The Gordon Gnohm

Play along at home, read Future Farmer in The Braidwood Bugle every Wednesday. 

Mulch Pt 2

Mulches are many and varied. They all have different uses and benefits to explore.

Last week we covered feeder mulches, if you didn’t read it, check it here, to catch up before you read this article.

A simple way to revive a lacklustre tree is to clear competitive grasses and mulch it. If you have normal grasses around the trunk and drip line, then a super low mow will do the job. Water deeply, the night before, then heavily mulch (200mm+) from the trunk out to the drip line with woody feeder mulch. Newspaper underneath is a good addition or light cardboard, no colours. Saturate material thoroughly before mulching over. 

If you do suffer zombie grass, Couch must be dug out and sometimes sifting the soil is needed to get it all. Kikuyu can be suppressed by woollen carpet, no synthetic backing. Carpet shops often have offcuts available. The carpet will breakdown slowly, suppressing kikuyu for way longer than cardboard. The kikuyu will grow up the trunk and out the edges of the carpet so itll take some focus to keep it out of the mulch, until its starves of sunlight. Then it will become food for microbes.

I prefer to use CSG Canberra Organic Blend Mulch. It’s a mouthful, but I believe it’s the best woody mulch in the Region. Fruit trees respond to this treatment very well. The late Cedric Bryant turned me onto this mulch when we worked together back in the summer of 2006/7 and Ive never looked back.

Let’s cover some other mulches.

Decorative Mulch 

Coloured Woodchips

A truly decorative mulch, and an expensive trap to avoid. The only benefit is to look ‘pretty’. The colour will last a short time until it eventually greys off like all woodchips. Sometimes the colour runs out when it gets rained on for the first time, perhaps into pourous travertine pavers. Putting down mulch takes time and effort so you might as well put down mulch that benefits your soil.

Protective Mulch 


Winter and summer can be tough on highland soils, so always top cover with the number one protective mulch for your vegetable garden. If you only use one mulch in your garden, make it sugar cane mulch. Put it on thick. 100mm minimum. When it settles, any area that is less than 50mm will expose the soil underneath, so put it on it thick. A thick layer will keep your active soil warm all winter and limit frost impact. Surprising growth from winter veggies can be witnessed. The mulch cover will advance early spring in your soil and in summer it will keep your soil cooler and reduce waterloss. 

Raw Woodchips

A favourite mulch for large garden spaces. They break down very slowly, I like to use them on paths, fresh is best when it comes to wood chips. The great thing about fresh wood chips is they steal nitrogen from the surrounding area as they start the composting process. This makes it difficult for weeds and grass to grow. The paths are maintenance free for 5-7 years only needing a top up as they settle.

This deep bed of woodchips eventually hosts the fungal network, who convert nitrogens into the kind required by veggies, fruit and berries rather than grasses and weeds.


A super protective mulch that wont break down, great for using over dirt areas and carparks, not so good for covering soil in garden beds. Pebbles are a nuisance to clean if you have falling leaves or windblown debris in the area, but they do have some benefits you might not be aware of.

What they can offer is a little boost to thermal mass in the area as Pebbles soak up the ambient temp before releasing the heat at night, but only a small amount. 

Round pebbles tend not to pack down very well, so they provide better drainage than crushed pebble. The gaps between the rounds accommodate air and water. Crushed pebble tessellates and packs well under pressure. This reduces settling in high traffic areas like driveways. The sensation of walking on both surfaces is different, providing textural experiences underfoot around your garden.

Choosing the right mulch for the application is about understanding. You can design long term function into your garden as you begin to understand, and stacking these elements will translate into a better Backyard Ecosystem. 

This week

One of my tomatoes has just popped its first flower!! 

In the ground Pumpkins and Zucchini. Button Squash are ready but theres no room in the garden. A tomato was eaten down by the chickens and the resprout is taking too long, (probably because Im watching intently) so I replanted next to it to see who gets up first. 

Theres a cold front coming in this weekend, but with weeks of growth and plenty of cold nights, my tomatoes will survive. Its much easier to box a 30cm high seedling from the last frost now than protect a whole mess of ripening tomatoes from the first frost in autumn. 

The Catalpa has got its leaf on this week, and the Kunzea hedge in the garden is full bloom. The Kunzea outside the garden fence is not, so the microclimate we have created inside the garden is doing wonders. Cherry blossoms have departed and tiny cherries are hanging on the branches.


The flies are starting to be annoying enough to think about setting up stinky fly traps around the perimeter, but it feels well too early. The first mosquito was seen at the window screen last night, on the outside thankfully. The carnivorous plants in the kitchen are getting a good spring feed. The Venus Fly Traps are catching plenty and the Nepthenes are recovering well after the winter transplant. Outside in the garden the Sarracenias are putting on flowers and will sprout new pitchers shortly, so ill be trimming off the old ones to make way for the new. 

And the sounds of microbats now fill the night air as they use their sonar to hunt mosquitoes. The microbat population dropped dramatically after the fires but they are slowly building up again. 

Red browed finch pair spotted in the garden this week, and there is a new resident to the main dam. A white throated heron. Its big, really big, and the feathers are immaculate, so im guessing a juvenile finding new territory. Hes been here for weeks. Resident water birds are rare on our hill, so its an exciting change.

Next week Mulches to Avoid

Stay awesome

The Gordon Gnohm

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