|A sample of vermiculite. Photo credit: Brian Pettinger Flickr CC BY-NC-SA 2.0|
Improving water retention in soils begins with understanding the soil type found in the garden. Soils are generally made up of varying mixtures of three sizes of soil particles; sand, silt and clay, known as soil texture.
Generally, water retention is inversely related to permeability. Sandy soils have the lowest water retention, followed by silt, and then soils high in clay.
Various soil amendments are available that can improve water retention, particularly soil high in sand.
Organic Soil Amendments
- Sphagnum peat moss (please note that Sphagnum peat may not be a sustainably harvested amendment)
- Coir dust (a byproduct of coconut harvest)
- Aged manure (may have high salt content)
- Other organic materials such as grass clippings and straw
- Vermiculite (expensive and breaks down quickly, better for container gardening)
- Perlite (excellent for container gardening)
These are some of the common and more readily available soil amendments for improving water retention. Each has its own unique benefits as well as limitations.
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