We love our mulch, don’t we? It can be the eye-pleasing beauty bark or a plain plastic tarp — it doesn’t matter much, because what we’re really after are its practical results: fewer weeds and warm, moist soil. And, show of hands, how many of us have given the odd piece of cardboard a try? It’s cheap, it’s biodegradable, and that brown color matches almost everything — it’s all good, right? Well, has Linda Chalker-Scott got news for you…
I’ve discussed my dislike of cardboard mulch before: like other sheet mulches it restricts water and gas transfer between the soil and atmosphere. In published comparison studies, other mulch choices generally outperform cardboard in terms of plant growth, weed control, etc. But there’s one area where cardboard is tops compared to every other mulch material tested.
Termites LOVE cardboard. Did you know that termite researchers use cardboard feeding stations to lure termites? And cardboard is often used as the “control” in feeding studies, because termites will always eat it?
People seem to think that wood chips are termite magnets. Though termites can eat some types of wood, they prefer cardboard in taste testing. If they are given no choice and have only wood to eat, they will consume it but their survival rate decreases. Dead termites don’t reproduce.
To give termites a bit of a break, they are very useful in bringing life back to crusted, arid soils: studies have shown that just adding mulch and termites to these degraded soils is enough get biological processes going again.
But personally, I’m not providing a cardboard welcome mat for termites to the gardens surrounding my wooden house. Hopefully you won’t either.
Dr. Chalker-Scott is WSU Extension Urban Horticulturist and an Associate Professor in the Department of Horticulture and Landscape Architecture. She is a regular contributor to The Garden Professors blog.