JJ,

OXYGEN! Many marginals like a constant supply of moisture. Not to be sitting in water. Major difference will be that moist soil, or even running water will have oxygen available to the roots, a wading pool, especially in hot weather will have none. I have had the same with ligularia, thought it could stand in water, but it didn't, simply rotted away.

Lots of plants, if placed in deep pots and half submerged in water, ie half way up the put will terminate their roots at the water level, after 6 months if you knock the plant out the pot, it will look like it has been in a shallow pot with no roots going down to the bottom. The plant has nevertheless been in constant moisture. Others like the candlearbre primulas will send their roots out through the bottom of the pot and be perfectly happy with white roots lying fully underwater, you need to experiment as this will tell you the conditions in which to eventually plant your plants once you have your bog.

Sit your pots in a tray with 1/2" of water only in the base. Those that put their roots out to get more water will survive and probably relish being planted with their crowns closer to the water level. Those that show stunted rotting root at the base of the pot obviously want to be planted higher where they can reach the moisture without being in it. Meanwhile, you shouldn't lose the plant as it will still be living off it's roots in the pot above the water level.

Some plants also take seasonal flooding, interesting to note whether this is in the growing season, or in the dormant one. The classic for this is the Japanese ensata iris where in growth in the paddy fields it is flooded while in winter it has relative dryness. Others get "moved about" by floods while dormant, and set up new colonies when the floods recede.

Happy planting, Greenmanplants

Thank you for the good info, Greenman. It is much appreciated!

To anyone: Still wondering where the "water-table" is in a bog. Seems to me that muck would be anaerobic; how are you able to create aerated soil in a bog situation?

Jim, here's a good site which I've found helpful. Lilypons has been in the aquatics business for decades...when they say something I've found it to be "spot-on". They recommend like Greenman's post that you start off at just minimum water depth and proceed to lower gradually to maximum recommended depth for a particular plant. They have most of your plants probably so you can check for each.

They have a good section on bog construction as well (site is a little frustrating to navigate...I'm going to order catalog!). Seems it's not necessary to provide drainage...something I hadn't yet made up my mind about. Anyway, I have just pond now, but intend building bog for many plants now in individual containers. In our GA heat, anything that doesn't need watering every day is a winner! josh

Here is a link that might be useful: Bog Plants

we do it that hard way. We fill up the kiddy pool with pea gravel and dirt (stacked high), fill the pool up with water until it looks like soup and just stuff the plants into the muck. The problem is the pots. The pots don't allow anything to circulate.

I'm growing several varieties of Cyperus, Scirpus, Equisetum, Canna, Colocasia, Carex, Acorus, all in individual clay pots sitting in deep (2 to 4 inch) trays or saucers of water. All doing fine. I water from the top and refill the bottom container every other day. On really hot days the bottom container is dry...these plants really love water!
I was growing a Canna 'Pretoria' last year in a 16" plastic pot in a pool, about 10" deep. In the Fall it looked so good I decided to bring it inside for a few weeks, thinking it would soon die back. To my amazement it continued to look good all winter, even putting up new stalks, just sitting in a 2 "deep saucer of water. I watered from top regularly, too. It just adapted amazingly well!

A couple of weeks ago I removed a potted Black Taro, Colocasia esculenta 'Black Magic", from that same 10" deep pool, to adapt it to drier soil since I'll be taking it inside this Fall. Lost a few leaves but it seems okay so far. I'm keeping it watered well.

This is just how these particular plants have done for me. I've not grown Ligularia,Eupatorium or Iris.
It may be that sitting in a few inches of water that sometimes dries out is like a muddy bank...my particular plants don't really need more than that. I'm rethinking building a bog...lol. josh