Cardboard Mulch

Cardboard makes a great flower bed mulch to kill off unwanted growth. (Photo by Charlotte Ekker Wiggins)

Cardboard Mulch

I’m taking a break from uncovering my latest new flower bed and creating a new one, courtesy of my stash of cardboard. If you garden on a hillside like I do, trying to even establish a new flower bed is a challenge. If you have an area that has established growth, it’s even more of a trial. That’s where my cardboard mulch kicks in.

Instead of using harmful chemicals to get rid of the unwanted growth, I use cardboard. The cardboard keeps the soil underneath moist as it kills off unwanted growth.

This is a cardboard pile that’s been sitting for about a month. (Photo by Charlotte Ekker Wiggins)

Once I establish my new flower bed site and make sure there is nothing growing there I want to keep, I haul my stash of repurposed cardboard to the new flower bed site, scattering the first layer over the new flower bed foot print. As I get more cardboard, I add it to the area, adding rocks to hold it down.

If I’m extra industrious, I will pour shovel fulls of wood mulch on top. If you have grass clippings, you could dump those on the cardboard.

By the time the new flower bed is ready for planting, the dry grass clippings could be incorporated to improve the soil. Make sure the grass is dry; still green grass is very hot and will burn.

Then it’s a matter of ignoring the looks of a cardboard-covered garden area for a couple of months as the cardboard kills off whatever is growing under it.

I do periodically peek underneath. I often find worms moving through the soil, a good indication that the cardboard is keeping the soil inhabitants happy. Birds and butterflies are not the only garden tenants we should cater to, the ones in the soil are what give us the flowers.

When I don’t see anything green anymore, I pile up the cardboard and move it to a new future planting area.

Underneath the cardboard, moist soil ready for planting. (Photo by Charlotte Ekker Wiggins)

The cardboard lasts for about 3 new flower beds depending on the time of year. Early spring and late fall, when we have rain, the cardboard deteriorates faster.

In between, the cardboard holds out longer, even through summer rains. I suspect the heat dries out the cardboard faster.

I have also used cardboard as mulch, then dug a hole through it and planted it. It might be easier to plant something and then surround it with cardboard covered with mulch but I sometimes forget where I have used cardboard to kill off - usually - the vinca ground cover. Vinca is not a native plant but it has been invaluable to hold in my soil on this hillside until I develop the new flower beds.

If you have an area that is being taken over by unwanted plants, such as an iris bed or peonies, try small pieces of cardboard around them covered in mulch. After a few weeks you will find it easier to remove the unwanted plants and you will have both cardboard and mulch handy to keep the area clear of further unwanted guests.

And it will keep your soil moist, which is a huge plus, especially during Missouri’s infamous August dearth.

Charlotte