Garden site

We are always looking for new ways to showcase aquatics in the landscape. Here at Hughes Water Gardens we like to have displays that help our customers visualize what something will look like in their own yards. Over the years we have been  using water bowls, waterfalls and ponds to illustrate how most of our aquatics can be blended into traditional gardens, but for two growing seasons now Niki Atterbury, our retail manager, and I have been mulling over how we could design something new for garden enhancement, hence the idea for our moist soil garden was born.
This project is so simple it seems too easy. It's one of those "Why didn't I do this before?" kind of thing. But beware the process does require some willingness to wield a shovel. How big an area you want to create dictates how much wielding you may actually have to do. In our case, thankfully, the wonders of modern man expedited the process. We did go a bit overboard as far as the depth needed for a flourishing environment, but when you have access to a toy like a backhoe that was probably to be expected.
I've had great luck with using a depth of 6-12 inches (15-30 centimeters) as long as the soil is the type that retains moisture or can be saturated easily on a regular basis. Our depth here approached 20-24 inches (51-61 centimeters), so we back-filled the hole a bit to get our depth closer to 15-18 inches (38-46 centimeters).
We found an older used piece of 45 mil EPDM pond liner and poked holes in it to allow the water to seep out over a long period of time. This was done by using an old pair of scissors, closed; the holes were spaced about 24 inches (30 centimeters) apart in rows also spaced 24 inches (30 centimeters) apart.

Excavation by Filiberto

Liner in place

The formula for getting the liner piece just the right size is:
Width = maximum width of the hole + (2x maximum depth) + 2 feet (0.6 meters)
Length = maximum length + (2x maximum depth) + 2 feet (0.6 meters)
The extra two (0.6 meters) feet in the equation is to make sure you have a good edge width along the full perimeter. The space for our moist soil garden is 16 feet long (4.9 meters) by 10 feet (3 meters) wide.

Backfill soil

The soil we used to fill our lined hole was the somewhat clay type that is very prevalent here. We added 10% sandy loam and about 10% compost. The sandy loam adds a bit of needed viscosity, while the compost helps nutritionally and in keeping the area wetter longer. Using the same compost to top-dress the area further increases our time between watering.
A soaker hose watering system for easy and even distribution is the most convenient method I have found, and adding some sort of timer can further reduce the need to worry about getting enough water to your moist soil garden. Once you learn how long it takes to fully saturate the bed, the process becomes routine.
Let's review. You simply dig the hole, lay down the liner; puncture it, refill the hole with your mixed soil, set a soaker hose on top, spread compost over your area and then you can carefully plant through the compost. Sounds easy, right? I know you're saying, "Not so much", especially when you did all that shovel wielding and I had the backhoe. Luckily it gets better, because the planting is always  the fun part, yet this time I'm the only machine at work 
Our planting plan starts with hardy plants and then we mix in more tender tropical varieties as the warm weather comes on. By doing a two-stage planting process we have an exciting mix of plants that will give us both year round interest and extra beauty through the summer season.

Soaker hose

Compost top-dressing

First phase

Our site is a little bit light deprived (aren't we all, especially here in the Northwest?) so this will be a learning experience for us. Over time we will get to see how various varieties survive under these conditions. I foresee a minimum of at least six hours of sunlight, hopefully more like eight. I like the idea of starting out with the hardier plants first because we are creating the long term bones of the garden that will set the stage for many years to come.
As in most garden designs it is important to keep the shorter plants in the foreground and the taller plants in the back. Our location will be viewed from the front and from an upper pathway looking down from the rear. The tallest plants in our garden are more at the center and also sprinkled along the sides.
One crucial point needs to be addressed: avoid so-called invasive plants that become burdensome if left to their own devices it may end up spoiling all of your hard work. Below I have  provided general plant information on who to invite to the party and who to leave off the list. If you inadvertently plant something that appears to be taking over in just one growing season, remove it. Aquatics that grow with a clumping habit are more suited for this confined type of space. 
This project will continually provide additional knowledge for us over time while increasing customer awareness of the vast array of aquatics that can be grown out of the pond -- a win-win situation. Hopefully this will also help you broaden your plant palette with new choices for your moist soil garden.

Front view with all plants

Upper path view

Phase One Plantings 

 Acorus calamus 'Variegata'

 Variegated Sweetflag

 Acorus gramineus 'Ogon'

 Ogon Sweetflag

 Astilbe sp.

 Bletilla striata

 Chinese Ground Orchid

 Caltha palustris 'Alba'

 White Marsh Marigold

 Carex elata 'Bowles Golden'

 Bowles Golden Sedge

 Darmera peltiphyllum

 Umbrella Plant

 Filipendula ulmaria

 Bog Meadowsweet

 Juncus effusus 'Nana'

 Dwarf Corkscrew Rush

 Lobelia cardinalis

 Red Cardinal Flower

 Lobelia fulgens 'Queen Victoria'

 Queen Victoria Cardinal Flower

 Lysichiton americanum

 Skunk Cabbage

 Ophiopogon planiscapes 'Nigricans'

 Black Mondo Grass

 Peltandra virginica

 Spoonflower

 Primula japonica

 Japanese Primrose

 Rogersia podophylla 'Rotlaub'

 Rogersia tabularis

 Saururus chinensis 'Flaming Dragon'

 Flaming Dragon Lizard's Tail

 Thalia dealbata

 Powdery Thalia

 Zephyranthes candida

 Rain Lily

 Phase Two Plantings

 Bacopa caroliniana

 Lemon Bacopa

 Canna assorted

 Colocasia esculenta 'Black Magic'

 Black Magic Taro

 Colocasia esculenta 'Illustris'

 Imperial Taro

 Cyperus alternifolius

 Umbrella Palm

 Cyperus papyrus 'King Tut'

 King Tut Egyptian Papyrus

 Rotala indica

 Pink Sprite

 Ruellia britonniana 'Chi Chi'

 Pink Bellflower

 Other Plant Recommendations

 Acorus assorted

 Hibiscus moscheutos

 Swamp Hibiscus

 Hibiscus coccineus

 Great Red Hibiscus

 Hosta assorted

 Iris ensata

 Japanese Iris

 Iris laevigata

 Pond Iris

 Tulbaghia violacea 'Variegata'

 Variegated Society Garlic

 Plants Not Recommended

 Arundo donax (both varieties)

 Giant Reeds

 Carex (most varieties)

 Sedges

 Equisetum

 Horsetails

 Houttuynia

 Houttuynia Chameleon and Green

 Hydrocotyle

 Pennyworts

 Myosotis

 Water Forget Me Nots

 Oenanthe

 Water Celery

 Phragmites

 Common Reeds Golden and Variegated

 Spartinas

 Spartina

 Typhas

 Cattails

 By July the moist soil garden is growing in.