Mulch is always welcome in the garden. Whether it is organic, mineral or made of plastic film, it will be chosen according to specific criteria.
What is a mulch?
A mulch is a layer of material spread on the ground that is useful in the garden. Mulch limits evaporation and keeps the soil cooler for longer, thus spacing out watering operations. It protects the roots from the cold, blocks the growth of undesirable weeds, limits erosion and can have an aesthetic function.
The various materials
Mulch can be made of various materials depending on its function or the desired effect:
Composed of organic matter collected from the garden (straw, grass clippings, dead leaves, RCW, etc.), this mulch allows the gardener to recycle waste and costs nothing. By decomposing, it produces a very fertile humus that will feed plants and stimulate the life present in the soil. It must be used in a layer of at least 20 cm to be effective against weeds and will be renewed quite often.
All kinds of mulches (flax, hemp, cereals…) are made of crushed plant stems that serve as good barriers against gastropods.
There are other plant mulches such as pine bark, which is widely used at the foot of roses or acid-loving plants (rhododendrons, camellias, azaleas, etc.) because it acidifies the soil somewhat. This mulch lasts several years, just like the one made of cocoa shells which is ornamental but a little more expensive.
Canvas or film mulch
Well known to strawberry growers, black plastic film covers the surface effectively, preventing weeds from growing while warming the soil. It is fairly inexpensive to purchase and lasts for several years, but it is not really the most ecological solution!
Woven fabrics are to be preferred because they are biodegradable in the long term. Made of flax, jute or coconut fibre, they allow to cover the soil for a long time without disturbing its life because they let water and air pass through.
Durable, mineral mulch does not decompose in the soil. It is very much used in decoration to create contrasts or atmospheres (Zen garden, rock garden, design…). Small white pebbles, crushed slate, or pozzolan will each bring their specific color and a different effect that can be adapted to the decor.
Mineral mulches also have another use that we don’t necessarily think about: they conserve and restore heat, which is ideal in rock gardens with cacti or plants that particularly like heat.
This type of mulch also protects the collar of fragile plants from rotting.
Which Mulch To Choose For My Garden?
Choosing the right mulch for your garden can help reduce water waste, increase plant growth, and protect your plants from pests and diseases. Choosing the wrong mulch can make these issues worse. To choose the best mulch for your garden, consider the type of plants you plan to grow, how much water it needs, and its effect on the surrounding natural landscape.
Mulches help reduce water waste by reducing evaporation from your plants’ roots. Most plants don’t need a completely waterproof layer; a light mulch will help increase plant growth and prevent root damage. Choosing a mulch with the same color as or complementary to the natural landscape reduces disturbance to that environment. Choosing a dark mulch reduces direct sunlight exposure and increases nighttime temperatures for plant survival. Darker-colored mulches—such as black or brown—can cool down daytime temperatures even more by absorbing sunlight. Choose a dark mulch when planting warm-weather or sun-loving plants since they will suffer more if their roots stay wet. Conversely, lighter-colored mulches —such as white or light gray — can warm up nighttime conditions by absorbing heat from cooler objects in the environment such as tree bark or asphalt pavement.
Choose a mulch that mimics the natural landscape to reduce water waste since artificial materials in nature decompose faster than vegetation does. Artificial materials such as plastic also break down slowly compared to vegetation over time. Choosing a dark green leafy mulch reduces light penetration into your soil from vegetation below and helps retain soil moisture in cool seasons by reducing transpiration rates of your plants’ leaves. Choose lighter colored leafy mulches in warmer climates where increased soil temperature speeds up decomposition of vegetation over time to create extrahumus in soil structures below your plants’ roots.
Choose a different type of plant every three years to reduce plant competition for water and nutrients caused by constant root contact with one species over time. Choose perennials instead of annuals since annuals do not survive well under continual shade caused by perennial grasses growing beneath them. With perennial grasses, shade-loving annuals die out sooner than their roots can compete with established perennials for nutrients in the soil below them. Choose non-invasive nonnative species of grasses when planting because they can create desirable ecological functions such as erosion control and habitat for beneficial insects and birds without having to fight existing native plant species first.
Choosing a suitable mulch helps gardeners avoid wasted water while promoting healthy plant growth and stability of soil structures below their roots in cool seasons or at night time when it is cooler than the air above ground level at that time of year. Darker-colored leafy mulches mimic natural landscapes by reducing light penetration into the ground from above ground vegetation during cooler nighttime periods of year where less evaporation occurs from plant roots beneath porous dark green leafy material at that time of year than during warmer daytime periods when there is more evaporation from plant leaves beneath these darker layers of earth above them at that time of year than under less porous material at that time of year .