Understanding Mulches

The word on everyone's lips is "mulch" and it's absolutely essential because it can reduce water use by up to 70 per cent. It also suppresses weeds and weed-seed germination and insulates the soil. Some mulches are better than others and there are some mulching mistakes that people make. There are two basic types of mulch - inorganic mulches, such as pebbles and gravel - and organic-based mulches, such as pine bark, bales of pea straw, chopped pea straw, and sugar cane mulch. Organic-based mulches break down and add goodness to the soil. A favourite is baled pea straw. It is good because the bale can be broken apart into biscuits and these pieces are spread out on the ground. This means it doesn’t blow away and the birds won’t scatter it. When mulching with different straws or sugar cane it’s important to add at least five to seven centimetres for each layer to make it work effectively. But it needs replacing every year because it breaks down. Heavier mulches, such as pine bark or pebbles, need only be four to five centimetres deep. The mistake most people make is using compost - such as mushroom compost, garden compost or a cubed pea-straw-based product - as mulch. The problem with using these as mulch is that they are too fine and can absorb moisture. They allow moisture to be drawn out of the soil, through wicking, and they form a great weed seedbed, allowing for weed seed germination. Use these composting products as a soil improver or conditioner – they are fantastic for this - but top it off with a coarser product that doesn't absorb moisture. That way, you know you're doing your best for the garden, by conserving moisture, suppressing weeds and insulating your soil.