I am getting ready to build my raised bed veggie garden, but the timber we have has set out in the weather for a while and is really wet and has this white fluffy "moss" on it. Should i clean it off (and so how?) or will my seeds be ok and not clean it. it's going to be a big bed....2ft. high 3ft. long and 8ft. wide.... i specifically want it this way because i want plunty of soil area sence our back yard does not drain and to keep the dog out of it.