Mulching Your Plants—What is Best?

Recent articles have prompted questions from some of our clients about mulches for their landscapes. Indeed, there is such a variety of mulches on the market today, that some confusion is bound to arise concerning their use. While there are a myriad of technical issues (i.e., boring issues) relating to mulch, overall it can be said that mulch generally helps conserve moisture, buffer erosion from rain and irrigation, and inhibit weed proliferation. And by and large, you should use what looks good to you in the landscape; some products will last longer and stay in place better than others, and some products are better for the soil structure than others. But most people just want their flower and landscape beds to look nice, and the mulch you choose will probably fill that requirement. We would like to clear up a few cloudy issues, however, using our 40 odd years of experience as a guide.

Cypress and cedar mulch, contrary to recent statements, are not particularly attractive to insects—in fact, both have tiny amounts of chemicals that deter insect activity and slow degradation; also, neither product adds much in the way of nutrients to the soil because they do, in fact, degrade slower than most mulches. Pine needles, or pine straw, is a popular mulch in the South because that’s what they have in the south—pine trees. In the Kansas City area, we are in the midst of the Ozark plateau and our forests are primarily oak and hickory—hence, we have primarily oak based mulches readily available. Oh, and by the way, pine needles do very little in the way of lowering the pH of the soil. Cocoa hulls have been mentioned lately as a newly popular mulch, and while it is true this product is uniform in appearance and does smell good to chocolate lovers, it has some hidden and rather unappealing drawbacks. Because cocoa hulls are so rich in organic materials, it is very attractive to insects of all kinds. Fungus gnats are quite a problem in cocoa hulls, and for some reason unknown to us, flies love to lay their eggs in this product and you can often find maggots in large numbers crawling through cocoa hulls. These hulls tend to be rather slick and slimy under the relatively dry top layer, and can be a hazard to walk across if you are unaware. On top of all these drawbacks, cocoa hulls presents the same toxicity hazards to your pet as other chocolate products.  Rubber mulches are sometimes presented as a good option; our opinion is this: putting copious amounts of anything that has been in contact with road chemicals for its lifespan, and adds nothing of benefit to the living, breathing soil is probably not a good idea.

We like to use mulch products that both look nice and provide some benefit to the soil. Cotton burr compost products enrich the soil and have a dark brown, uniform appearance, which makes for a desirable mulch. They do however have a strong “aroma” when first applied, so they might not be the best choice if you are having an outdoor dinner party the evening following application. Fine pine bark and pine bark soil conditioning products make excellent mulches and since they are softwood products, they degrade fairly quickly, adding texture and some nutrients to the soil. A word of caution, though, since they are lightweight, they can “float” during heavy rains or on steep slopes. Finely ground oak and hardwood products are plentiful, relatively inexpensive, and hold the ground quite well. Its texture and consistency allow this product to “knit together” and hold slopes in place, and if it is finely shredded, it breaks down to add tilth to the soil. Hardwood mulches do lose their rich, dark color over time though, and need to be replenished occasionally to look their best.

Finally, a word about artificially colored mulches. In lower maintenance gardens or where property owners can’t mulch regularly, they offer a pleasing appearance for long periods of time. When installing, caution should be used when applying around concrete or other surfaces that might be stained by the product’s dyes.

Remember, Greenleaf offers a full array of mulch products to add beauty and functionality to your garden. Our crews can give your tired landscape a quick mulch makeover so you can just sit back and enjoy the view! Happy gardening!


Contributing editor: Don Archer, Don Archer Designs in partnership with Greenleaf Garden Services