From the Directors Desk - Mulch: The Good, the Bad, and the Ugly

By Fred Breglia

Plant health care does not begin and end with choos­ing the cor­rect plant for a site. Sev­er­al oth­er fac­tors can ben­e­fit or harm trees and oth­er plants, fac­tors includ­ing nutri­ent and water avail­abil­i­ty, soil pH, and prop­er prun­ing and mulching techniques.

Mulch” refers to mate­r­i­al placed over the soil’s sur­face to main­tain mois­ture and con­trol tem­per­a­ture. Over the long term, mulching also improves soil con­di­tions. It is impor­tant, how­ev­er, to use the prop­er mulching mate­r­i­al and apply mulch cor­rect­ly to gar­ner the ben­e­fits. Oth­er­wise, mulch may have lit­tle or even a neg­a­tive effect.

Organ­ic mulches are com­mon­ly used for mulching a land­scape or gar­den. These mate­ri­als will even­tu­al­ly break down and pro­vide nutri­ents, add organ­ic mat­ter, and improve soil struc­ture. Exam­ples of organ­ic mulch include wood chips, shred­ded bark, pine nee­dles, leaves, cocoa hulls, and com­post mix­es. Depend­ing on cli­mate and microor­gan­isms present in the soil, organ­ic mulches decom­pose at dif­fer­ent rates. The decom­po­si­tion process improves soil qual­i­ty and fertility.

Organ­ic mulches reduce the loss of soil mois­ture through evap­o­ra­tion and insu­late plant roots dur­ing times of tem­per­a­ture fluc­tu­a­tion. Mulching helps to sup­press weed growth and stop the ger­mi­na­tion of wind­blown weed seeds. It inhibits cer­tain plant dis­eases. Aes­thet­i­cal­ly, mulch pro­vides a uni­form look for gar­den beds and helps pre­vent dam­age from weed whack­ers and lawn mowers.

Though ben­e­fi­cial, mulch must be applied prop­er­ly to offer its full spec­trum of ben­e­fits to plants. Too much can actu­al­ly be harm­ful. The cor­rect amount of mulch applied should be between 24” deep but not touch the base of a tree trunk or a plant stem. Deep mulch is often applied as a means to con­trol weeds and reduce main­te­nance, but it might actu­al­ly cre­ate addi­tion­al prob­lems such as root rot, nutri­ent defi­cien­cies, and tox­i­c­i­ty. Deep mulch can also cre­ate a habi­tat for rodents that chew bark and even­tu­al­ly gir­dle trees.

So how do you apply mulch cor­rect­ly in your land­scape or gar­den? To begin, con­sid­er fac­tors such as drainage. If drainage is poor, apply­ing a thin lay­er of wood chip mulch can help absorb excess water, improv­ing soil aer­a­tion as it breaks down. If drainage is ade­quate, apply a 24” lay­er of mulch out as far as the tree’s drip line or beyond if pos­si­ble. Make sure the mulch is not touch­ing the tree trunk but instead is at least 2” from it. Reap­ply mulch as often as need­ed, usu­al­ly once a year.

Mulching can be a plant’s best friend when applied cor­rect­ly — or its worst ene­my when not. Fol­low­ing these guide­lines will ensure health­i­er plants and few­er prob­lems for your grow­ing investment.


Summer 2015

Volume 33 , Number 3

Share this

The Latest from Landis

Aug 06, 2022

Landis Forest 5K - August 6, 2022

A record turnout! Click here to view all the great photos from this event, and... read more

Jun 10, 2022 | Anne Donnelly

Don't Overlook Your Reciprocal Admissions Privilege

A sometimes overlooked benefit of your Landis Arboretum membership is the American Horticultural Society Reciprocal... read more

May 29, 2022

Scenes From the Spring Plant Sale

Thanks to our many wonderful volunteers, plant consignors, vendors, and customers, the Landis Signature Spring... read more

May 28, 2022 | Fred Breglia, Executive Director

From the Director’s Desk: Q&A, Part III

In this last Q&A session, I am focusing on leaf color change during the... read more

May 28, 2022 | Erin McKenna Breglia, Landis Gardener

From the Garden: Milkweeds for Monarchs!

Many people enjoy seeing butterflies in our Landis gardens. especially the monarch butterfly, Danaus... read more

May 28, 2022 | Anita Sanchez

Life and Death on the Lawn

It’s a beautiful summer day. You’ve finished your stack of books from the Landis... read more

News Archive