Too Much Mulch?

“I think of marriage as a garden. You have to tend to it. Respect it, take care of it, feed it. Make sure everyone is getting the right amount of, um, sunlight.” ~ Mark Ruffalo 

At every garden show, almost every article and TV segment I have seen, all extol the miracle of mulch.

Spread it around!

About 10cm thick!  

Do it! Do it! Do it!

So, I did.

Nasturtiums sprawling under my mandarin tree.

Nasturtiums sprawling under my mandarin tree.

Pea hay, shredded sugarcane, sheep poo and layers of newspaper have all been dutifully laid on my water-repellent sandy soil in a desperate attempt to keep water evaporating away from my precious plants.  It did a great job of keeping any weeds away too.

But, after a few seasons of this heavy mulching, I realised that something weird was happening.

The mulch appeared to be making my soil even more water repellent.  It wasn’t keeping the water in.

It was keeping the water out.

This was evident to me after a thunderstorm last summer.  As the rain pelted down from the sky, steam rose up from the pavement.  My gutters overflowed, my water runoff buckets filled within minutes with dust-stained, but very welcome water.

My raised beds looked like they had had a great big thirsty drink.

But, a little closer inspection revealed the truth.

The drenching had not even made it through the mulch to the soil. Under my layer of thickly applied mulch,  it was as dry as a bone.

Also, laying that much mulch was like sending an engraved invitation to every slater bug in my suburb to come on down.  They demolished everything that was photosynthesising.   I even contemplated a chemical solution, but since it was so toxic it couldn’t be used on edibles, I put that out of my mind very quickly.

So what to do?


My tomato patch, planted with parsley, borage and cucumbers, but very lightly mulched.  And one weed.
My tomato patch, planted with parsley, borage and cucumbers, but very lightly mulched. And one weed.

This season, I have had a very light hand with the mulch, literally only using a thin sprinkling.     I am also companion planting much more than before.  Any bare spots are filled  as quickly as I can with an assortment of calendula, cornflower, nasturtiums and  herbs, anything that will cover the ground, provide pest protection and/or help the veggies along.

Each bed now has at least 3 plant varieties to help shield and shelter.  This  approach is working an absolute treat.  I have fewer slaters (or appear to) because they really have nowhere to hide.

So now, when it rains, the soil actually manages to get wet.

My "ratbag" bed planted quite closely with a mix of lettuce, cornflowers, leeks and celery, very thinly mulched.
My “ratbag” bed planted quite closely with a mix of lettuce, cornflowers, leeks and celery, very thinly mulched.

Yes, I have more weeds to pull out, but not as many as you may think.  Plus, my weeds are all gobbled up by grateful chickens.  The soil is slowly recovering.  Incorporating more clay into my sandy soil appears to have done much more to improve the water holding quality of my sandy soil than mulching.

The only weed I could find in my experimental "ratbag" bed.
The only weed I could find in my experimental “ratbag” bed.

Since doing a bit of research, I have found a fantastic piece by a local horticulturalist John Colwill otherwise known by his alias, “Plantsman”.  Apparently, when it comes to mulch it’s the (cough) size that counts.  The best performing mulch for the veggie patch in our climate needs to to have big particles and be somewhat waterproof.  I was doing it all wrong.  The entire report on his fantastically comprehensive experiment is cleverly titled “Mulch ado about Something.”

You can find more of Plantsman’s excellent Perth-local advice at 

So now I have overcome my mulching addiction, now all I need is more rain.

Please?  Just a little more rain?

But what do you think?  To mulch or not to mulch?  What’s your experience?  Please leave me a comment below.


  1. says

    I have had very good experiences with mulch. I have a strong worn population in my patches and they thrive and feed off the old chook hay which I lay as my mulch. I always find the soil damp (I use dripper hoses in summer and periods of dry spells) So that is can permeate underneath the straw. I have found my soil has improved. But I will now keep a close eye on it to make sure that water can penetrate through!

    • says

      Ah, drippers underneath the mulch! I bet that makes all the difference! I don’t have any retic to my beds, but have been thinking of trialling a few wicking beds, which would have to be heavily mulched. My coastal, sandy soils aren’t usually frequented by worms, but I”m hoping that once the soil improves, they will come.

      Thanks Nat!

  2. says

    I don’t really mulch all that much as it seems so fiddly when I’m growing things in such small pots. I did find something that basically looks like dirt so I through that around a bit.

