The first question one should ask is "Why would one want to build a bog garden in the first place?" A Good question with two good answers. First of all, many orchids in the United States live in damp/wet environments such as acid bogs, calcareous fens, and damp meadows. If you want to raise these species you have to provide this semi-aquatic requirement. One of my first failures as an orchid grower was my attempt to raise the snakemouth orchid, Pogonia ophioglossoides. My first two attempts resulted in complete failure because I couldn't believe that this orchid really needed (= required) moist conditions. On the third attempt, a few individuals planted in my newly constructed bog produced around 500 adult flowering plants in about 2 years. In a bog environment, this species acts as an invasive species. In one season this orchid grew via rhizomes 8 feet horizontally from one end of the bog to the other.
A perusal of the literature reveals that many orchid species are found in a diversity of natural habitats. We often think of orchids as being either "acid-loving" or "basic-loving" meaning that they can only survive in acidic or basic conditions. I am not sure if this concept is always valid. I think that at least in some cases the pH of the environment is not as important as moisture content. As an example, Calopogon tuberosus and Pogonia ophioglossoides are two orchid species that are found in acidic bogs in Michigan but in Missouri are restricted to alkaline calcareous fens. In this case, it seems to me that what is important to these two orchids is the presence of adequate soil moisture not the pH of it.
From the literature I have compiled a list of orchid species in the United States that are found in moist environments disregarding the factor of pH. If pH is not, but soil moisture is, an important factor for a given species it should do well in the acid bog whose construction I have described below. In the list of species, I have starred those orchid species which by my own experience have done well in the acid bog described below. Here are the potential orchid candidates: snakemouth orchid, Pogonia ophioglossoides*; dragon's mouth orchid, Arethusa bulbosa; common grass-pink, Calopogon tuberosus*; bearded grass-pink, Calopogon barbatus; many-flowered grass-pink, Calopogon multiflorus; pale grass-pink, Calopogon pallidus*; upland spreading pogonia, Cleistes bifaria; spreading pogonia, Cleistes divaricata; rams-head ladyslipper, Cypripedium arietinum:small white ladyslipper, Cypripedium candidum; kentucky ladyslipper, Cypripedium kentuckiense; small yellow ladyslipper, Cypripedium parviflorum; showy ladyslipper, Cypripedium reginae; California ladyslipper, Cypripedium californicum; little club-spur orchis, Gymnadeniopsis clavellata*; yellow fringeless orchis, Gymnadeniopsis integra; snowy orchis, Gymnadeniopsis nivea; Loesel's twayblade, Liparis loeselii; northern white fringed orchid, Platanthera blepharioglottis; Chapman's fringed orchid, Platanthera chapmanii; yellow fringed orchid, Platanthera ciliaris*; southern white fringed orchid, Platanthera conspicua; orange crested orchid, Platanthera cristata; southern tubercled orchid, Platanthea flava*; large purple fringed orchid, Platanthera grandiflora; green fringed orchid, Platanthera lacera; purple fringeless orchid, Platanthera peramoena; small purple fringed orchid, Platanthera psycodes; shining ladies'-tresses, Spiranthes lucida; and great plains ladies'-tresses, Spiranthes magnicamporum. In addition to U.S. orchids there are bog orchids available from Japan (Pogonia japonicum*, Eleorchis japonicum*, Epipactis thunbergii*) and Europe (Dactylorhiza incarnata, Dactylorhiza purpurella*, Anacamptis palustris var. rosea).

Shown below is a photograph of Pogonia ophioglossoides growing in one of my bogs. Do they look like they are "just hanging on?"

I have found that bog orchids grow very well in my bogs in hot and humid St. Louis in contrast to many non-bog orchids which apparently can't tolerate the heat. I believe that the bog environment provides a cool root environment which is important for at least some orchids. While the surface of the bog can be dry and hot to the touch if you dig down 2-3 inches the environment is moist and quite cool. I also believe that the artificial bog environment because of its loose consistency provides adequate oxygen for the roots. Root and rhizome growth is very substantial. I admit that this evidence is anecdotal but one can't argue with success.
The bog which is being constructed below is an artificial acid bog. The medium of this bog is dead long-fiber peat, Sphagnum papillosum. The advantage of this medium is that it does not decay quickly, holds a large quantity of water, and holds an adequate supply of oxygen. One could use as a medium a heavily organic soil. The problem with this type of medium is that it rapidly becomes anaerobic because of anaerobic bacteria feeding on the organic content. This would result in the death of the plants.


Siteing the Bog

Siteing the bog is an important first consideration which to some extent depends upon your climate. In general, you should site your bog in a sunny location since the majority of bog species are adadpted evolutionarily to full sun because most tree species which could provide shade can't tolerate the high soil moisture. It is easier to provide shade via a shadecloth in a sunny location than to provide a sunny environment in a shady location (by cutting down trees). The site should be as level as possible (or made so) so that the water level in the bog is more or less constant throughout.

How Large a Bog?

For ease of construction and cost I would recommend an 8' X 8' bog. If you need to work in the bog to weed or move plants around, 4 feet is about as far a distance as you can stretch your arms. (By the way, weeding is important because there are lots of seeds that like the nice seed bed that the bog provides.) I have built bogs either of 4" x 4" x 8' treated timbers stacked three timbers high or single 2" x 12" treated boards. I prefer the 2" x 12" treated boards for ease of construction. By the way I have observed no negative effects from the "treated" nature of the lumber. Below is shown a diagram and photo of a bog using the 4" x 4" treated timbers.

