What is pH Levels in Potting Mixes for Optimal Plant Health
Canadian tap water and your potting mix. Canadian municipal water pH varies significantly by region. Coastal BC and most of the southwestern Prairies sit in the alkaline range (pH 7.5-8.2) because of limestone and glacial bedrock. The Maritimes and parts of the Canadian Shield run slightly lower because of granite. If your potting mix targets a slightly acidic pH (6.0-6.5) for aroids and tropicals, the higher-pH tap water in many Canadian regions will gradually push the mix alkaline over months of watering. Tropical-mix users in alkaline-water cities may want to acidify their water with a quarter-teaspoon of white vinegar per gallon every third watering, or use collected rainwater during the warmer months.
pH, a term frequently mentioned in discussions about potting mixes and plant health, is a measure of the acidity or alkalinity in a given potting medium, but what exactly does it mean? Simply put - pH is the measure of acidity or alkalinity in a given potting medium. Why is measuring pH important? Because a plant’s ability to absorb nutrients depends on the pH level of the medium it's potted in! If pH levels are off, it won’t matter how many nutrients are in the potting mix…the plant won’t be able to absorb them. So, what are the ideal pH levels for our potting mediums?
- Nutrients are most available to plants when the pH level is around 6.0 (the measurement scale is 0-14)
- So anything between 5.5 and 6.5 is usually good.
- Potting mediums are considered to be acidic as pH levels drop below 7.0 and alkaline as pH levels rise above 7.0.
Plants generally prefer a slightly more acidic potting medium which increases a plant’s ability to absorb nutrients. If you want to test the pH of your potting medium, there are lots of home testing kits online which you can use, and the tests are easy to do, so don’t be intimidated 🙂!
