Mulch Obliged

Many of the trucks belonging to Sawdust Supply, one of Kaleidoscope’s preferred providers of landscape products, have a trendy slogan printed on them: “Bark now, or forever hoe your weeds.”

The slogan mentions bark specifically, but this is just one of many different types of mulch on the market. Some are made from recycled yard trimmings, or composted animal manure. Others come from the bark of trees, or from pieces of branch and trunk wood. Many proprietary mulch products contain a specific blend of these materials.

It’s old news that mulch is good for the garden. At least, it’s old news for those in the horticultural industry and those industrious folks who spend their weekend hours puttering around their gardens. Nearly every type of mulch, if properly applied, keeps weeds down and gives garden beds a uniform, tidy appearance that many associate with a well-kept garden.

What’s not as well-understood are the myriad soil-building benefits of mulch. In addition to keeping the invasive plants away, quality mulch products improve the health of desirable flora.

A wide variety of serious issues plague gardens in the greater Seattle area. Chief among them: compacted soil. Put simply, this means the soil has compressed over time, leaving less room for air and water.

Many factors (foot traffic, construction equipment, etc.) can cause this but the results are similar: compaction limits the ground's ability to hold water, which isn’t good news for the plants trying to use that water to grow. photosynthesis, the process whereby plants absorb sunlight and convert it into energy to fuel their growth, cannot occur without an ample water supply.

But water isn’t the only thing plants need to survive. Just like people, plants need a variety of nutrients and minerals to grow and prosper. Roots uptake these nutrients, along with water, from the soil.

Many of these nutrients are made available to plants through the decomposition of organic matter in the soil. Bacteria, fungi, and other microorganisms feed on the organic material, and plant nutrients like Nitrogen, phosphorous, potassium, and many others are produced because of those digestive processes.

As these digestive processes occur year after year, the organic content of the soil diminishes. If it isn’t replenished occasionally, soil organism activity falls off, and plants have fewer nutrients. Fertilizing can help alleviate this to some degree, but It’s no substitute for natural soil processes.

Here’s the good news: laying down a 2"- 6" layer of mulch reduces soil compaction, replenishes reserves of organic material, suppresses weeds, and makes any yard look amazing. That’s a lot of ecological and aesthetic bang for your buck.

Coarse woody mulches, like arborist chips (chopped up pieces of tree branches and logs) are extra effective. Plus, they last longer!

Don’t just take our word for it. A recent study conducted by Bryant C. Scharenbroch and Gary W. Watson for the International Society of Arboriculture found that both compost and arborist chips improved the health of birch and maple trees planted in compacted soil, with arborist chips prompting a slightly better growth response. To view a PDF of the study, follow the link in this blog post. If you’d like to purchase a physical copy of the study to impress your gardener compatriots, follow this link to the ISA website.

After you’ve done the due diligence, consider hiring Kaleidoscope to mulch your property! One of our expert horticulturalists would be happy to visit your site free of charge, assess the quality of your soil, and discuss which mulch product is most suitable for your unique landscape. 

by Joseph Sutton-Holcomb, Account Manager and Certified Professional Horticulturist