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How To Do a pH Soil Test

Measuring You Soil’s pH

Mother Earth is not always ready to receive your plants, and soil pH and makeup can be the difference between success, mediocre results and failure in the garden. This is the first in a series of posts on soil, and how it is the most important growth factor for healthy plants in your garden and landscape.

What is pH?

Ah, pH brings back memories of high school and chemistry where I met my beautiful wife. Who knew it would be critical to my pastime and the flowers we grow for market here at Celtic Farm. So what is pH exactly? Well, the term pH in gardening and soil describes the relative alkalinity or acidity of your soil. For the geeks in the room (me!!), it’s a measure of the relative concentration of hydrogen ions within a solution, or in this case, your soil.. But what does soil pH have to do with plants in the garden? Essentially, soil pH affects how nutrients are dissolved in your dirt, and how readily available they are for your plants. The vast majority of the core nutrients required for a plant to function and grow come from your soil, and you can think of pH as an indicator of how available they are to the roots.

What soil pH range is acceptable?

Well, that depends. I hate that answer ;). For the most part, plants like a slightly acidic soil. The pH full range is 0.0 – 14.0 with lower values being more acidic, and 7 being neutral. The scale is exponential, so small changes in the scale number can mean a big difference. For most plants, 6.5-7.5 is a good range to shoot for, and will provide an environment for healthy plants of all types. There are some plants that require slightly acidic soil to prosper:

  • Hydrangeas
  • Azaleas
  • Daffodils
  • Camellias

How do you measure pH?

There are a number of ways to measure soil pH:

  • With a garden pH meter
  • With a garden soil test kit
  • With a home made test kit
  • Bring a sample to a local garden or farm store
Best Soil Meter for pH Testing
Our Simple Effective Soil pH Tester
(Shop Soil Meter Here)

We like to use a pH meter: simple, fast and no mess. Most of the meters on the market are fairly accurate, and can definitely show you quickly your soil pH and other key soil requirements. If you want to get really exact numbers, bring the sample in to your favorite garden shop and the master gardener there can help.

How do I fix soil pH?

Ok, so you test your soil, and oh no, it is out of the range. Here are some readily available amendments to help.

To raise your soil pH and make soil less acidic:

  • Wood ashes
  • Garden Lime

To lower your soil pH and make soil more acidic:

  • Aluminum sulfate (fast)
  • Sulfur (slow)

Add these incrementally and retest your soil pH until you hit your sweet spot.

Does soil pH change?

pH can vary depending on the location of your planting area, and should be checked monthly during the growing season. The following can have a dramatic affect on pH:

  • Heavy rain, flooding or overwatering
  • Application of fertilizer
  • Addition of decaying organic matter
  • Heavy existing root systems

A garden meter can be handy for frequent testing after any of these events or existing pH altering conditions.

Just a quick set of thoughts on pH and the garden. See the following reference links below for more info:

SUNY Soil pH Guide

Clemson CoOp Extension Soil pH Guide

UC Davis Soil Lab

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