    • says

      I don’t miss mulches fiddly aspect at all! Especially the sugarcane mulch, one stiff breeze and it just all blew in my face rather than landing where it should have!

      Last summer’s heat dashed all my potted things, that would have happened with or without mulch. The heat and wind just zapped all the moisture out of them like it was the War of the Worlds. So now I just use pots for winter treats or things that I can move into the shadehouse.

  3. says

    Hi Melissa

    I use about 50mm thick sugar cane mulch in my vegie garden, but I remove it and throw it in the compost when I harvest the crop its protecting. You mentioned wicking beds. They are a bit of a passion with me and I have a blog with instructions on how to make them. Mine are wicking worm beds with built in worm farms, you might like to take a look. I love your blog and I will put a link to it on mine

    Kind Regards


    • says

      Hi John,

      Oh wow. I have wicking bed-envy. I love your set-up, and your explanation is so gloriously detailed! Husband is worried his next month of Sundays are spoken for, as I supervise his alteration of my raised front beds, into wicking beds :) I also love the structure around your beds, you mention you use it for insect protection, I imagine it would also be useful for my summers, to hook up shadecloth and to even offer protection from the wind. So pleased you enjoy my blog, given the high standard of your own work it is a compliment indeed. Thank you.

      Best Regards

  4. says

    Hi Melissa

    Thanks for your comment on my blog by the way, that was very nice. You’re right to think the pest exclusion system provides excellent protection against the wind and sun especially in summer.

    The “hook on”system I use for attaching the netting is particularly useful because you can change the configuration to suite the conditions. For example, I have 75% shadecloth on the south side of my main wicking bed at the moment to protect the growing area against wind and absorb a bit of solar heat. It just keeps the edge of that cold wind we get in Melbourne in winter.

    I have bird netting on the top and other sides of the bed, because the pesky blackbirds are after my worms. later when the insects appear, the vegnet will replace the bird netting, and on really hot windy days in summer (over 35deg C) I usually replace the vegnet with 75% shadecloth.

    I don’t know if you have ever googled “wicking worm beds” you will find many alternatives to my system, and some of them have your sloping problem. What they have done is to turn their beds so that they run along the contours of the slope. I have probably made an enemy for life suggesting this remedy. Tell him I would come and help out if you were not so far away.

    I hope you go ahead with the change, it really does help out with water use, fertliser use, weather potection and pest exclusion.

    Thanks again for your generous words.

    Kind Regards


    • says

      Thanks John! I will certainly check it out further. Husband might just get a pass this weekend. It has been raining all week and more this weekend, but wonderful news for our otherwise parched state!

  5. says

    So glad I found your blog, you certainly have some great information here. I have also gone back and forth with mulch. Lately I am just planting everything (lettuce, bok choy etc) very close together. this shades the ground and seems to confuse the pests, so it is a win-win situation.

    • says

      Thank you!

      Yes, I really favour that approach too. This weekend, finally have an opportunity to get out in the garden and planning to plant lots of ground covering melons…and get the soil covered before the inevitable heat arrives…

  6. Ally says

    Hi Melissa
    Just stumbled onto your blog/page. I am also from Perth and just starting out with our gardening/veggie patch. We have own our place for over 7 years and never did anything with the garden. Everything died and weeds grew a mess. Last year, I decided to grow my own food – which meant a serious tidy up of the yard.

    I have used Lupin Mulch and found that the sandy soils of Perth love it. I don’t apply it very thick – so that way the soil does get wet etc – but its on thick enough to keep the weeds down.

    Lupin has lots of good, key ingredients that helps my fruit trees and veggies grow.

    I am really enjoying it actually!

    • says

      Hi Ally, so pleased you found me!

      I must admit, I’m a recent convert of lucerne mulch too. LOVE it. I had a huge bag delivered to do my front yard, (you can see the price and details here ) and I will need to order another to do the backyard, (a great gift idea for Mother’s day kids!!) but it was excellent value. I still have slater issues, but it lets the rain through, seems to keep the soil underneath damp for ages and its like adding fertiliser AND mulch.

      Sounds like you are well on your way with your garden! The cooler weather and rain will certainly help progress 😉

      • John says

        The warmer weather and top watering Lupin mulch has resulted in large patches of mould. It spreads very quickly.

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