A Favourite Tool: Black Plastic Bed Covers

More than three decades ago, a coworker, one who also was a vegetable gardener, told of growing his corn through a black plastic sheet.  Using the plastic as a mulch and weed barrier, he had great success keeping the corn warm and weed free with his black plastic 'mulch'.  

I gave it a try.  I bought a roll of 6 mil black plastic, 10 feet wide by 100 feet long and cut it into pieces 5 feet by 12.5 feet.  These comfortably covered a 4 foot by 12.5 foot, 50 square foot bed with room to spare.  That roll gave me 16 bed cover pieces. The plastic turned out to be Silage Cover plastic that was used by the area farmers to cover the open silage ends of their dairy farm's bunker silos.  The stuff was very ultraviolet resistant and has never broken down in the sunlight for these 30 odd years.

Last year's carrot beds just before planting.

Not only did the corn grow weed free – I’ll demonstrate how when I next plant my corn, -- but it was very handy in keeping weeds down in other beds growing the squash and the cabbage families – anywhere the plants spacings were wide enough for regular slits in the reusable plastic.

Last year's corn bed started in black plastic.

My Pacific North West location receives 63 inches of precipitation (mostly rain) per year.  That constant wet from mid-September into mid-May and sometimes June leaches out nutrients from the soil.  Our cloudy, cool, damp springs can let local weeds flourish while our vegetables slow and languish.  Hoeing weeds in the spring when the soil is wet doesn’t work, it just transplants them and that added stress inclines them to go into seed production. (that’s not good).

Black Plastic Bed Covers can keep the rains from leaching nutrients, restrict the sun from growing weeds, and warm the soil earlier than usual. The bed cover can also be used to stunt or kill any winter cover crops like fall rye in a matter of weeks.  

Notice on left bed -- dead fall rye after removing black plastic

The sheets are also good for covering newly manured beds, like the chickens’ run, once the birds have been moved to their next location.  The black plastic helps warm the soil and gives the microbes a head start in processing and readying the new nutrients.

Two beds from old chicken run.

With my yard sitting on top of 200 feet (deep) of gravel, just below my shallow subsoil is a wealth of sand, stones, and rocks (wealth that is if you had a gravel pit).  These Coarse Soil Particles are always trying to get my attention whenever I dig, rake, or turn the soil.  Technically they’re great for drainage and for helping warm up the soil in the spring but my perpetual OCD project is to constantly remove them.  I gather pails of them each year and stack the larger stones in a corner.  These larger rocks I use as temporary anchors for my Black Plastic Bed Covers.

Before covering I like to rake a slight hill along the center of the bed for better runoff into the paths.

When the time to plant arrives I simply pull off my black plastic bed cover and often just fortify, till, rake and plant.  

When Jean-Martin Fortier’s book, “The Market Gardener – A Successful Grower’s Handbook for Small-scale Organic Farming” came out in English in 2014, I was pleased to see that he too recommended the use of black plastic as a weed suppressor.  

I was a bit too proud to hear that I’d been ‘doing it right’ for many years on my much smaller scale garden.  My son TOG hadn’t yet gotten into using that tool on his acre-plus but quickly adopted it as he gradually had the funds to afford larger scale sheets.  He found it to be an initial cost that was well worth it.

My Black Plastic Bed Covers are a tool that I’d have a hard time doing without.  That’s why I invested in a second roll – just in case.

Happy Gardening.