A beginner’s guide to mulch. What is it and why would I do it? Let’s look at both organic and inorganic mulches and talk about why you should and, how to mulch in both the vegetable garden and in the flower beds. Straw, gravel (grit), bark or weed proof membrane. The seasons are changing for me now and going from autumn to winter means mulch is important in my beds to protect the plants and soil. But it’s not just a winter thing, Mulch is important in spring and summer too.

Do you ever hear gardening terms or things you are “meant to do” but think “I have no idea what they are talking about?” Well, you are not alone, so let’s talk about mulch, in proper simple terms. Let’s lose the jargon and let’s talk about what is mulch.

What is mulch

Well basically, mulch is a covering that you put on top of your soil. OK, that’s the key, on top of the soil. And this bit can sometimes cause a wee bit of confusion because sometimes people will talk about compost. Now the thing is compost can be a mulch and we’ll cover that in a bit.

So I had a wee look around my garden at examples of mulch and I found four I can talk about with you. Two are in-organic and two are organic. Just a wee note though, when I say organic here, I simply mean that it was once a living thing, its not organic in the sense of chemical-free. The two organic ones I have are probably the most commonly used in gardening, to be honest, the first is shredded bark.

Now you guys have seen me use something similar before and that’s woodchips or shredded wood. This looks pretty similar but just be careful because woodchips or shredded wood are not prepared for use as a mulch, meaning they haven’t been partially composted and heat-treated (by hot composting). The reason you want this is that fungus and disease that was present in the wood can stay and you don’t want to be adding that to your garden if you can help it. So to be safe, always check to make sure the bark mulch you use is meant to be used as a mulch. It will be labelled to say so.

The other organic mulch I have in the garden is straw. You’ll see me using this in the strawberry bed quite often as well as in the veg beds. I tend to use this in the veg beds (rather than bark) because it’s really easy to move around and plant through, and given I can often be sowing seeds at different times in the veg beds, I need to be able to access the soil all year round. Straw makes this easier than bark.

Now I should point out here that straw and hay are different. Straw is ok for mulching, hay is not. Hay can still have seeds etc in it so avoid it 🙂

OK next it’s in-organic mulches and the first of these which we use is good old grit. You’ll probably see it labelled as horticultural grit and in Scotland, we call that chuckies. Basically small stones. Now you guys have seen that we have red chuckies around the beds and other areas of the garden and that’s the ones that we walk on. Those are larger, so good for that, but for mulch we use something much finer and it’s purely for aesthetics it goes on as a mulch on the beds that are quite visible because, you know, we want it to look nice.

It works brilliantly as a surface for the bed, looks great, helps with weeds.

Talking of weeds, the other one I’ve got is good old weed proof membrane. I have heaps of this stuff in the shed because it is awesome for things like strawberry beds but every year I forget about it and I plant the bed up (I did it again last week) then remember the mulch. The problem is that with this stuff, you need to put it in place BEFORE you plant up your bed and then you cut holes through it and put the plant through those holes into the soil. That’s just a tad difficult if you’ve already planted up – hence why I have heaps of this stuff sitting unused. NEXT YEAR, I’LL REMEMBER NEXT YEAR!

So there are the four mulches we have, bark, straw, grit and weed proof membrane. Now compost is one that causes confusion. If, like me, you dig compost into all of your beds because that organic matter helps to really enrich the soil and improve it – that is a soil improver. However, if you put it on the top – spread it across the whole bed on top of the soil and don’t dig it in, then that’s when it’s a mulch. So compost can be a mulch and… that’s obviously an organic mulch 🙂

How to mulch

Just to warn you, it’s incredibly complicated, you might not fully understand this…

What we do is we put about a two to three-inch layer, no more than that, and we spread that on top of our beds around all the plants and things but being careful especially with the organic stuff, you don’t want to pack it up against the stems because that can just encourage things to rot. Instead, you want to spread it as a around your plants giving the stems a wee bit of space. That’s it, just spread a layer over the top of your beds, pots, containers etc. I told you it was really complicated.

Why do we mulch?

Well quite simply, in summer it helps to keep moisture in your soil. If it’s really sunny and hot (never is here in Scotland but hey) if you mulch your soil, it helps protect it from the sun’s heat, keeping moisture in. In winter (which is why I’m about to do it) it’s like a wee blanket that keeps your soil and your plants all protected a wee bit from the cold and the frost

And remember we said weed proof membrane? Well, mulch also helps to reduce the number of weeds that come through because it blocks the light. Different mulches will stop weeds to different degrees. Like the straw in my strawberry bed. It doesn’t completely stop them but it really does make a difference. You’ve seen me pulling weeds out the strawberry bed when I’ve got straw mulch in there. But trust me, it’s much less than there would be.

We’ve got the grit in the rockery and the shrubbery out front and it makes a massive difference and the bark mulch in the flower beds in the back garden is fantastic for this. Weed proof membrane obviously will completely eliminate them which is why it’s called weed proof but I keep forgetting to use it. SO I can’t comment 🙂

OK now the reason I use different things in different areas as I’ve mentioned, one is purely aesthetic, the grit for instance. It’s very visible and in areas where it looks nice to have that nice bright grit. The vegetable beds I use straw because this can actually be kind of incorporated into the soil over time without it being a big drama, and it’s easy to plant and replant through it. If I want, I can also add it to the compost bin at the end of a season if I am replacing it and it counts as a brown in the compost.

Bark is a bit of both, we use it mainly in the big flower beds number one, it’s aesthetic because the bark is dark and looks nice, it’s not as easy to plant and replant through but I don’t need that so much in the flower beds so that’s fine. Here’s a thing though, you can get coloured bark to use as a mulch, if maybe you have a colour theme for your garden. I’ve seen bark died red and other colours. To be honest, I wouldn’t go near that stuff, I wouldn’t want to put died wood into my garden, but each to their own.

Common worries

With bark, it’s maybe a good thing to point out, that some people worry about putting it on their beds because this hasn’t finished breaking down yet and as it’s breaking down it can leech some of the nitrogen from the soil. So some people worry about using it. I don’t because I do put so much organic matter and feed my soil as much as I can so I’m not really worried about this too much because I know how good quality my soil is but I thought I’d mention it as some poeple do worry.

OK in a nutshell that’s what mulch is and like I say we’re just going to put a couple of inches, maybe up to three inches on top of the beds, no more than that. Something else I’ll point out is that organic mulches like bark will break down over time. So you might want to replace it every couple of seasons or so. Again, I just shovel it all up and it goes into my compost. So no waste and bonus browns 🙂

So there you go, a whistle stop tour of mulch… these fancy gardening terms are actually quite simple when you get stuck in 🙂