Slugs! Hi I'm new to this site.

Hi there, I am new to this site and quite an inexperienced gardener so please bear with me. I hope I have posted this in the right place!

I have a small garden and this year is the first year I have planted it out with anything at all. I love bedding plants and at my old house had good success with busy lizzies and petunias. I set about planting my beds with busy lizzies and marigold only to find that we have a very large population of slugs! We also have a resident hedgehog who I understand is excellent for keeping slugs down but there are so many I don't think he can keep up! our next door garden is an overgrown wildernesse and a slug heaven, I have seriously never seen so many slugs! I can't use most types of slug killers for fear of them not being safe for the hedgehog. We have tried beer traps which are wonderful but still I am struggling. I have already lost my marigolds completely and the busy lizzies were fighting back but are clearly now really struggling.

I want to replant my beds with something else, what can I use that slugs won't eat and can now be planted in mid July? I have some geraniums in a tub and they are doing handsomely and do not appear to have any slug damage. So I hoping to maybe plant some of these out with something else but I need some advise.

Thank you for listening...

Iron phosphate: non-toxic