@Lisak1 Four feet deep?! That's a LOT of gravel! Do roots really need that much depth?? I want a bog but I have no where to put it for it to look natural because my pond is raised.
Probably not for the roots, but the first foot or so is actually filled with larger rocks (about baseball sized around the vault and manifold) so the gravel doesn't fill the whole four foot depth. The gravel starts at roughly the 3 foot level if I remember correctly. And yes, it was a LOT of gravel. We had a landscaper with a bobcat here that day doing some other work for us, so we had him move and dump it for us. Otherwise I would still be shoveling!
I know there are opposing opinions about using a bog for filtration, but that's the purpose of ours - it's our only filtration. So if it's not filtering (as some will tell you) then I'm not sure what is, as our pond water is as clear as when it comes out of the hose. Our plants grow like crazy in the bog. I have a clump of irises that needs to be separated this fall - we stare at each other every day, wondering who will win that battle! The roots on those don't generally get all that deep, but they do get heavy! And especially when you add gravel to the mix.
And Larkin gives good advice - consider the effect you want with your bog. At first I just wanted to get things growing in it so I wasn't really careful about what I put where. But it's really another garden bed - you want it to add to your overall effect, not look like a jumble of plants. Also, some plants are real bog bullies (I'm looking at YOU, mini cattails!) and will overtake other plants to the point you will forget they were even there until they timidly poke their heads out again the next spring. So give everyone lots of room to spread out! If I had the space I would have made my bog much longer and wider. It's a fun and different kind of garden area - and biggest bonus... never needs watering!
