Compost pH Levels
pH is the chemical measure of acidity(sourness) or alkalinity(sweetness).
A neutral pH level is 7.0. The pH scale is a range from 0 to 14. 0 is highly
acidic, while 14 is highly alkaline.
Garden soil has a pH, and varies by type of soil and what is in it. Like
your garden soil, compost has a pH level. This level will also vary, depending
upon what you put into your composter. Early in the decomposition process,
compost tends to be acidic.
The ideal pH for most plants, is at or near the midpoint: 6.5 - 7.0 If compost
or soil is too acidic, or too alkaline, plants can not grow.
A wide variety of materials goes into composters. The contents often vary
from batch to batch. Most (but not all) plants and weeds have a pH near or
slightly below 7. Other compostable items can vary widely. So, it's important
for you to have some knowledge of the pH value of items your place in your
composter, and ultimately into your garden soil.
Do not adjust the compost pH, until it is finished decomposing. After your
compost has decomposed, and before you mix it onto your garden, we recommend
a quick home soil test for ph levels. See
Electronic Soil Testers
For more information, see: Soil pH
Prior to using your fresh compost, you can adjust the pH level. Add a little
wood ash, or ground limestone to acidic compost. To lower alkaline levels,
you can use sphagnum peat, elemental sulfur, aluminum sulfate, or iron sulfate.
All about Composting
Find Ideal pH levels for a wide range of flowers,
vegetables and herbs.