Garden Mulch Facts and Fantasies

You want to know about garden mulch but the first thing you have to know is summer is here and the living is easy in my garden

As municipalities across the country impose water restrictions, a mulch becomes a gardener’s best friend. In my own gardens, I’ve use leaves from last year as a mulch over the entire garden and they’re doing their thing quite nicely now.

I was at a garden this past weekend that used mushroom compost as a mulch. The gardener bought it by the truckload and spread it approximately a half inch thick over the vegetable garden. She said the worms got most it by the end of August but by then it had done its duty of smothering out weeds in the vegetable patch and keeping her ground a little cooler.

Salt didn’t seem to be a problem in these small quantities (thicker applications would have been a problem) and given that the worms are eating it that quickly, it is turning into high quality fertilizer very fast.

I’m still not a fan of using mushroom compost in large quantities as mulch nor does the analysis of it suggest it is good fertilizer. Rather it is excellent marketing on the part of the mushroom factories to get rid of their waste material. But a little bit seems to work for this gardener and as the price is right for her (her husband is a trucker) this would work.

Wood Chips

Wood chips are another common mulch and these work quite nicely in gardens.
I saw several large beds with the coloured mulch and I have to say that I think this product is quite hideous-looking (but what do you really think Doug?).

If you can see the mulch in my gardens, it means I’ve failed as a gardener. I try to put my plants so when they mature, they shade out the ground under them and restrict weeds too.

I like a mulch that disappears into the background, one that serves a function in the garden without being obvious about its existence.

For me, the stars of the garden are the flowers and leaves rather than the ground and anything that competes with the flowers for colour is taking away from the visual impact of the plants.

Coloured mulches scream across the garden and take away from the visual effect of the plants they are supposed to be helping. I know there’s a lot of this stuff sold right now but I’d rather get my colour from the shrubs and flowers and not the mulch. I can’t even begin to tell you how bright one garden area was with literally tons of the stuff spread around the garden.

Stone as Mulch

I was also asked about using stone on gardens this past week and my take on that is that it is fine if the garden is an alpine garden and meant to be rocky.
It is also fine if you’re not planning on every digging in the garden again and like the look of stone.

But, if you ever plan on planting something in there and digging around in it, stone makes a terrible mulch. You’ll wind up burying some of it as you dig and you’re not going to be happy.

And to make things even more interesting, I think weeds like to germinate faster in stone mulches than in bare soil or bark type mulches.

Unless you have a real reason to use stone, I’d stay away from it.

We bought a house once with a stone mulch in the garden, and it was the worst thing I have ever gardened in. I would never buy another house with this material in the garden unless my better half insisted on it.

Little Known and Discussed

One of the things I’ve had trouble with this season under my mulch is slugs and snails. The dampness has made them quite happy and they’ve been eating some of the emerging perennial shoots before they can reach through the mulch. I discovered this by accident this past week when I was about to replace a plant I thought had died over the winter.

Instead of dying, it was trying to throw shoots but they were being eaten as fast as it could grow new ones.

I pulled the garden mulch away from the plant and let the immediate area around it (12 inch circle) dry out so the slugs won’t venture there. I have high hopes for new shoots and leaves by the end of the week.

I’ve lost perennials in the past and now I’m starting to wonder how many I’ve lost to aggressive slugs under the mulch.

So from now on, I’m going to leave a small circle of unmulched ground around each perennial when planting and growing. It never ceases to amazes me what I’ll learn the hard way when it comes to gardening.

Digging in Wood Chips

I know that some folks ask about what happens when you accidentally dig some garden mulch into the soil. This happens, particularly in flower beds, when you are digging and planting in close quarters.

This material is mostly composed of cellulose so fungi are going to attack it. This is fine and will not be a problem to the normal soil biology other than you’ll be giving a source of food to fungi.

They’ll break it down and make it available to other soil microorganisms.
If there’s nitrogen in the mulch, then good bacteria will attack it and make that nitrogen available to the plants. The problem comes in when the bacteria demand nitrogen to live themselves while they’re working and this demand can strip down the amounts of available nitrogen in your garden.

If you’re only accidentally burying a little here and there, you won’t see a problem in your garden.

I know that some folks tell you that using garden mulch will rob the garden of nitrogen and this is true if you’re burying cellulose products in large numbers but the odd chunk or three of mulch isn’t going to hurt anything.

And wood chip garden mulch that is simply on top of the soil isn’t going to hurt a thing. The microorganisms in the soil will only work on the top surface well above plant roots.

What about sawdust in the garden? See above. As long as you’re not digging it into the soil, it will be fine on the surface. Spread it thinly though so it doesn’t act as a water barrier.

But mulch on the garden is a good thing for our plants and as long as you stay away from that coloured stuff, you won’t go wrong.


2 thoughts on “Garden Mulch Facts and Fantasies”

  1. I started using wood chips this past year for the first time because we purchased a large wood chipper (will take up to a 6″ log). I am completely satisfied with using wood chips for mulch in the garden and flower beds. One thing I did learn, in my area here in central Missouri, we usually have a lot of rain in April, May and early June. Some of the plants were showing signs of too much moisture and I had to pull the mulch back until July when the heat and less rain season started. Then I put the mulch back around the plants, corn, Stevia, peppers and cucumbers. For the rest of summer, I had to water much less than the rows mulched with old hay.
    Overall, I think the wood chips will be my go to, just have to pay attention to the time of year. Will be incorporating wood chips into the entire garden as my pile gets larger!

  2. The only thing to pay attention to is whether you are going to be digging in the garden. If you dig your vegetable garden, you really want to avoid incorporating that mulch into the soil. If you are using a no – dig system, then woodchips are fine. So use them on the surface, but not mixed into the soil as they will suck the nitrogen from the soil if incorporated. On the surface, they do not do this.

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