I have a small (less than 100 sq ft) indoor atrium which we have had for 18 years......the soil is covered with I was told when we did this that the wood chips on top of the soil have to be sterile.....We have never had any bugs........The soil has sunk over the years and I want to ad more wood chips.......do they have to be sterile......if yes where do you get sterile wood chips.......I have searched everywhere..HELP
