Mulching and Irrigation

Mulch and irrigation are important components of any garden. When used effectively you can save a lot of time and money, by reducing the amount of water used in your garden.

Mulching your garden beds and around your trees helps to retain moisture within the soil

and reduces evaporation. The mulch reduces runoff when watering, allowing deep penetration of the water into the root zone.

Utilising Mulch

Reduction of Weed Growth

Humus

Beware: mulch gets hot

If the mulch layer is thickly applied (approx. 10 cm), most of the weeds are smothered. The few weeds which do germinate are easy to pull out through the mulch layer.

To Improve the Soil

As the mulch breaks down into organic material (humus), nutrients are released into the soil by micro-organisms and worms. The worms and micro-organisms consume the organic matter converting it to humus. The micro-organisms aerate the soil, providing a good environment for root growth under the mulch layer.

The humus improves the texture of sandy soils and can open up clay soils.

Mulch should be applied evenly over an area and not piled up around the trunk, as this can cause trunk rot or encourage pest and disease attack.

As the mulch is an active component of your garden it should be topped up every year to maintain the 10 cm thickness.

Please note that the mulch must be composted before applying on your garden, as thickly applied un-composted mulch gives off heat as it decomposes and may damage surface roots.

The best and cheapest type of mulch to use is “council mulch” made of street pruning and trees removed by the council. Pine mulch should not be used as it takes a long time to break down and draws out nutrients from the soil.

Also fertiliser is very important and can be added before applying the mulch.

Cover the whole root zone with mulch

Where to Mulch

90% of a tree's root system is in the first meter of soil. Depending on the species the feeder roots can spread over vast distances. Keeping this in mind the tree relies on the soil to be moist, weed free, within a certain temperature range, and provided with a constant slow release of nutrients. All of these requirements are provided by the mulch.

The mulch should be applied at least out to the drip zone, which is where the branches span out to. If this range cannot be achieved mulch whichever ground you can, for example garden beds surrounding the tree, or convert a lawned area into a mulched area.

Effective Tree Irrigation

In most cases watering your garden with a hose, sprinkler or sprays can prove ineffective in water retention within the soil, with exception to ferns and lawns. Most of the water applied by these methods evaporates. 75% of water can evaporate. With the use of mulch most of the water applied stays in the soil.

The most effective time to water is in the early mornings and evenings.

A more effective alternative is to leave a hose dripping or trickling on an area, for several hours, depending on the water use of plants in the garden bed e.g. are the plants trees or shrubs? Or if you have an irrigation system the sprays should be replaced with drippers. Both these methods allow for deep water penetration into the soil, for the plant’s roots to utilise.

Drippers allow the water to deeply penetrate the soil when compared to sprays.

With sprays the watering is shallow, the majority of water can evaporate before it can be utilised by the plant. When drippers are used, minimal water is applied to the foliage. The water will go to the plant’s root zone where it is effectively utilised.

The use of drippers is more effective when covered with mulch as it virtually eliminates evaporation.

To successfully irrigate trees in a sloping garden, apply the water at the top of the property, allowing the water to penetrate down the hill to the targeted tree roots.

Automating Your Irrigation System

A timer, manual or electric, can eliminate wasted water and damage to soil caused by hoses left running and forgotten sprinklers. Also as the water rates are now calculated on a user pays system, a timer is an inexpensive option. An electric timer can be set to start early in the morning when there is minimum loss of water due to evaporation.

Inexpensive water-saving option

The Tree Crew

Mulching and Irrigation

Suburbs