How to Mulch for a Healthy Garden

Why should I mulch?

Good question! There are actually four major reasons why you’re going to be mulching.

  • The first reason, and probably the most important reason for your Queensland garden, is water conservation. When you apply mulch to your garden, you stop the topsoil from drying out through evaporation. That means your soil is going to stay moist and you’re going to reduce the overall watering by as much as 60%! That’s a big plus for your water bill and means happier plants overall.
  • Secondly, mulching protects your plants from weeds and weed seed germination which can compete with your plants and trees for vital nutrients and water.
  • Thirdly, mulching works to keep the temperature of your soil constant which provides an optimum environment for growth.
  • Finally, when you mulch, you add organic matter to the soil which ensures extra nutrients for your plants and trees.

What kind of mulch should I use?

There are two types of mulch – organic or inorganic. We like organic mulches because they work to add organic matter to the soil, which as we mentioned above, adds nutrients. Organic matter also improves soil structure and drainage, encourages earthworms (always a good thing!) and improves the microbial activity of the soil.

Organic Mulch Types

Common mulches are pea straw, Lucerne and cane. Choose a bale, or buy the pre-chopped product if you would like a neater-looking garden. Both are just as effective

You can also source cube mulches, like cubed pea straw, and these will form a soft material when wet. While you can use these as mulch, they’re often better suited as soil conditioners and worked through your soil.

Bark mulches are another top organic option, and a great feature of these is that due to their harder nature, they take longer to break down and so you won’t be applying them as often.

You can choose from fine to coarse barks, but we recommend that you use a medium to coarse grade as they don’t absorb moisture, but let rain or watering through to penetrate the soil (where you want it). Using fine bark can be problematic as this kind of bark absorbs moisture and can also act as a proving ground for weeds.

Inorganic Mulch Types

When we say inorganic mulch, we mean things like gravel, river stones and scoria (an igneous rock with lots of bubble-like cavities). These kinds of mulches don’t break down and can look effective when used in things like pot plants. Be aware that using pebbles or stones as mulch on a garden bed may end up looking messy when littered by leaf matter and other garden debris, so you may be out there maintaining it. Not a reason to avoid it – we’re just mentioning it for your own awareness.

How much mulch do I use?

This all comes down to what kind of mulch you’re applying. If you’re running with a coarse bark mulch, you want to opt for a depth of between two and six centimetres. An unprocessed straw mulch can be applied thicker, but not more than ten centimetres as a guide.

Problems with improper mulching

  • If you have too much mulch applied to wet soil, you may find that there’s excess moisture in the roots of your plants which can stress the plant and eventually cause root rot. Too-thick mulch can also reduce air and water getting in, which is problematic for tree and plant health.
  • Don’t mulch right up to the trunk or stem of trees or plants as this can stress stem tissues and can lead to insect and disease problems.
  • Some mulches – especially fresh grass clippings – can cause pH problems which can lead to nutrient deficiencies. If you do want to use up your grass clippings, let them break down naturally in your compost first, and then apply them as a soil conditioner or improver – and then use a coarser mulch like straw or bark.
  • Natural decomposition of some woody materials, like un-composted fresh sawdust, woodchips and pine mark can cause nitrogen drawdown, whereby soluble nitrogen is taken from the mulch by fungi and bacteria. This can be combatted by applying a balanced fertiliser before you mulch.

What should I be mulching?

Except for a couple of plants that don’t like mulch – like the bearded iris – mulching is going to ensure a thriving garden with great water conservation.

We can help

If you would like some more information on mulching best practice or if you would like to find out more about our mulching services in Brisbane, get in touch on (07) 3264 6398 today. We hope this has been a helpful guide to mulching in your garden!

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