Prepare summer soils with a mulch blanket

Blog Post
With summer just around the corner, it’s time to start getting your garden ready to survive (and thrive!) through hot temperatures. We’re here to help Portlanders reduce outdoor water use while growing the garden of their dreams. Mulch is an important step to making your yard more water efficient.

Mulch giveaway!

Our friends at the Portland Bureau of Transportation (PBOT) are giving away FREE composted mulch through May 1, 7 a.m.–5 p.m., at their Sunderland Maintenance Yard (9325 NE Sunderland Ave, Portland, OR 97211-1712).

For more details, see PBOT’s Facebook event.

Free Compost Days from April 22 – May 1. Logo of US Composting Council and Portland Bureau of Transportation (PBOT). Hands holding rich dark soil compost.

What is mulch?

Mulch is any material that’s spread over the soil’s surface. It can be organic, made from bark, wood chips, compost, and even aged manure. It can also be inorganic gravel or river rock. No matter what it’s made of, mulch acts as a protective layer for the soil beneath it.

Benefits of mulch


Mulch significantly reduces the amount of evaporation that happens at the soil’s surface. With less evaporation, the soil can retain moisture longer. This means that plants will stay hydrated, and you won’t have to water them as often. Mulch also prevents the surface of the soil from becoming compacted from water impact. Preventing soil compaction keeps your soil fluffy and able to absorb water to greater depths.

Weed control

But the benefits don’t stop there—mulch also prevents the growth of weeds. By blocking sunlight from reaching the soil, young weeds cannot receive enough light to produce the sugars they need to grow. So before using a chemical weed killer, try mulch.

And more!

Mulch does all of this while also encouraging strong plant root systems, keeping soil cool, improving soil structure and, in the case of compost mulch, adding nutrients. Not to mention, a layer of mulch on your garden just looks nice!

How much mulch should I use?

A one- to two-inch layer is most effective with compost, leaves, or sawdust. Two to four inches works best for bark or wood chips.


Portland Water Bureau Saving Water Outdoors

Water Efficient Plants for the Willamette Valley (PDF)

Alliance for Water Efficiency Landscape, Irrigation, and Outdoor Water Use