Mulching is an essential element of a water-efficient garden. Mulching around plants saves water by reducing evaporation and run-off. Depending on the type of mulch, it limits weed growth and can improve soil conditions by adding nutrients. Mulching also protects plant roots from high temperatures.
Choose the right mulch
Mulch can be in the form of leaves and grass clippings, sawdust, rocks and gravel, straw, bark or woodchips. Organic mulch, which breaks down quickly, will need to be topped up several times a year, preferably in autumn and spring.
Coarse mulch, which allows water to infiltrate more easily, is good for reducing weeds and keeping soil cool, but it will not improve the soil’s texture as the mulch does not readily break down.
Mulch made of fine particles can improve the soil’s texture as it breaks down more easily; however, it is more prone to compaction so will need to be loosened regularly to ensure water penetration.
Prepare for success
For the best result, prepare the soil by removing weeds, raking or digging the surface and watering the remaining plants. Place a layer of newspaper over the soil to deter weed growth, but make sure it’s not too thick as it will reduce air supply to the soil.
Spread the mulch layer
The ideal thickness of the mulch layer depends on the particle size of the mulch material. If using large chunks, such as pine bark, a deeper layer (more than 5cm) is needed. Mulch made of fine particles is more prone to compaction so it should be applied in a thinner layer.
Be sure to keep the mulch about 6-7cm clear of plant stems or they may rot.
Watch for nitrogen deficiency
As organic mulch decomposes it can draw nitrogen from the soil. Watch your plants for signs of nitrogen deficiency (usually indicated by yellowing of the lower leaves) and use a nitrogen-rich fertiliser if needed.
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