The Dirt On Mulch: How To, When To, What To Use Where

My front yard, now that the sweet potatoes are gone ...

My front yard, now that the sweet potatoes are gone ...

November 4, 2014

I think everyone should mulch, no matter what sort of climate, soil, or location you have.

Now, why do I think this? Why should YOU mulch? How can mulching actually HELP with the problems you're facing in your yard?

First, why do I think everyone should mulch?

Mulching helps your yard in many ways: suppressing weeds and moderating soil temperature are the two biggest ones.

But when you choose the right mulch, you can do things like improve your soil's moisture and drainage, and of course mulch can make your garden plot look nicer, if you like a more minimalist garden.

My garden looks pretty bare and "mulchy" right now because I've dug up my sweet potatoes and my fall greens haven't come in yet.

How do you use mulch?

Using a thin layer of mulch on top of the soil when you sow seed allows the seed to germinate and grow without having to push through a layer of soil. Also, mulch keeps in moisture on the ground surface so you don't have to worry about your seed drying out.

A thick layer of mulch (3-4 inches/8-10 cm) will suppress weeds already there -- much easier than digging out every little weed, especially when you're facing something like Bermuda grass (Cynodon dactylon)!

Light colored mulch can help cool the soil in very hot climates, whereas dark mulch can heat up the soil in very cold climates.

The use of colored mulch in this way can help you grow plants which are just outside what you "should" be able to grow for your plant hardiness zone.

Let's look at the kinds of mulch there are, and when you should use them.

Organic mulch

Organic mulch is what most people think of when they think of mulch.

Some examples are wood chips, leaves, grass clippings, peat, straw, compost, and so on.

Cardboard and newspaper are also considered organic mulch, but these are only used in very specific circumstances, such as if you want to smother all plants already growing in the area.

Organic mulch is great for adding organic material to your yard, evening out the texture of your yard, and keeping the ground moist.

Keeping in moisture, however, is probably not a great thing if you live somewhere which is very wet, rains a lot, or is on the cool side, because you can get a lot of problems with pests such as snails, slugs, and mold when using organic mulch in these conditions.

So I recommend that if you live somewhere cool and wet (US Pacific Northwest and the UK, I'm looking at you) that you DO NOT use organic mulch.

So what do you use then?

Inorganic mulch

There is a wide variety of inorganic mulch available for those areas where organic mulch is not a good idea.

These include things like rubber mulch, sheet plastic, landscape cloth, rock and gravel mulch, and glass mulch.

Each of these can be useful in specific circumstances:

  • Drainage

    In areas where you need extra drainage, rock and gravel mulch can be very helpful.

    Not only can gravel mulch help you to grow dryland plants in areas where they normally might not do well, they can help those of you with very wet conditions suppress weeds while improving your soil's drainage.

    Another advantage of chipped gravel and other sharp rock mulch such as lava rock is that slugs and snails dislike sharp items and will avoid any areas you use this sort of mulch on.

    If you like, you can use regular gravel as a first layer for drainage then a more decorative and/or sharp rock or gravel for your top layer. This can save money when dealing with more expensive decorative mulch.

  • Heavy duty weed suppression

    Plastic mulch and landscape cloth are both wonderful for suppressing weed growth in areas such as under cacti and other thorny plants (which you do NOT want to have to weed around!), under paths, on steep slopes, and so on. I find that landscape cloth is a bit more durable in areas which will be walked on.

    Plastic sheet mulch can also be useful in the short term to solarize the soil and kill existing plants in preparation for planting. Just realize that you'll also kill quite a few beneficial organisms in the soil along with them.

  • Decoration

    Glass mulch comes in many colors and is gorgeous as a decorative mulch, in rock gardens, etc. It's best to use it in areas which will not be walked on.

  • Play areas

    If you need weed suppression in a children's play area, landscape cloth covered with a thick layer of recycled rubber mulch is as close to an ideal situation as you can get.

    No need to worry about splinters from wood chips or injury from falling on sand or rock, recycled rubber is non-toxic, and if you have a tall and wide enough edging you'll get very little spill-over (plus you can make the kids put back anything that does get out before they come in!).

  • Improving plant growth

    Red plastic sheet mulch seems to stimulate the growth of tomatoes (Solanum lycopersicum) while suppressing weeds, so it's a popular choice for those who love growing them.

What do you think? Has this given you any ideas about using mulch in your garden?

Return to the Members' Area main page

Comment policy: please use your real name. "Anonymous" comments will be deleted.

Click here to post comments

Return to Beginners

If this site has helped you and you wish to help with costs, click here.