Being in a similar cold zone, you need hardy ones that will survive your winter or it will be a very costly experience. I've had mixed results with overwintering tropicals indoors. I would suggest the standard "tried and proven" hardy water plants such as: marsh marigold, variegated parsley plant (can't think of it's real name), iris, flag, creeping jenny, corkscrew rush, hardy water lilies, some shorter grasses, etc. I still enjoy the tropicals though like Hibiscus "Moy Grande", Canna, Thalia, Umbrella Palm, Dwarf Papyrus, Bog Lily, Arrowhead and Purple Taro. You need a good mix of both. I love the water plant Lemon Bacopa (not to be confused with the typical annual you see in nurseries). The fish loved playing in it. And don't forget submerged plants. You need lots of water lilies as a protection from predators and sun. You need submerged plants also. They also provide a place for the fish to hide. The first year we put in hornswort we got lots of baby fish. Parrot's Feather is great, too. It's a submerged tender plant, but you can bring divide it easily throughout the season for more plants. The fish like to eat it. The hornswort will overwinter in the pond as will the hardy water lilies. I recommend the book "Encyclopedia of Water Garden Plants" by Greg Speichert (for when you get home). It has lots of pictures and good info on plants - for both in and outside your pond. There are too many too mention here. Enjoy your vacation!

I have a spot which sounds very similar to yours, without the woods behind. The mower marks, poor grass growing, weeds, puddles of water, & the consistent wetness are/were exactly the same. In my case it was a man-made depression to handle run-off from 6 houses in my subdivision to a large drain located in the corner of my back yard. There is a 2nd drain just outside my property by a few inches on the other side for the houses on that side to drain into. My yard is quite sloped side to side and front to back with a bit of extra dropoff just before the drain area. There was no possibility of raising the elevation or using the lasagna method. Here's what we did. We left the lowest part alone, except for digging out a bit here and there to direct the flow a bit. We added some gravel, some 2 inch egg rock, and a few semi-big rocks to make it more attractive, making a sort of dry creek, which isn't all that dry. This rock/gravel area also serves as a pathway through the area when it's dry enough. We added a couple of smaller sideways gravel paths so we can get in and work in the area as well. These don't actually handle water, but they look like they could & we tried to keep them as natural looking as possible by meandering the paths a bit and putting rocks at strategic points. We also have a few areas where we use large flat rocks for crossing. Any green stuff that intrudes into this area is cleared out by using Round-up once or twice a year. This area is a really small portion of the whole & we tried to keep it as small as possible (narrow paths etc.) & quite simple (Round-up) because rock hauling & weed removal from rocks is for people much younger than us! In the rest of the area we used a modified lasagna method. We used newspapers (6-8 pages dampened) and put down over it a small layer of dirt, mixed with bagged Humus and Manure, and covered it with a 2 inch layer of mulch, trying hard not to raise the elevation more than a little bit & start a war with our neighbors (all at a slightly higher elevation than us & them wanting to keep it like that). We did the work in the fall and let it go for the season. It looked neat and needed no more mowing, with only a moderate leaf cleanup off the rocks (pushed onto the mulched areas). Over the winter I developed a plan to add shrubs to the area, checking books & catalogs for things that can tolerate both wet and clay. I decided to plant only small bareroot shrubs, 12, 18, 24 inches tall, because I had no faith in anything actually being able to live in this spot. I settled on Variegated Red Twig dogwood which I bought locally as small shrubs & Itea, Clethra, a cutleaf Sambucus, & Buttonbush (Cephalanthus occidentalis) that I bought as whips through a catalog. In addition, I purchased a couple of Emerald Arborvitae shrubs locally for some Evergreen color near the back center of the garden on higher ground. I also bought inexpensive (no cultivar name) starts of things like Ostrich Fern, water Iris, & Cardinal flower from a catalog and added a few plants from the pond section of the local nursery, plus moved a few astilbes (that I didn't like the color of) from another part of the garden. To my surprise most everything took quite well. Since that time (more than 5 years ago) I have tried different shrubs and perennials, pulled out a lot of things that got too big too fast, & had a great deal of fun with my "wet" garden. I have no idea if it would ever have qualified as a bog or a fen - but it was certainly wet enough. I have found that a lot of things will grow in the area and on the edges of the area. It never has to be mowed, there aren't any mower ruts anymore, it doesn't need watering, there isn't even much standing water anymore, and it's quite lovely. BTW, local landscapers, 5 of them, had been brought in to look at the yard during the summer before we did this work - none would give us an estimate (no way to get heavy equipment into the yard) and only wanted to plant River Birches or Bald Cypress trees in the corners. They said nothing else would work. A wee bit big for my small suburban lot & wouldn't my neighbors have loved the tree branches spreading all over their yards! I'm glad we did it ourselves. There are really just so many things that love this area. Here's a few: You can't tell from the picture but behind the Lady's Mantles (themselves 2 ft tall) is a dropoff and a big drain right in front of the yellow zinnias, which are further away than they look in the picture. To the left on the top ridge of the bed is Miscanthus sinensis Strictus and to the left Hibiscus moscheutos Sweet Caroline, both huge tall plants, blocking the view into the "wet" garden, except for this peek. Behind them are various water/damp loving perennials & some small shrubs, with a mixed row of damp & clay tolerant shrubs behind them along the fence. Here's the rest of the Strictus grass and Lysimachia Alexander. The entry path to the "wet" garden is just on the left of Alexander. On the left side of this narrow path is a dwarf Meadowsweet, about the same size as Alexander on its own little island. There is another path to the left of it going the other direction to higher ground. You can also see a bit of the Ostrich fern which is actually about 5 ft back and on the far edge of the drainage ditch. Trollius, an early bloomer likes damp. The dark shrubs in the background are Physocarpus Diablo on the higher back ridge, not quite filled out yet this early in spring. Bowles Golden Sedge looks great against the Diablo foliage. Japanese Primrose (Crimson Strain) sprinkled here and there in the area. Love the color. Virginia Bluebells, one of my favorite spring ephemerals. This runs along the fence side of the bed, before the Swamp Hibiscus is even out of the ground.

I think that Kwoods is pointing out that it seems difficult to convince the OP one way or the other on the depth. This is a huge project to tackle if you don't have any previous experience. I think that njb had a good idea to start with plants in a kiddy pool. If I were going to do this I know I would want to know everything I could before I started. I went through all kinds of angst when I was building my little bog. I can't imagine what it would be like if I were trying to build a complicated pond and marsh that required $700 worth of liner and the removal of 40 tons of soil. I'd probably ask local professional pond builders for opinions. Yikes.

this is what I have growing in NO direct sunlight, very shadded: all of these are growing to full bloom and full size in direct mud: 1. cardinal flower 2. blue flag and yellow flag iris 3. water plantain 4. marsh marigold 5. pickerel plant; pickerel rush; pickerel weed 6. variagated sweetflag 7. water cellery 8. water clover, hardy 9. arrow arrum bog arrum; water calla some unidenfied flower, that may be a form of monkey flower - but white - of the genus: Lowes now, the only thing that is not going crazy growing to MAXIMUM potential, are the 12. arrow heads - they are growing big only where planted in direct or partial sunlight. so, rather then wasting your time with a listing or any further research, know that ALL OR ANY bog or marginal is going to do great in shade - unless we are talking about complete cut off from light - NO yellow - direct sunlight has ever hit those plants above for as much as a minute and they are growing great - they are in a corner of the yard under some pine or ceder type of trees.