There is a simple answer and that is not to grow them as they will continue to cause you a problem. I love Heucheras and used to grow them in the garden, (not in containers) but they were destroyed by Vine Weevil so I gave up growing them and looked to plants that they didn't like.

There was something on TV a while back from the National collection of Hostas. They spray the plants with Garlic water and that is supposed to deter molluscs.
https://www.siennahosta.co.uk/blogs/news/garlic-wash-slug-control
Check that out.

My Hostas are all in pots and have had no slug damage since putting a layer of coffee grounds, from the local coffee shop, on top of the soil.

Thanks for your input folks, much appreciated.