Mulches: pros and cons Part I - organic mulches

 Recently I wrote about the basics of mulching and that -  of course! - let to a follow-up question: what are the pros and cons of the various types of mulch materials?

In that article, I said:

"Typical organic mulches include home-made garden compost, leaf mold, bark chippings, micro bark, farmyard manure, "strulch": inorganic mulches include shingle, gravel, rounded pebbles, slate, rounded glass. Even old carpet, newspaper, brown paper, cardboard boxes - it depends on the "why". "

And now we have time to run through each of those, in turn.

Let's start with the organic mulches, then come back to the inorganic ones.

1)  Home-made garden compost

This is what you make yourself: it's the perfect way to recycle your own garden waste into something useful and wonderful. The nutritional content will be pretty variable, but does that matter? No, it doesn't, you are taking the plants full circle, using the dead parts to feed the living parts. This is what would happen in nature - without us, faffing around in the beds and borders, the previous year's plant material would just fall to the ground and eventually rot, returning the "goodness" to the soil. 

But in real life, no-one wants a border filled with mushy dead brown stuff, encouraging slugs and rot: we want to be able to see our plants, we want them healthy and floriferous, so we take away the dead material (and the weeds!) turn them into compost in our compost pens, then return the material once it has been processed.

Good points:  it's free! And you are fulfilling a "cycle" by keeping your garden's nutrients within your garden, rather than throwing them away.

Bad points: will probably be full of weed seeds! Home made compost just doesn't get hot enough to kill off the seeds and sterilise the soil, as bought-in compost does. However, what's a few weeds? Catch them while they are small, and pop them back on the compost heap to go round again!

2) Leaf mold

Wonderful stuff, I am a huge fan of leaf mold: and why not, it means taking a waste product  - dead leaves in autumn - raking them up (which we do, anyway), popping them into some chicken-wire pens in a far corner of the garden and leaving them for two years. No stirring, no feeding, no chemicals, just leave them to rot down naturally.

The resultant product does not contain much in the way of nutrients, but it does contain minerals, and it's a fantastic soil conditioner! If your soil is claggy clay, it helps to break it  up and make it more friable. If it's loose, sandy soil, it bulks it up, making it better able to support plants physically, and much better at retaining moisture and nutrients. If your soil is dusty and tired, then it adds bulk, again, improving moisture retention, and encouraging a proper ecosystem of worms and bugs. Wonderful stuff!  And it's free!

Good points:  it's free!

Bad points:  "does not contain much in the way of nutrients"!

3) Bark chippings

These are usually bought-in, in bags: they need to be loosened before spreading, as the packs are usually very compacted, in order to give you good value for money. So cut open the bag (properly!) and tip the contents into a wheelbarrow, then fluff it up with your gloved hands, and/or a hand fork or trowel. 

Once it's loose, you will observe that there seems to be twice as much of it, which means it will go further. 

If the soil is dry, be sure to water it before spreading bark, which will otherwise act like a thatched roof and will keep the soil dry! This is not good for the plants... so, ensure the soil is wet by applying bark just after it's rained: or spray it with the hose before spreading. Use a "bowling" action to spread it loosely across the soil: don't just dump it down in great lumps.

Good points: Quick, clean to spread, makes the beds instantly look fantastic!

Bad points:  birds will flick it about all over the place, because it is a lush environment for bugs, beetles, worms etc. So be prepared to rake it all back on the beds, from time to time. Small point of interest: my first EVER gardening job, 20 years ago, was mostly flicking back bark from the lawn. True story! I turned up, all nervous, and the owner ("Hi, Bobbie!") asked me to go round all the borders, flicking the bark back onto the beds. Every week for a couple of years, that was my first job of the morning: half an hour to flick up the bark, before getting on with proper gardening.  But of course, if  you like the birds, then it's wonderful, because they have a lovely time rootling around in it!

You will also need to top it up every couple of years, because it does eventually rot down and disappear.

4) Micro bark

Exactly as above! It's just bark that has been through a finer grade of chipper. Or, more likely, it's actually the by-product from bark manufacture, and comprises all the little bits which fell through the screen while the bark was being packed... or is that me, being cynical? Who knows...anyway, it's just as good as proper sized bark, it looks lovely, really freshens up the bed or border, and the birds love it.

Good points:  as above: instant freshen-up for the beds

Bad points: as above, birds love it. Plus, being smaller pieces, it rots down to nothing quite quickly, often within a year.

5) Farmyard manure

Also known, rather coyly, as "organic matter" for the benefit of people who don't like the idea of spreading poo on their gardens. Cissies! It's only processed grass, or hay (which is dried grass), that's all! It is mostly from cows, sometimes it's from horses: sometimes it doesn't even tell you, on the bag, what animal produced it... but be assured, it's always from grass-fed animals.  This is important because if you were using anything originating from meat-eaters, you would have a garden full of rats.

The contents can be quite variable with regard to the amount of nutrients it contains, but hey, it's semi-digested grass, and grass is full of nitrogen, so it's got to be good for the plants! The texture is also quite variable: some bags are full of lovely crumbly stuff, some are lumpy and cloddy, which is not what you want.

Good points:  easy to buy in nice neat plastic bags. Does not smell.

Bad points: there is no legislation forcing the producers to do any checks at all as to what drugs have been given to the animals. The "organic matter" could contain any number of chemicals, from worming preparations, right through antibiotics and into regular vaccinations,  growth hormones, etc. We just don't know.  It's nice to think that all such drugs would be broken down by organisms, before it reached our gardens, but we honestly don't know. 

5a) Horse poo collected locally

A sub-set of "organic matter" is manure you've collected yourself from a local horse yard: most of them have to pay to have the muck-heap taken away, so most equestrian yards, and especially private owners with just a couple of horses, are more than delighted for you to take it away, for free. The "catch" is that you have to fill your own bags, but the good thing is that if you are filling your own bags, you can pick the good stuff. 

"Good stuff" is defined as material which does not smell the tiniest bit stinky, and in which you can't see any individual clods. As with home-made garden compost, the golden rule is "if you can see what it used to be, then it's not ready".  If you can see leaves, or sticks, or stalks - or, with horse manure, if you can see defined clods - then it's not ready. The phrase "well rotted" means exactly that: you can no longer identify any components, it's just one homogenous mass. This means finding the oldest part of the muck-heap - if in doubt, ask the owner.

Good points:  If it's local horse manure, it's free!

Bad points: you have to collect it yourself... and although the material you are taking is not smelly, you often have to wade through a lot of stinky stuff in order to get to it, because - by definition - it's at the back!

6) "Strulch"

This is a commercial product, it's "Mineralised Wheat Straw" / It's actually a by-product from flour production: the heads containing the grains are harvested to make flour, and the stalks are otherwise wasted - that's what used to be burned in the fields every year. Strulch is a patented process, so we can't find out exactly what they do to it: the official website bangs on about adding minerals, and how the process "stabilised and colours" the straw. "Colours" it? To make it brown, so it looks nice?

It's heavily plugged as being an alternative to peat, suitable for vegans, and for being organic, and so on and so on and so on. Frankly, I'm biased against it right from the word go, by this evangelical, holier-than-thou attitude, but there you go, that's just me! I met one lady who swears by the stuff. 

It's comparable in price to farmyard manure, and the producers stress how "light" it is, which makes it easy to apply.

Good points:  Light, easy to apply.

Bad points: I have never used it, so I can't add any bad points!

So there  you go, that's a bit of insight into the various organic mulches: stay tuned for the next exciting instalment: Inorganic mulches!

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