CP Bog: run-of or groundwater from drainage introduce +nutrients?
I'm working on creating a small garden for cranberries, sundews, and purple pitcher plants.
I just dug a 4' x 5' x 2' deep hole in my yard (full-sun) and placed into the hole a 45 mil. epdm rubber liner. Then I filled it with peat and construction sand. I did not perforate the rubber liner as some have recommended for drainage.
1. I'm concerned that if I don't keep the lip of the liner's edge above the surrounding ground-level, rain run-off entering into the "bog garden" will bring with it a significant amount of accumulating nutrients over time.
2. Due to rock in the ground, when it rains heavily, the soil in the yard retains groundwater. If I were to perforate the liner, I suppose the nutrient-rich ground water would enter into the bog and, as I understand, purple pitcher plants will not thrive when the bog garden contains nutrients; yet from what I've seen in nature, they thrive on the edge of acidic ponds (which must have a good amount of nutrients.