What is Garden Mulch, and Why Bother with it?

Now is a prime time to mulch. So I thought I’d devote this week’s blog to all the key mulching questions such as what is garden mulch?

The inspiration behind this blog is my neighbour Desi. I was chatting to her last night at a Mamma Mia fundraising evening in my village. No, I wasn’t wearing silver platform boots and a white short tunic. But yes, the evening did involve a lot of raucus singing and over-enthusiastic, some might say, dodgy dancing by yours truly!

Anyway, before I ‘met my Waterloo’ on the dancefloor, I chatted to Desi. I mentioned that I hadn’t decided on today’s blog topic. She suggested mulching. But I was sure I’d already covered it. But when I looked this morning, I realised I’ve not written about it in any depth. Yet to me, it’s one of the most important of garden activities, and one of the key gardening jobs for March!

So I’m going to remedy the situation right now by exploring what is garden mulch and which type to use and when.

What is Garden Mulch?

Simply put, mulch is a material you spread over your garden, typically on your flower beds, to protect or improve the area. Mulch can be organic, like leaves, grass clippings, woodchips, bark, manure. Or it can be inorganic i.e. made from non-living material such as black plastic sheeting, gravel and rubber.

I don’t like inorganic mulch. To explain why, we need to first think about the benefits of mulching.

Benefits of Mulching

Mulching is useful for a number of reasons. It suppresses weeds, it helps retain soil moisture and protects plants in winter and it can be used to make an area look nice. However, the big advantage of mulching is that it gives you an opportunity to add nutrients and structure to your soil.

But to get this nutritional boost you must use an organic mulch. Piling a layer of gravel or rubber onto a bed isn’t investing in your soil. It won’t help all the beneficial bacteria, worms and plants which live in your soil.

In contrast, by adding a layer of organic mulch to the top of your beds, you’re adding organic content to your soil. This not only adds a dose of goodness but the layer of mulch also helps the soil hold onto water but without it becoming water logged.

By providing a barrier, the mulch also reduces evaporation, which further helps your garden retain water. This reduces the amount of water your plants need. Given all the discussions around the importance of conserving water, mulching is an environmentally sound habit to get into.

Added to all this, mulching also can help keep down weeds! Hurrah! Saving you so much time and backbreaking effort.

And if you’re a tidy-type, (I’m not) it also makes things look a lot tidier.

What is Garden Mulch – Inorganic Mulches

If I’m to answer the question ‘what is garden mulch’, I know I must cover off inorganic mulches. However, when you consider the benefits of mulching you quickly realise that inorganic mulches just don’t stack up.

Inorganic mulches don’t break down like their organic counterparts. This may mean they don’t need to be reapplied frequently, but to me that’s where their advantages over organic mulches end.

Inorganic mulches do not add any nutrients to the soil, in fact some can prevent nutrients from reaching the soil altogether.

They often do not help much in retaining soil moisture or protecting plants through winter. And in many instances they do more harm than good!

Decorative Rocks

For instances decorative rock mulches might make things look neat and tidy but they are heavy to work with and can absorb and reflect heat from the sun. So if you’re not careful they will cause an area to become too hot and dry for many plants.

Plastic Sheeting

Sometimes you might be confronted by a large weed-prone area and feel plastic sheeting is the answer. I will concede that it’s an effective way to suppress weeds. And yes, it lasts a long time (too long dear reader). But while it stops weeds coming up it also stops water, air, or nutrients getting down to the soil. So you certainly don’t want to use it near plants, especially trees and shrubs. Even if the trees are some way away, they will have large root spreads which the sheeting will interfere with.

Plastic sheeting kills many of the beneficial insects, worms and microorganisms that live beneath our soil and keep it healthy. It prevents your soil from breathing. Indeed, to my mind, with plastic sheeting, you’re smothering your soil, not just the weeds.

So if you’ve a large weedy area to clear and prepare before planting, I’d suggest you consider sheet-mulching, using an organic mulch. I describe this later on.

Landscape Fabric

Good quality landscape fabric will smother weeds while letting in air, nutrients and moisture. But it looks awful. You can cover it with organic mulch to make it look more appealing. But if you’re going to do that, you may as well skip the fabric phase all together in my book! So long as you weed pretty well to start with, an organic mulch on its own, will keep weeds at bay brilliantly.

Rubber

You may put rubber down around a children’s play area to make the landing a bit softer when they fall. But I see no gardening merit in otherwise using rubber. Yes, it will help with weeds and water retention, and you can get it in jazzy colours. But I think coloured rubber looks unnatural and organic mulches do the job just as well. And do you really want a load of man-made rubber in your soil?

What is Garden Mulch – The Organic Options

For me organic mulches win hands down every time. Not only do they deliver the benefits of mulching, but while they’re breaking down, they attract beetles, worms etc which provides food for birds.

