Organic mulches are simply mulches made of organic matter. Not only do organic mulches have many of the same benefits as synthetic mulches including protection from erosion, weed suppression and root protection, they also add nutrients and humus to the soil as they decompose, improving the soil quality and its moisture-holding capacity.
Organic mulches provide benefits in both warm and cool seasons. In summer months organic much protects soil from foot traffic, heat and dry conditions. In cooler mid-spring months, organic mulches help to keep the soil from rapid warming and help maintain stable temperature and moisture levels. Ideally, it is best to apply mulch after good rainfall or after soaking the ground to prevent dry conditions.
Organic mulch is generally inexpensive and simple to apply. The following list identifies benefits and applications of some of the most common types of organic mulch.
Bark and wood chips are primarily used in landscape gardens to support the health of trees and shrubs. Wood chips are considered by many gardening experts to be the best type of landscape mulch because they are inexpensive, easy to apply and very effective in protecting roots, preventing weeds, moderating soil temperature and moisture, and as they decompose they improve soil quality.
Compost can be used as mulch and it is very effective fertilizer and a critical ingredient in maintaining healthy soil. However, compost does not prevent weed growth like wood chips and inorganic mulches. Compost is best used as a soil amendment rather than a mulch.
Grass clippings can be used as a fruit and vegetable garden mulch to prevent weeds and improve soil quality. Grass clippings should be applied in a thin 2-inch layer. If you notice a bad odor after applying grass clippings, you have applied too much and there is too much heat in the compost layer. Also be careful not to use grass clippings that have be exposed to herbicides and other toxins.
Hay or straw are both recommended for fruit and vegetable gardens and both provide good weed control. Hay and straw decompose quickly and improve the soil as they decay. Avoid using straw in extremely wet environments because rotting straw will attract slugs and other pests.
Leaves are among the best garden mulches because they provide good weed control and improve garden soil as they decompose. Leaves are inexpensive and available in practically every climate. Apply leaves in a 2 inch layer and if they become soggy and matted, mix in hay or straw. You can also shred leaves before applying them to prevent matting.
Newspaper can be used as mulch if it is covered with another organic mulch like straw to keep it in place. 2 to 4 layers of black and white newspaper can provide good weed control. Research has shown newspaper to be less effective than woodchips as mulch since it is more likely to attract termites and other pests. Also, the moisture of the newspaper must be more carefully moderated to prevent anaerobic (too wet) conditions that prevent water and gas exchange or hydrophobic (too dry) conditions that cause water to “sheet off” of the mulch instead of penetrating into the soil.
Pine needles last longer than other types of mulch like leaves and straw and they are a good mulch for landscape shrubs and trees. Pine needles are easy to apply and since they don’t compact, they easily allow water to filter into the soil.
Even though there are many important benefits to using both organic or synthetic mulches, there are also both correct and incorrect ways to apply and manage mulch. In our next post we’ll review some practices to avoid and discuss some tips to achieve the best garden environment for your plants.