It’s not that easy being green

Kermit’s right…it’s not that easy being green! Yesterday we noticed that the mulch we put around our organic raised bed garden last Saturday had turned every blade of grass it touched a very dead shade of beige. What made matters even worse…we had used mulch under each bed to level it. Had we just poisoned all the organic soil mix in our beds?

We bought the mulch from a very nice man down the road, so I went by to tell him about our problem to see if he had any ideas about what was happening. My concern was that it might be made from some toxic wood, like old pressure treated wood, and would ruin our organic garden.

It seems that the mulch wasn’t quite ready. He could tell by the smell of it that it was still in a stage of fermentation that would make it likely to kill vegetation. A few days and some rain should solve the problem he thought. The mulch came from the bark of trees about to be cut at a nearby saw mill so we don’t have to worry about treated wood.

We’re new at this and are learning as we go…this time the hard way. We’re hoping that it was not a mistake to put the mulch under our raised beds. We ran out of time last weekend, but our plan is to cover the whole fenced in area with mulch and use containers to grow more veggies and flowers around the perimeter.

We’d love to hear from you experienced organic gardeners out there. Do you think our mulch is safe?

We may have found the answer to our problem…

This is from the Clemson website:

Mulch Toxicity: Though mulch benefits plants, “sour” mulch can quickly damage plant tissue and lower the soil pH causing injury or death. Bedding and low-growing woody plants are most easily damaged. Symptoms include yellowing of the leaf margins, scorching or dropping of leaves and occasionally entire plant death. Although it may be several days before symptoms appear, spreading sour mulch can damage plants immediately.

Sour or “acid” mulch is caused by poor handling or storing of mulch resulting in anaerobic (without air) conditions. Mulch piles need to “breathe” to prevent anaerobic conditions from occurring. In the absence of air, microbes in the mulch (mostly bacteria) produce toxic substances such as methanol, acetic acid, ammonia gas, and hydrogen sulfide gas.

Sour mulch smells like vinegar, ammonia, sulfur or silage. Good mulch smells like freshly cut wood or has the earthy smell of a good garden soil. Another way to determine if mulch is sour is to test its pH. Toxic mulch will have a pH of 1.8 to 2.5.

To prevent mulch from turning sour or to cure sour mulch, you need to turn your pile once or twice a month, more frequently if the pile is very wet. Do not let the pile get larger than 4 feet thick in any dimension if you are not turning the pile regularly. A good aeration will eliminate the toxic compounds in 24 hours, but to be safe allow three days.

For more info on mulch go to http://hgic.clemson.edu/factsheets/hgic1604.htm