Expert: Mike Mascio - 4/19/2008

Question
I have small chips (but they are plentiful) of natural coal in a section of my yard where I would like to try planting a vegetable garden.  Is this dangerous or toxic?

Answer
Lynne, unless you plan on renovating that section by digging out the old soil and replacing it with organic materials, I would not plant in that area.

Besides toxicity of coal, a subject in which I am not an expert, I do know that coal has an adverse effect on the ph level of the soil. PH is the formula used to measure the acidity level of soil. The ideal level is 7.0, which is considered neutral. Coal chips will lower the ph to below 6.0, and possibly even lower if the concentration of chips is high. At this level, very few plants will survive.

Hopefully, you have another section in the yard that gets full sunlight. If so, I would suggest building a raised bed of at least 8" in depth. Fill the bed with organic matter such as peat, compost, and aged manure. Frame the bed with 2"X10" cedar planks. Cedar resists rotting. This should provide you with an excellent foundation for a new vegetable bed.

I hope this answered your question. Please write again if I can ever be of assistance.

Regards,

Mike