Mulch Isn’t Just About Good Looks
There’s more to mulch than just making things look neat and tidy. It also serves several purposes, including water retention, weed suppression, temperature control, and restoring some nutrients to the soil as it breaks down.
Pro Tip: Jenn Nawada, This Old House landscape contractor, breaks down the key functional benefits: “To keep in soil moisture, it really helps keep the moisture in the soil once the water penetrates through. That’s number one. Number two, soil temperature. It helps regulate the temperature—in the summer it keeps the roots cooler; in the winter, it keeps them more insulated.”
How To Estimate How Much Mulch You Need
Mulch is quantified in volume, so it’s important to understand the equations. First, for new beds, aim to add about 3 inches of mulch. For existing beds, aim to add 1 inch.
- If the area is 10’x10’, and you’re adding 3 inches of mulch, the equation looks like this:
- Length x Width x Depth = Cubic Feet
- (To get 3 inches in feet= 3”/12”= 0.25’ )
- 10’ x 10’ x 0.25’ = 25 cubic feet
But, nurseries don’t sell mulch in cubic feet, they sell it in cubic yards. So, to find how many cubic yards you need, take your cubic feet and divide it by 27:
- Cubic Feet / 27 = Cubic Yards
- 25 / 27 = 0.926 cu. yd.
Pro Tip: Jenn, This Old House landscape contractor, offers a handy shortcut: “A yard of mulch covers 100 square feet three inches deep.” If you’re buying bagged mulch instead of bulk, she notes that bags typically come in two-cubic-foot sizes: “If I know I have 25 cubic feet, take a ten-by-ten foot area, three inches deep. That’s 25 cubic feet… You get 12.5 bags or 13.”
Types of Mulch Options
There are several types of mulch available:
- Gravel is great for high-traffic areas or areas where erosion can be an issue. The stones will absorb heat so it’s important to use them around drought-tolerant plants.
- Rubber mulch is nice for playgrounds and playsets, but it doesn’t restore nutrients to the soil.
- Dyed mulches come in a wide variety of colors and they’re great for dressing up garden beds and walkways. They’re not the most organic option, however, due to the dye.
- Organic mulches like hemlock, leaf litter, pine bark, and buckwheat hulls are excellent options because they have distinct colors without the dyes and break down over time to restore nutrients to the soil.
Pro Tip: Jenn Nawada, This Old House landscape contractor, cautions against dyed mulches: “This is what I have a problem with—is that they use dyes in it. And so dyes have chemicals in it, but they do it to have the color last, which I like to stay away from.” She notes that the dye “is a color preservative and so it locks in the color and the color lasts longer. But then that’s also going to leach into your soil.”
Resources
- Organic: Most organic mulch options can be sourced at a local nursery
- Leaf mulch: Ground organic leaves. High in nutrition.
- Hemlock mulch
- Pine bark
- Buckwheat hulls: More formal gardens or decorative applications
- Gravel: Commercial or industrial
- Inorganic: Color preference, water retention, and weed suppression
- Brown mulch
- Black mulch
- Red mulch
- Rubber mulch: Playground application or high traffic area
