In my experience almost all problems are fixed with compost. Too much rain, it drains well. Its is nutritious for the plants and it makes keeping weeds out easier. I use slug bait for the slugs and use it a few times a year for a few years and they will be gone. I don't use pesticides regular, but I do use them if I actually have an invasion I can't get rid of otherwise. There are some organic/green type of things you can try like garlic spray, neem oil based sprays or some swear by mouthwash. ect. In my experience if you do nothing to control the critters or improve the soil, (which most soil usually needs improved) then the garden will fail. I also use Preen, and occasional Round up-with spot application. (killed poison ivy that way, can't get near the stuff!)
