Mulching Benefits / Organic and Inorganic Mulch Types

Category: Gardening Articles | Posted: Fri Dec 02, 2005 1:09 pm

Mulching is the practice of placing a loose surface onto the surface of soil in your flower or vegetable garden in order to protect, insulate and beautify the area. This loose covering is called a mulch and it can be either of an organic or inorganic variety. Examples of mulches include compost, stone and grass clippings. Every gardener should understand the many benefits of mulching the soil in their garden. This article will discuss the benefits of mulching, how to choose the correct mulch and have a quick look at some of the different types of organic and inorganic mulches available.

Benefits of Mulching

Let us explore some benefits of mulching:

Prevents soil erosion - Soil erosion happens when winds or water slowly wear away the surface of soil and remove it. Mulching your soil will prevent this as there is now a protective, replaceable layer.that comes between the surface of the soil and the forces of nature above it.

Insulates the soil in winter - The harsh temperatures of winter can be unkind. Mulching the soil in winter will insulate the soil preventing it from repeated patterns of freezing and thawing and will insulate plant roots. It prevents heaving (buckling upward) of soil in spring. Mulch should be applied to the soil when it has frozen and removed in spring only when there is no danger of further frosts. Winter-mulched soil thaws out more quickly in the spring.

Cools down soil in summer - A layer of mulch in summer protects the soil beneath from the extreme heats of summer and reduces the need for constant watering i.e. water retention is improved.

Helps against soil compaction - The layer of mulch acts as a buffer or extra layer between entities that can cause compaction on the soil below e.g. people, equipment, heavy rains.

Improves appearance - A mulch applied to your bed can make it look more complete and attractive. This varies from mulch to mulch as some are more attractive and natural looking than others.

Prevents weed growth - One of the more useful benefits of mulching is in weed prevention. While the mulch itself will not stop weeds from germinating it serves to act as a barrier between the weeds and the outside world above. When a weed reaches the mulch layer it will not be able to break above it and it will eventually die back. Some mulches perform this weed prevention feature better than others. Depth of mulch is also a contributing factor. Care should be taken however when selecting mulches as some mulches like grass clippings and straw may actually contain weed seeds.

Keeps fruit and vegetables clean - A layer of mulch reduces the chances of fruit and vegetables getting dirty from splashes from the soil below.

Choosing the Correct Mulch for Your Garden

Careful thought should be given when choosing a mulch to apply to your garden as each is different and should fit in with your exact requirements. Here are some common factors that should be considered:

Soil pH suitability - Some mulches like bark mulch and pine needle mulch can affect the pH value of soil so they are best used on soils containing acid-loving plants.

Removal in spring - Certain mulches need to be removed in spring because they can smother emerging plants. Examples include stone mulch and bark chips.

Cost - Is cost a limiting factor in your choice of mulches? If so you can find your mulch for free if you choose certain types. If you keep a compost heap then you will have compost for mulching. Other free mulches (if you have the sources) are pine needles and grass clippings.

Appearance - Do you care about how the bed will look when the mulch is applied? Each mulch adds a different look and depending on the design of your garden you may want to choose a mulch that matches it in colour and texture.

Penetration by water and air - Some mulches are better at allowing water and air to pass through them than others. This may be important depending on a plant's watering requirements.

Addition of nutrients to the soil - Organic mulches add nutrients back into the soil when they decompose. The nutrient types and their amounts added back into the soil depend on the mulch and it varies quite a bit. Using compost as a mulch guarantees plenty of nutrients for your plants.

Some Types of Organic Mulch

This type of mulch once used to be living material and as such will decompose over time. During their decomposition vital nutrients will be added back into your soil. However you may want to avoid using organic mulches if you have rodent problems. Some common organic mulches are:

Compost - Mulches and feeds the soils as it decomposes. This mulch is free if you have access to your own compost heap. Apply at a depth of 1 - 3 inches.

Pine Needles - Commonly used with acid soils. Cheap, looks great and allows water to pass through freely to the soil below. It decomposes quite slowly however. Apply to a depth of 1 - 1.5 inches

Straw - Provides great insulation, water penetration and weed control. Care should be taken that straw does not contain weed seeds itself. Apply to a depth of 6 - 8 inches.

Grass Clippings - Readily available and decomposes quite quickly adding nitrogen back into the soil. Try not to apply too fresh as it can heat up quite a bit and possibly cause damage to your plants. Apply to a depth of 1 inch.

Newspaper - Provides great weed control and is readily available. Apply another mulch on top to keep it in place. Apply in 2 layer sections.

Some Types of Inorganic Mulch

Inorganic mulches are inert materials that have not originated from living material. Sometimes inorganic and organic mulches are used in conjunction with one another. For example a geotextile (inorganic mulch) may be covered and held in place by bark chips (organic mulch). Some common inorganic mulches are:

Stone - Looks great and provides great insulation. If removal in spring is a factor in your choice of mulch avoid using stone. Degrades very, very slowly. Apply to a depth of 2 - 4 inches.

Plastic - Does not decompose so it does not add anything into the soil. Acts as a great weed control and is easily laid. Must be perforated to allow water to pass through. Apply in a thickness of 1 - 6 mm.

Geotextile - Expensive blanket-like synthetic fiber that provides great weed control and allows for water penetration. Almost always used in conjunction with a cover mulch (e.g. bark chips). Apply in a single layer.

Conclusion

In this article we looked at the many benefits of mulching and the different types available. Maybe take the time today to decide which mulch to use in your garden if you have not mulched in the past. You may be surprised at how cheap the process can be if you use mulches such as compost from your compost heap, grass clippings from your lawn cuttings and/or the Sunday newspapers! Happy mulching.

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