ALL bonsai should be in fast draining gritty soil, it's the proportion of organics (bark, coarse loam, etc.) that changes, and it's very hard to say which trees will do best with what percentage (beyond very basic info) because you don't know where they live, in or out, heating, what sun they get, etc. It's more important to learn each tree's needs in it's particular environment by observation than to try and use a quick fix.

man its hard to see the slope sideways... or is it just me ... the pic is sideways for me ... i presume the rocks are on the high side??? and why do you presume it will stay damp.. if it is ON THE SLOPE ... or do you mean its at the bottom of the slope ... you havent lived there a whole year yet have you???? why do you think it will stay wet ... more facts please ... i am just wondering if you are making some faulty conclusions ... ken

Around the fringe of a swamp: (this is for my area but you can look up which will work for you) Coast Redwoods Sequoias Western Red Cedars of many varieties (but they don't like standing water for long) Shore Pine (Pinus contorta var contorta) Leylands Blue Atlas Cedars Gingkos Red Horsechestnuts Purple Robed Locust (Robinia 'Purple Robe') Giant Dogwood (Cornus controversa) Quaking Aspen Catalpa Sugar Maple Raywood Ash Green Ash Nellie R Stevens Hollies Himalayan White Birch Japanese Maples Quercus virginiana Quercus myrsinifolia In the swamp: (6-11" pooling water in winter) WILLOWS -- Prairie Cascade Willow -- awesome, truly amazing tree Babylonica Weeping Willow Curly Willows Blue Arctic Willows Rosemary Willows Nishiki Dappled Willows Red Barked Willow (Salix alba 'Chermesina') Violet Willow (Salix daphnoides) Lapland Willow (Salix lapponum) Bay Laurel Willow (Salix pentandra) Swamp Tupelo (Nyssa aquatica) American Sycamore Buttonwood (Platanus acerifolia 'Bloodgood') London Plane Tree (Platanus occidentalis) Sweetgum Black Cottonwood Bald Cypress Blueberries 2 kinds of swamp Eucalyptus Swamp White Oak Swamp Red Maple Swamp Magnolia River Birch Alder

Arctostaphylos 'Austin Griffiths' Ceanothus 'Ray Hartmann' Cocculus laurifolius Lagerstroemia hybrids Psidium cattleianum Rhapiolepis 'Majestic Beauty' Tecoma (Stenolobium) stans Viburnum suspensum Joe