Here’s all you need to know about this cost-effective protection for your plants – and how to put it to work in your garden.
By Life is a Garden
home July 2011
Mulch is any substance that can be placed on the surface of the soil around plants in order to keep moisture in the soil. It’s one of the quickest, easiest and most cost-effective ways to save water in your garden. There are two types of mulch: organic and inorganic.
Organic mulches come from plant and animal sources. Examples are compost, grass cuttings, pine needles, bark chips, bark nuggets, straw (not hay as there are too many weed seeds), strawy manure, crushed mealie cobs, fruit pips, nut shells, autumn leaves and shredded newspaper. Organic mulches are best because, in time, they break down and enrich the soil – and earthworms help with this process.
Inorganic mulches are substances or materials that don’t break down and enrich the soil, but nevertheless help retain moisture. Examples are gravel, pebbles and stones.
Mulch at work
• Mulch lowers the temperature of the soil, so less water is lost to evaporation.
• It reduces exposure to wind, which results in less moisture loss through evaporation.
• It promotes good root growth by retaining moisture in the root zone.
• It suppresses weed growth by keeping out the light.
• It prevents soil being washed away from around plants during heavy rainstorms by softening the impact of the falling water and slowing it down so that it can soak into the soil before running off.
• It functions as protection in cold climates, preventing frost damage to plant roots.
• It requires no watering, whereas groundcovers and lawn do. All water is therefore available for nearby plants. In dry regions, a mulched area around trees and large shrubs is more practical and waterwise than lawn or groundcovers.
• Organic mulch eventually breaks down and improves the quality and water-holding capacity of soil near the surface.
• Organic mulches attract useful microorganisms and earthworms.
• Soils with organic mulch do not need digging as microorganisms do all the work.
Low-growing groundcovers can also be used as mulch. Position them according to growing needs, such as tolerant plants for shady areas, etc. For the greatest conservation of water, select low water-usage groundcovers.
Some examples are:
For sun Aptenia, vygies, echeveria, seaside daisy (Erigeron karvinskianus), gazania, dymondia, trailing osteospermum, wild garlic. For shade Agapanthus, hen- and-chicken, variegated plectranthus.
How to mulch • Before applying mulch, hoe the ground lightly to improve ventilation. • Make the mulch thicker during very dry, hot or cold weather. • Never mulch in beds planted up with seeds that need to germinate. Only mulch the soil after the seeds have grown. • In spring, after the last frost, pull back mulch from emerging bulbs and perennials. • Leave a space between the mulch and the trunks and stems of trees and shrubs. REMEMBER Sandy soils need a thicker layer of mulch than clay soils.