Mulch: An Overview of Advantages and Disadvantages in Landscape Design

Mulch isn’t just pretty! You may look at a freshly mulched landscape bed and see how fresh and nice it looks. The benefits are far more than just for looks. Sure, mulch looks fantastic! It’s just like the icing on the cake! It gives a smooth textured and colored appearance, just like frosting.

Ok, how to write about mulch! Let’s start with the looks of it. There are colors and choices for mulch. There’s the brown type, dark brown, cedar, black, wood chips, and even rubber. In your landscaping, I don’t usually recommend wood chips. They will tend to have branches mixed in and they don’t look so great. They’re lightweight and may float away with water and rain. The wood chips are made from the pulp of the wood and therefore will attract more insects than the shredded bark mulch. The colored mulches do have a dye in them, and they will retain color much better than the natural undyed brown bark mulch which tends to gray as it ages. The rubber mulch and some other specialty mulches are great for playground uses.

You can use weed fabric under mulch, but I don’t usually recommend it. Here’s my reasoning. The weed fabric is great at keeping weeds at bay for the first couple of years. Then, you’ll notice that the mulch starts to decompose. That creates a soil on top of the fabric. Then, weeds germinate in that soil on top of the fabric. When you go to pull the weeds, the fabric pulls up with them and you end up with a mess. The best way, in my opinion, to keep weeds down in a mulched area is by keeping the depth of the mulch at about 2”-3”. You will want to refresh or top off the mulch every other year or so. Even though this is an expense, it’s worth it. It’s not a bad idea to use a product similar to ‘Preen’. If you can, use the Preen under the mulch (before you add new mulch). This product helps to prevent weed seeds from germinating. The best trick to keeping up with weeds is simply to “keep up with them”! Regular weeding helps to prevent their spread. Also, keeping up with the depth of the mulch helps to prevent weeds. I wish I could just tell weeds that they’re not welcome in the landscape design, but alas… weeds are weeds.

Always keep a nice clean edge to the mulch beds. This can be done with an edging spade or a nice small flat type shovel. Do not pile mulch up onto the trunk of a tree. Doing that may cause fungal problems, so be sure to pull the mulch away from the base of all plants.

Advantages of Mulch

Mulch helps to reduce watering. It will keep the soil shaded and act like a sponge and help keep the soil more moist than it would be if it were bare. The wind also can’t get to the surface of the soil if it’s covered with mulch. If your irrigation comes off city water, you’ll appreciate that. Plants appreciate it too! Mulch will help protect the plant's roots. Some plants really like their roots to be cooler, so mulch does that too.

Not only all of that, but mulch will enhance the nutrients in the soil too! Mulch will be sold either by the bag or in bulk. Many do-it-yourself landscapers choose bagged mulch for the convenience of it. It’s easy to take home in your vehicle and stockpile at home in a convenient place. It is more expensive than bulk mulch though. If you order bulk mulch, it’ll be cheaper, but don’t forget that there’s a delivery cost. Then, they’ll need a designated place to dump it. When you’re done moving that mulch to your gardens, there will also be the cleanup of the area where the mulch was. It might even need to be reseeded if it killed a lawn area by being there too long.

Aggregate

Aggregate, i.e. small rock, is also a kind of mulch. When using aggregate, I do suggest that you always use a weed fabric under that. There are different sizes and colors of aggregates. For example, there is 1 ½” aggregate which is generally a mixed gray color with angular edges. There is ¾” aggregate which is the same color but smaller and is often used in the “drip edge” areas around the foundation of the house. Rounded aggregates can come in a tan or other color and look great! Aggregates do not need to be replenished like mulch does. It is possible to get a soil to develop on top of the fabric which is underneath the aggregate. This happens mostly from fallen leaves decaying on the rock, so be sure to use a blower and keep your rock areas clean so that you are less likely to have weed problems in your aggregate areas. The lower maintenance and not having to refresh aggregate like you do mulch is a benefit. Aggregate can be handy on a sloped area and can look amazing in rock gardens. Aggregates are terrific for creating “Dry River Beds” too. Aggregates play many roles.

Disadvantages of using aggregates in the planting bed areas

Aggregate looks ‘heavier’ and more commercial. If you’re going for more natural beauty, be careful how you plan the aggregate areas. They can look amazing, but just be careful. Aggregate is more difficult to install than mulch. Aggregate isn’t as ‘friendly’ to the plants. Mulch is more beneficial to the plants by cooling the area, keeping in moisture, adding nutrients, etc. So, weigh the positives and negatives on both aggregates and mulch. Your Landscape Designer can help you decide what products you want to use in certain areas. We can look at different mulch colors and placements. We can look at different aggregate choices and how we would use them.

Plan, Plan, Plan, and Install, and ENJOY!!!