Can I use Fedex and UPS boxes for mulching?
February 17, 2012 8:50 AM   Subscribe

Can I use any cardboard, such as Fedex and UPS boxes, for mulching?

I heard that we should stay away from glossy papers for mulching and composting due to the ink. Is there similar restriction for cardboard? I have a stack of Fedex and UPS boxes and I'm wondering if I can use them.

Bonus question: how long does it take to fully decompose a cardboard box laid flat on the ground? I live in the Seattle area.
posted by 7life to Home & Garden (10 answers total)
examine the boxes carefully for a notice on the inks...'printed with soy inks' or might need to pull the box apart and look under the overlaps (where the color squares and registration marks are)...not seeing a notice is prob not a good sign.

looking for free boxes? check behind the grocery/convience store...there will be more than you can possibly use...

flat on the ground is not the best/fastest way to break it down...soak in water, tear into chunks (the smaller the better) and compost with leaves/dirt/etc...
posted by sexyrobot at 9:02 AM on February 17, 2012

Do you mean corrugated cardboard? I wouldn't. Cardboard is a chemical-processed pulp paper product, and uses adhesives to build the surface-corrugation-surface laminate structure.
posted by Thorzdad at 9:04 AM on February 17, 2012

I dont know about the inks specifically, but from my work at a coated board (think cereal boxes, one side brown, one side white-to-be-printed on) producing plant there shouldn't be any harm from the white side since it is mostly a type of clay.

Consider where it's going anyway, to a landfill? You're just accelerating things then, no harm no foul.
posted by RolandOfEld at 9:25 AM on February 17, 2012

I'm assuming you mean mulching for use in a garden, yes?
posted by Thorzdad at 9:32 AM on February 17, 2012

Response by poster: Thorzad - yes. At this point I'm trying to use it for weed control in overgrown areas. Which will be the future site of my garden beds.
posted by 7life at 9:38 AM on February 17, 2012

Some people might differentiate between the needs for a flower garden and vegetable garden by the way so that information might be useful.

Honestly, I see this as pretty low on the totem pole with regards to 'risk factors' in your home garden (even if it is for food production), doubly so when compared to pretty much anything you buy in the store that isn't local, uber-consciously produced. For example, knowing the history of the site, going back years and years, can be even more instrumental with regards to obtaining an USDA organic certification at least here in the South where cotton farming was so widespread for so long.

Hope that wasn't too much of a derail, I'm just saying that the more people know about your intended use case and your moral/eating preferences, the more they can help advise you.
posted by RolandOfEld at 9:45 AM on February 17, 2012

Cardboard is used all the time for sheet mulching. As others point out, depending on your standards, ink, adhesives, etc in the cardboard could be problematic for you. I suspect they are a very, very small risk, environmentally speaking.
posted by that's candlepin at 10:40 AM on February 17, 2012

Inks used for printing just aren't that toxic to begin with. Most places use soy-based inks now, anyway. Anecdotally, I have been using boxes from UPS, USPS, FedEx, Amazon - anything that comes my way - as mulching for years, and we're all fine out here.

A worse problem is one which is specific to our climate. (I live in Skagit county). Any sort of solid mulch will create a slug haven. Slugs particularly like cardboard, because it gets nice and dampish and mildewy. Oh how they like it.

Cardboard mulch means that the slugs can just hang out right there, instead of having to commute all that way from their usual hideouts. These days I only use cardboard (under weed cloth and then bark mulch) for paths and garden areas where slugs aren't a problem, like the area around my star magnolia.

It usually lasts about a year. Maybe two, if I have put down several layers, and used weed cloth and bark mulch too.
posted by ErikaB at 4:41 PM on February 17, 2012

Bonus question: how long does it take to fully decompose a cardboard box laid flat on the ground? I live in the Seattle area.

Decomposition depends on temperature, moisture, aeration, and the presence of decomposers. So it is really hard to say. However, I can tell you that the faster it decomposes, the more likely it is to create a nitrogen deficit (immobilization) in the soil. Cardboard has an extremely high carbon to nitrogen ratio (300-500:1, ideal for decomposition is 24:1), such that the microorganisms that decompose it take nitrogen from the soil in order to do so. This is because these microorganisms utilize nitrogen in order to break down the cardboard, so plants grown where cardboard is breaking down can easily suffer from nitrogen deficiency. This nitrogen deficit can also create a positive feedback where microbial breakdown of cardboard slows due to low levels of nitrogen.
posted by oneirodynia at 8:04 PM on February 17, 2012

If the ink is biodegradable. I guess you can.
posted by BobS13 at 2:40 AM on February 18, 2012

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