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Tips For Better Mulching

Seeing flowers bloom and other plants thrive is a rewarding experience for any gardener, hobbyist or otherwise. One trick of the trade that has helped countless gardens bloom and vegetable patches yield is mulching. Mulching is the act of adding an organic or non-organic layer over the soil. When done properly, it can help you get rid of weeds, retain the soil’s moisture and protect the roots from insects.

Types of Mulch

The first thing you need to know about mulches is that they are divided into two groups; organic and inorganic.

Generally speaking, inorganic mulch is replaced after one season. Some examples of inorganic mulch are glass, stones, pebbles, plastic, and polyethylene sheeting. This type of mulch helps prevent weeds from growing and stealing nutrients from your plants.

Organic mulch like sawdust, leaves, grass cuttings, straw, vegetable waste, manure, and peat, have to be renewed more often. While this sounds like more work, there’s an upside to organic mulches: it becomes fertiliser for the plants when it decomposes.

If you want to read more about the different varieties of mulches, check out our handy mulch guide here.

Before applying mulch

Clear old mulch

Since organic mulch needs to be replaced more often, inexperienced gardeners may make the mistake of layering a fresh batch of mulch on top of the older mulch. This can lead to compacting of the soil along with other complications that can affect the plant’s health. Whether you are using organic or inorganic mulch, the best practice is to remove some of the older mulch first before adding another layer. This also allows for the aeration of the roots.

Inspect for weeds

After clearing the last season’s mulch, inspect the garden bed for weeds. Some choose to apply herbicide two weeks before laying a new mulch. Doing this kills the weeds and makes it easier to pull them out.

Look for compacted soil

The next step is to look for parts of the garden bed with compacted soil. This shouldn’t be too hard to spot – signs of soil compaction include puddling after rain, stunted plant growth, thin and twisted roots, etc. Compacted soil can suffocate plant roots leading to poor health. Cultivate the soil using a rototiller or a hand cultivator.

Apply pre-emergent

Some people apply a pre-emergent to prevent weeds from growing in their mulch. If you choose to do this, apply the pre-emergent before and after the mulch is laid. The last step is to rake the surface to even it out. Raking gives you a neat-looking landscaping bed with zero lumps and the same level throughout.

Ideal height/thickness and frequency of application

Too much of anything is never good, that is why you should know just how much mulch you should lay. Overly thick mulch can cause plants to have shallow roots. And there’s also the danger of covering a plant’s roots entirely, making them rot and die. 75 mm or 3 inches of mulch is ideal for most settings. Another trick is to thin the mulch as you get closer to the root.

For smaller plants, about 2 inches or approximately 50 mm of organic mulch is enough. You can also follow the same rule when using inorganic mulches like peat gravel. Distribute the mulch evenly because the correct distribution allows the water to go to the root system more effectively. Once you achieve the right thickness of mulch, watering it a little would help keep it in place.

Ideally, mulch should only be applied twice a year. The first time should be in spring when it’s no longer too chilly. The second application should come in autumn because the plants will get the insulation it needs in the cold months.

What to avoid

Plastics and Geotextile

Many people use plastic or geotextile thinking inorganic mulch should be separated from the soil. However, instead of preventing the growth of weeds, what it does is cause water runoff. Not only that, it also doesn’t give the landscape bed a neat look especially, when the mulch shifts and the fabric is exposed.

Also, organic mulch works much better when it is in contact with the soil, so there is no need for a landscape fabric. In fact, the soil gets the nutrients it needs once it absorbs the mulch

Cheap mulch

Don’t be tempted to skimp on your mulch. Low-quality mulches can bring bugs, weed seeds, and traces of pesticide that would be costlier to treat. And for those who have pets, carefully read if the mulch you use isn’t harmful when ingested. It is very common for pets to digest small amounts of it when playing.


Properly set mulch need little maintenance. Usually, monthly inspections of the garden bed for soil compaction would suffice. If you spot any, use a rake or a claw to loosen the soil by scratching it. Go around the garden bed and do this a few times so you can be sure your plants get the right amount of water and there’s good air circulation for the roots.

You should also never delay removing fungus or weeds if you find them in your garden. Their presence means there is compaction in the soil and that the bed is already dehydrated. Cultivating and watering it takes care of this problem right away.

Need a hand with your mulching situation?

If you need a little helping hand in choosing the right mulch for your garden, give PBC Landscape Supplies a call on 07 55 981 377. PBC offers the widest variety of landscaping supplies, such as mulch, in the Gold Coast area to help you create your dream garden.