Organic Mulch and Inorganic Mulch for Garden Mulching
Type of Organic Mulch
- Wood bark chippings make a decorative and long-lasting organic mulch. The large and relatively heavy particles don’t blow around in the wind and they counteract rain splash on to low plants.
- Garden compost, provided it is well rotted, can be used as a combined mulch and conditioner — as it decomposes further, nutrients and humus are mixed into the soil. Renew it every year.
- Stable manure should be well decayed otherwise it will scorch delicate roots and smell unpleasant. Don’t pile it up around the base of plants. Grass weed seeds may be mixed with the straw.
- Composted bark is used in much the same way as peat as an organic mulch and soil conditioner. It is good for acid-loving plants and its dark colour provides a good visual foil for decorative plants.
- Grass clippings can be used as a cheap organic mulch, but compost them first. Never use clippings from a lawn which has been treated with weedkiller and keep the mulch to a maximum 1cm (1/2in).
- Straw makes a soft open-textured organic mulch for and other low-growing soft fruit crops, helping to keep the ripening fruits clean. It is too obtrusive for use among ornamentals.
Types of Inorganic Mulch
- Tree spats can be bought from specialist suppliers. Made from bituminous felt, they are durable and easy to install.
- Black polythene (see below) is a good inorganic mulch for conserving soil moisture and suppressing weeds, especially around thirsty salad crops such as .
- Proprietary strawberry mats, made from synthetic whale-hide make a perfect inorganic mulch, and they keep the fruits clean and help to protect them from soil-borne pests.
- Stone chippings or coarse gravel make a natural-looking, free-draining inorganic mulch around alpines and keep the collars of the plants dry and rot-free.
Ground Cover Plants
Certain shallow-rooted, low-growing plants can themselves be used as a living mulch around the roots of large plants which like cool, moist roots. For example, gold creeping Jenny (Lysimachia nummularia ‘Aurea’) could help to provide the right cool soil conditions for a large-flowered clematis hybrid without competing significantly for water or nutrients, and would provide a very decorative feature in its own right.
Laying a Black Polythene Inorganic Mulch
1. Prepare the planting bed as usual. Then lay the polythene sheeting over the entire area, allowing a little overhang at the edges. Using a hand trowel, make a shallow trench all round the perimeter of the bed.
2. Tuck the edges of the polythene into the trench, then anchor them by infilling with soil. The surface of the polythene should be flat but not too taut. Don’t tread on the mulch — work at all times from the edges.
3. Using a sharp knife or scissors, cut crossed slits at the required spacings to act as planting and watering holes. Then dig planting holes in the soil below the slits using a hand trowel or bulb planter.
4. Insert young plants through the slits, firming them into the soil underneath the mulch. Water well through the slits and make sure that the polythene tongues are smoothed back around each plant stem.