Septic System Moss

Q: Should I be concerned with moss growing on the weeping bed of our septic system? We’ve lived at our beach property since 1991, and every year the moss takes over a bit more. Other weeping beds in our area don’t have this problem. The tank has just been cleaned and inspected, and the septic guy didn’t know what to make of the moss.

A: The moss you're seeing isn't an indication of problems with your septic system, so you can breathe easy. That said, there are reasons you might consider encouraging the growth of grass instead. Moss doesn't look terrific on a lawn, and grass does a better job of helping water to evaporate from the weeping bed. Moss moves into areas where soil has become acidic, especially if those areas are shady. But since most septic beds aren’t near large trees, your situation is probably tied more directly with soil acidity alone. And in this case, agricultural lime is the cure. It's nothing more than pulverized limestone, so it’s quite safe to use. It also works well to buffer those acid conditions that favour moss growth. Three or four 20 kg bags will be plenty to do most weeping beds. There's no need to incorporate the lime, just dump some in a wheelbarrow, broadcast it evenly with a shovel and wait. It will take time for grass to reestablish itself, but you can aid the process by spreading grass seed. My favourite sowing time is in March, just as the spring is emerging. Sprinkle the seed on the snow, then let frost and rainwater work it into the soil naturally. This approach boosts germination rates considerably.