How deep should my Bog [Marsh] Garden Be?
I'm building a 32 x 21 large linned garden pond with a 3' wide strip of linned bog surrounding the entire circumfr. of the pond. How deep should I make the escavation that will be linned with EPDM liner and back filled with soil; will be growing irises, watercress, and other marginals in the soil. NOTE: I live in Zone 6b and this past winter, I had a small kiddy-pool filled. with only 6" of soil and had irises, water calla, water cress, forgetmenots, cardinal flower, and other flowers in the shallow 6" of soil and not only did they thrive densely all last growing season but they all made it through the winter, having been frozen solid in moist soil. This leads me to believe that I do not NEED the suggested 2 feet of depth for a margin marsh-bog; i'm thinking that 12" would be sufficient for more marginal's root systems and for the purpose of overwintering. Please, give insight - thank you.