Here area some organic mulches that I favour.

Ornamental Bark

For mulching my flowerbeds I often use ornamental bark. It’s often finer than the bark in this picture. I think it looks attractive and unlike woodchips it doesn’t cause nitrogen loss in the soil. Indeed ornamental bark actually conditions your soil.

Strulch

Strulch is brilliant stuff. It’s made from straw and smells sort of marmitey. Which given I’m a bit of a marmite addict is another plus! It costs more than other bought in products but one mulch with it will last for two years. Also, it seems to deter slugs and snails. I’m not sure whether it’s the scratchy surface or the smell which puts them off but it does seem to work. So I use this on my bed which has lots of hostas!

Leaf Mould

I’m a huge fan of leaf mould as a mulch. If you have trees, you can make leaf mould yourself for free. It feels so natural to make use of the leaf litter from your own garden.

It only takes about a year for a bag of leaves to become lovely leaf mould!

As they die, trees reabsorb most of the nutrients contained in their leaves. As a result, leaf mould doesn’t contain any nutritional value. But it still offers the other benefits of mulch – improving soil’s structure, inhibiting weeds and helping with water retention.

Garden Compost

Like leaf mould, garden compost is brilliant because you can make it yourself. But unlike leaf mould garden compost as a mulch offers nutritional value too!

Well Rotted Manure

Horse manure is packed with nuturients and therefore a great mulch around hungry plants such as roses or on veg patches. But do make sure it’s well rotted. That means it has rotted for at least two years. If it isn’t it may ‘scorch’ your plant leaves and even remove nutrients from the soil as it breaks down. Disaster!

Mushroom Compost

I’ve not tried mushroom compost but have heard good things about it. People say it’s lovely and light to use. I’d just give one word of warning. It has a high pH. With my D in chemistry O’level, (oh that ages me) I’m clearly no scientist. But I do know that a high pH means it’s limey. That means that while it’s ideal for lime-loving vegetables such as cabbages and broccoli, be careful not to use mushroom compost around lime-hating, ericaceous plants – your heathers and camellias.

Newspaper/Card – for Sheet Mulching

Mulching is brilliant for supressing weeds. However, if you’ve a really large, weedy area which you want to completely clear and prepare for planting, and you want to smother what’s growing there to kill it off, that will involve a lot of organic mulch!

Using only mulch to prepare the ground will require you to add 8-12 inches of mulch over the top of the existing vegetation.

However, that doesn’t mean you need to reach for sheets of black plastic!

Try sheet mulching instead. This is where you use newspapers/carboard (which break down) combined with organic mulch. With sheet mulching you’ll only need 3-6 inches of organic mulch on top of the paper/card.

The sheet mulching layers will take at least a season to break down. But if you do it in Autumn, you will be good to go in the Spring with your planting.

OK- We’ve Covered What Is Garden Mulch – But What Else?

Some people swear by straw as a mulch and it does rot down slowly, so lasts well. But I think straw looks too messy (and I’m quite a messy gardener).

When and How to Mulch

Having hopefully covered off what is garden mulch, the when and how to mulch is thankfully much more straightforward.

The best times of year to mulch are spring and autumn. Mulch in spring to give everything a boost ahead of the growing season. Around spring bulbs it will feed the bulbs at the crucial time as the leaves are dying back.

If you’ve roses which suffer from black spot (all of mine do), I’ve read that a spring mulch also prevents rain splashing the black spot spores in the soil on to the new rose growth.

The autumn mulch is to provide all the benefits of mulching plus a protective layer for plants and their roots as winter approaches.

How

If you are mulching in spring, wait until the soil has warmed a little and is moist. That’s because, if the ground is frozen hard, your layer of mulch may actually inhibit the warming up of the ground!

Applying mulch is very easy. Simply put down an even 2 inch (5cm) layer of your chosen mulch. It’s better to put a 2 inch layer on half your bed than to put a 1 inch layer on the whole thing. Use your hands to put it around your plants. Don’t rest the mulch against the base of woody stems such as shrubs, as it may rot them and damage them.

I wouldn’t go deeper than 2 inches as you don’t want to make it too difficult for bulbs and plants to break through.

It’s best to weed the area first. Also make sure the soil is moist. If it isn’t, give the area a water before mulching; you want the mulch locking in water, not keeping water out!

What is garden mulch? It’s Therapy!

Well, I hope I’ve answered what is garden mulch, when to use it and why. As you can see, it’s a wonderful aid to any garden, and something I do without fail every year.

But if I’m really honest, I think mulching does me as much good as the garden. It feels like such a positive thing to do for your garden. It’s an opportunity to get your hands in the soil – to feed, nurture and tidy in one fell swoop.

What could be lovelier than a day spent doing that. Happy gardening….x