I'm thinking aboout putting long, narrow trays completely around my pond and filling them with soil and river pebbles 3/8" over them so that 1. I can have some dirt in the pond, but isolated and 2. so that I can easily remove and clean the substrates. Would the plastic bottom of the container resting upon the rubber liner create significant conditions whereupon anaerobic bacteria in cultivated in great numbers between the plastic and rubber - i doubt it.


MORE importantly, to cover the holes in the container can i expect that cloth will hold up for long

I don't expect much would occur in the tiny space between the plastic trays and the liner. It sounds like an interesting idea. Let us know how it works out! Some people have bog areas next to the pond filled with dirt and/or gravel but the trays sound easier to clean if you can integrate them into the pond design. Be sure the trays either are tough or you only plant docile plants in there. By that, I mean things like yellow flag iris and common cattails bust right through the regular Lerio pots I have in my pond after a single season. The roots are very strong.

To cover the holes, you have a few choices. You can cover them with burlap, panty hose, or nylon aquarium/pond filter bags. Hold that down with a thin layer of gravel before adding in the dirt. The burlap is pretty tough but may let some dirt through over time. The panty hose and filter bags tend to shift over time and slowly degrade or get holes in them. Or you can seal them with aquarium silicon or putty before doing anything else to them. Or, you can try to find trays without holes. I have a plastic window box that didn't have holes in it (we had to drill some) that we used for terrestrial plants (nothing to do with the pond).

2 questions...

I can use extra pond liner - however, will there be a lot of anaerobic...? how deep should the substate be and ratio of soil to gravel.

if the pots are wide, will the irises still break the pots you are talking of?>

I'm not sure what you're asking about the anaerobic bacteria and liner. For a general sort of bog, you might put in 4-5" of soil topped with 1.5-2" of gravel. If you go the just pea gravel route (no dirt), then 4-6" of that.

Iris are less likely to break through larger pots. Most of my iris are pretty well behaved. It's the yellow flag iris that grows like mad! It's a monster in my ponds! One I have in a 4 gallon container I think that I repotted fall of 2002 is now taking up about a 4' x 4' area of the pond! I don't know how in the world I will get it out for the scheduled repotting next month! I can't even find the pot. I'll have to saw it out in chunks! It's too thick to cut with regular garden cutters and too heavy to lift intact! You might want to avoid that kind of iris if you want things under control. My blue flag and purple and red iris were must slower growers. My poor red was so slow that it died.

will the yellow variety of iris ever damage the liner with its tuber/roots? especially if grown in pea gravel directly in the pond

Yes, it's possible. I'm worried that a batch of yellow flag iris that self-seeded in my overflow (gravel over liner) could puncture so I keep cutting it down, and it keeps growing right on back!