On Wed, Feb 1, 2012 at 9:28 AM, Ken <kjblack@pacbell.net> wrote: > Thank you Tim, Nhu and James for your feedback, > > I generally add no organic material in my seedling mix, which is generally > 1/3 perlite, pumice and DG, Around Seattle, gardeners often use granite chips (available at feed stores, garden centers, stone yards) for seedling top dressing. It seems to help keep the moss down , but not great for keeping Liverwort out of the pots. I've used charcoal chips, and more recently crushed mineral chips( available in garden centers ) which seem to be the most effective in keeping these seed pot invaders in check. For wet, dark winter climates such as ours, mosses , algae , and liverwort are a huge problem for seed pots. Rick K