Brown snails are an invasive non-native species in California. Everyone complains about them in their gardens. They poison them, step on them, even salt them. They were imported here as a food species, but they escaped and have been a problem in local gardens ever since.
They are a problem because most people water too much and grow non-native plants that snails have a taste for. When you try to grow an English garden in a Mediterranean climate you are creating a smorgasbord for brown snails.
When we first moved into our house the entire front yard was African daisies. In the spring and summer the slope was a beautiful array of purple and white. But, the African daisies were filled with snails and sow bugs. At night the snails would venture out from the daisies and devour everything else in the yard. The first couple of times I tried to grow vegetables, everything was eaten by snails.
We tried trapping them in beer, poisoning them with bait, even copper-covered stripping around plants we wanted to protect. The bait was probably the worst part because it was bad for other species as well. Of course the poison bait never worked completely and the subsequent generations seemed to tolerate it more and more, until it was useless.
Finally, I got disgusted. The hillside was eroding under the tangled vines. An area of African daisies died back, because of the snails, and I tore them out. In that small area we planted some native plants. We mulched these plants with bark and an amazing thing happened–the snails left that area and the biodiversity began to increase.
We stopped using poisonous bait and an alligator lizard moved in and started eating the snails.
Now our native Douglas iris are beautiful, drought tolerant, homes for a variety of native insects, they hold the soil, and there are no snails.
My Gardening with Intent action this week is to decide which section of African daisy I am removing next and what native species I will use to replant.