I am a newbie at bogs but I did nothing with my first bog, a soil and peat mound inside a pond, I just let nature take its course. The mound rises to, at most, 1" above water level so the ground is saturated. Yellow flag Iris, common and curly rushes survived, in fact I dont rememeber any non annual that didnt except
a) lobellia cardinalis (victoria) but it seems debatable if that is a bog plant and
b) Marsh St John's wort
besides I have yet to overwinter either of those whereever they are.

I just have two questions, was there any water on top of the soil or was it just saturated? It would seem to me since you don't have it created by runoff, rather by capillary action, it wouldn't have the water on top. My instinct is to not have any standing water on it, but to water it occasionally by adding more water.
Second, I would LOVE to see a picture of a bog in the center of a pond. Is it a natural pond? Must be a large one. Do you have any photos that you can post? Oh, I guess that there were more than two questions...LOL!
Lesley

No standing water, just saturated soil and peat. The pond is me made, and probably 12' x 12'
This is the pond just filled
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If you turn up your brightness and contrast you may be able to see the near corner is esstentially a 6" - 9" deep shelf/bay, the bog went in this bay.

This is the view from the opposite corner looking back towards where the bog will be
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Because of the folds in the liner on the floor of the bay I covered the bay with a sheet of plastic, the soil/peat mixture went on top of that plastic,
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The soil was covered in a hessien 'blanket' and plants were planted through holes cut in the hessien, the 'soil' dug out through these holes was scattered on the surface of the hessien. The idea being that the hessien would hold the 'soil' together until the plant roots bound it together
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Note the bog is surrounded by water in an attempt to stop slugs getting onto the bog and at the lobellia. The moat is actually two streams fed from a 'spring' in the very corner of the pond, the streams have been gravel lined since that photo.
I am afraid I dont have any photos from this year that show the bog clearly, the intention was for every thing to blend and look natural, that has happened, perhaps too well, so this is the best photo I have, the bog is in the far right
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Thank you for posting those photos. What am amazing piece of work you have done! What are the yellow flowers all around? It does look very natural and wild.
Lesley

Marsh marigold, Caltha palustris in the extreme left, upper and lower,
Lesser spearwort, Ranunculus flammula in the lower centre and right,
Golden buttons, Cotula coronopifolia, middle right to upper middle right.
It looks like there are blue water forget me nots in the bog, ironically I forgot about those, the large Iris clumps are yellow flag.

Beautiful work. Thank you for posting those photos. It looks so healthy. Hope to have something half as good one day