From the Garden - Gardening with Paper Mulch: Making of a Horticultural Myth

When I first start­ed gar­den­ing at Lan­dis, I was intro­duced to many tools, plants — and ideas. Every gar­den­er, it seems, had a dif­fer­ent opin­ion on what to cut back and what to retain, when to plant and when to divide, even what to wear. It was gloves, sun­block, hats, and long sleeves for some; for oth­ers, shorts and tees.

One of the first ​“tips of the trade” I was intro­duced to was smoth­er­ing weeds with paper prod­ucts. In the Van Love­land Peren­ni­al Gar­dens, where a vari­ety of shrubs, flow­ers, and bulbs are plant­ed, weed fab­ric was not an option. Instead, news­pa­per became this gardener’s new best friend. The near­by My Shop­per office was will­ing to donate reams of back issues. I would put down a thick lay­er of paper, then a lay­er of com­post or mulch, and then water thor­ough­ly. The site would remain weed free for at least a few weeks, and the news­pa­per would com­post back to the earth before the next spring’s growth. The process felt clean and sus­tain­able. We even used card­board in larg­er open areas, such as around new­ly plant­ed woody plant col­lec­tions. In time, the weeds, espe­cial­ly the Aegopodi­um poda­graria (bishop’s weed) and the grass, always came back. We also noticed a loss of many plants, such as Cal­i­for­nia pop­py, tall ver­be­na, bor­age, even batchelor’s but­tons, that should self-seed every year. We thought it must be wildlife snack­ing a bit too often .…

At this same time, I was work­ing on my intern­ship and under­took a small gar­den project around the old well pump in front of the Farm­house, using a very dif­fer­ent approach. I out­lined a gar­den oval of about 12 feet and scalped the exist­ing grass with a string trim­mer as far down to the ground as pos­si­ble. Instead of using paper or card­board, I cov­ered the new bed with about 12” inch­es of nat­u­ral­ly mulched wood chips donat­ed by the local elec­tric com­pa­ny. I dug a few holes in the mulch and plant­ed the bed. Even over sev­er­al years, the ​“well pump gar­den” bed did not become infest­ed with weeds, and the grass nev­er came back. The phlox, columbine, and daylily con­tin­ue to thrive. 

Recent­ly, I learned about the tox­i­c­i­ty of using card­board in the gar­den, espe­cial­ly where food crops are involved. The card­board pro­duced for ship­ping today is treat­ed to be water­proof or water resis­tant and breaks down very slow­ly, leach­ing chem­i­cals into the soil. These chem­i­cals are not the type you would pur­pose­ly put into your gar­den as they can kill and effec­tive­ly ster­il­ize the exist­ing soil matrix. Stud­ies have also proven that card­board mulch doesn’t work as well as sim­ply dump­ing at least 12” of clean nat­ur­al undyed wood chips (some­times called ​“arborist chips,” some­times ​“play­ground chips”) onto the soil to deter weeds. These chips do break down over time, feed­ing the gar­den bed rather than destroy­ing the exist­ing ecosys­tem. Card­board mulch can also pro­vide habi­tat for pests such as ter­mites and slugs. Card­board may keep a wet site too wet, lim­it­ing ben­e­fi­cial air and water exchange. Some­times water will run off card­board rather than per­me­ate through it. 

Pos­i­tive attrib­ut­es of this type of gar­den­ing include high­er pro­duc­tion yields, reduced soil ero­sion, bet­ter aer­a­tion, and over­all health­i­er soil. The process of smoth­er­ing weeds with wood chips is less time con­sum­ing as well.

Gar­den­ers learn through expe­ri­ence. As prod­ucts and envi­ron­ments change, we must be will­ing to adapt. As gar­dens grow, we need to lean in clos­er to observe them. In doing so, we can gain greater wis­dom, and both we and the plants we tend will be health­i­er for it.