I have a bog area I added to my pond. It is not the hard plastic type. I used the rubber liner when I built my pond. It is guaranteed for at least 20 years. Anyway the bog area is sort of a separate area. It is dug low enough that a small amount of the pond water (when really full) can spill over into it. I lined the area with the rubber liner then added pea gravel then my soil. It keeps the soil really wet and the water stands more in the pea gravel underneath. The plants in a bog area usually like really wet soil but not to be standing in water. A lot of the online sites that sell pond plants also carry bog plants. I ordered some on line. It has been 5 or so years ago now but I remember I did order some plants from Pond Megastore
https://www.pondmegastore.com/.... I Know I am a little late posting but hope this helps some.
