Hi all, I am planning on planting some small conifer seedlings in a pot outside. Would it hurt the trees to use topsoil? Thanks.
No don't use topsoil.
Plants, especially conifers, in containers need very good drainage like you get with Al's 5-1-1 bark based recipe.
See this [link to the container gardening forum[(https://www.houzz.com/discussions/recipe-for-5-1-1-mix-dsvw-vd~3070255?n=7) for more info.