, you'll want to get your soil's pH between 6 and 7.5. When the pH falls below 6, the soil will begin holding potassium, nitrogen, and phosphorus molecules captive. When the level exceeds 7.5, you'll find that your plants will struggle to get enough phosphorus, iron, and manganese.

In many cases, your soil’s pH will depend on your geographic location. For instance, the Pacific Northwest is known for its slightly acidic earth (below 6), while the soil in the Midwest tends to be a little more neutral. However, the construction of your home and your use of amendments may have brought in some dirt and nutrients from other areas. For this reason, it’s a good idea to test your soil to get as accurate of a pH reading as possible.

Testing pH

soil testing

There are two different methods of testing available to you. You can choose to buy a DIY test from your local gardening store, or you can have your soil analyzed in a professional lab. DIY tests can be a great way to determine your soil's general pH level, but they can sometimes be a bit inaccurate, especially if you're not careful to follow the directions printed on their packages. Theses tests come in the form of portable meters or kits that require you to mix water in with some soil before inserting a pH strip into the solution. To run a lab test, you'll usually have to gather soil from several areas in your garden and ship or personally deliver the samples to the facility of your choice. Part of the report that gets sent back to you will detail your soil's pH level.

Acidic Soil

If it turns out your soil is too acidic, you’ll need to work some alkaline materials into it to achieve a neutral pH. This is called liming, and it usually calls for the use of ground limestone. Most people prefer calcitic limestone, which contains calcium carbonate, though some will opt for dolomitic limestone when their soil is also experiencing a deficiency in magnesium. These compounds break down slowly, so you'll want to apply them in the fall to prepare your garden for the next growing season.

Alkaline Soil

shredded leaves placed over alkaline soil

If your soil is too alkaline, on the other hand, you’ll need to add some acidic materials to it. Elemental sulfur is often used to add some acidity to the soil, though shredded leaves and peat moss will also help you lower its pH. Keep in mind that some peat moss manufacturers are still using unsustainable production methods, which has led many gardeners to abandon the product altogether in favor of more environmentally friendly materials.

Gardeners that never cared for chemistry might find that their eyes start to glaze over at even the slightest mention of pH, but the good news is that it’s not an overly-technical concept. Getting your soil in the ideal pH range will give your plants the opportunity to absorb all the nutrients they need and produce a bountiful harvest for you to enjoy.