Constructing the Bog

1. Nail the boards together to form a square. Apply a 1" layer of sand over the site to serve as a base. Place the square box over the sand and using a level make sure that the square box is level on all four sides.
2. Place a plastic or EPDM liner inside the square box to hold the bog water. An EPDM liner is composed of rubber and is longer lasting than a plastic liner. The sand base previously applied protects the liner from punctures.
3. Nail a 2" X 6" board from one side of the bog to the other about 12" from one edge of the bog. This board goes inside the EPDM liner and serves to separate the future "water reservoir" from the bog proper. See diagram and photo above. In the photo you can't see this board because it is covered with a flat laying 2" X 6" board for decorative purposes. The whole upper surface of the bog structure is also covered with these 2" X 6" cedar trim boards.
4. Purchase a 8' X 8' piece of geotextile fabric from a "pond" store, landscaping company, or concrete store. This fabric is often used before they pave a highway with asphalt or concrete. It is about 1/8" thick and is tough as nails-- you can't tear it, only cut it with scissors. Lay this fabric on top of the EPDM liner inside the bog and attach with roofing nails to the inside edge of the horizontal board that you just previously attached. This fabric is water permeable and serves to separate the contents of the bog (sand and dead long-fibered sphagnum) from the water in the water reservoir.
5. Fill the pond with about 3" of water with a hose. The weight of the water will allow the EPDM liner to conform to the inside shape of the bog. Since water always levels itself, the water in the bog is now perfectly level.
6. Purchase about 5-6 bags of silica sand from a landscaping store,a material supply store, or a sandblasting supply store. Caution here--- Silica sand is hazardous to your health as it is easily dispersed through the air and into your lungs. Wear a respirator!!! Silica sand is used because it is basically inert and won't alter the pH of your water in the bog. You can use other types of sand but calcareous based sand will increase the pH of your water. Pour the bags of silica sand carefully into the water inside the bog. Using a rake with the sharp tines UP to avoid puncturing the EPDM membrane spread out the silica sand until there is a even thin layer of water over the sand. Voila, you now know that your bog is absolutely level (because water always levels itself). One advantage of filling the bog with water at this stage is that it keeps the silica sand dust to a minimum once it is under water. Don't place any silica sand in the water reservoir. Of course, by this point the water level in the water reservoir is at the same level as the water in bog.
7. Continue to add water to the bog until there is about 1 inch of water over the silica sand. With a nail mark the water level in the water reservoir. This water level is the water level that you want to maintain indefinitely in the bog.
8. Purchase approximately 5 bales of dead dried long-fibered sphagnum (Sphagnum papillosum) from Mosser Lee Company in Michigan or Hummert's International in St. Louis, or at any other reputable dealer. This, by the way, is not peat moss. Warning-- wear a respirator again when playing with the dried sphagnum. Break the sphagnum apart and fill the bog with about 5-6 inches of the moss. Fill the bog with water to help the sphagnum absorb the water. It usually takes overnight for the sphagnum to absorb the water completely. I usually compact the sphagnum a little bit by hand at this point.
9. From a "pond" store purchase a water-leveling float device (basically a toiltet float). They are usually around $40. Drill a hole in the end of the water reservoir (not shown in the bog diagram) and install the float device. Use silicone to seal the float device. These float devices are adjustable by adjusting the angle of the float. The goal here is to adjust the water level in the water reservoir to maintain the water level at about 1 inch above the surface of the silica sand (You marked this water level in step 7.) With this water level, water will move vertically by capillary action up through about 4-5 inches of the long-fibered spaghnum.
10. Water, Water everywhere but not a drop to drink. You need to supply your bog with good water. By good water, I mean soft water with very low mineral content. In municipalities with "good" water, water from a hose can be used to supply the bog through the float control device. In places where the water is "bad" (high mineral content, high pH-- St. Louis water is an example of "bad" water with a TDS of 300mg/l and a pH of 10.5). If you live in places with "bad" water you can either use a Reverse Osmosis (RO) system to supply your water or you can collect rain water off your roof into a cistern. In St. Louis I had a RO system in my basement which supplied my bogs. On a hot summer day in August, my three bogs combined could evaporate 50 gallons of water.
11. Drill a couple of holes through the walls of your bog about 1.5 inches above your designated optimum water level. These are overflow holes which will serve to lower the water level in your bog when you have those 5" rainfall events. You don't want to suffocate your plants with too much water. You will find that your plants will respond to your designated optimum water level by growing their roots to a certain depth relative to your optimum water level. This depth will vary from species to species. Don't screw around with adjusting your optimum water level if you don't need to.
12. Plant your plants about 2-3 inches deep. During the hottest part of the summer poke your finger down into the spaghnum to determine moisture level. If you judge that the moisture is not close enough to the surface you could change you optimum water level by adjusting your float valve.
13. As a finishing touch you could add living sphagnum to your bog. Over the course of a summer the living sphagnum will cover your bog and will provide additional evaportive cooling to your bog. Each Spring your orchids will come up through the living sphagnum. By the way, your living sphagnum will freeze solid if you live in St. Louis or in a comparable climate. Don't worry, it thaws out and does just fine-- ie doesn't die. You can purchase living sphagnum moss on E-Bay (type in "Sphagnum") or else from the Meadowview Biological Research Station. They have some very attractive strains of Sphagnum.

My Spouse Hates My Bog

If your spouse hates your bog tell him/her to wait and see how beautiful the orchids will be once they have become established. In the meantime you could build a more decorative type of bog. I built a bog out of stacked flagstone rocks. Put a regular liner inside and installed a water reservoir at one end (not visible from above). Below is what this rock bog looks like. Notice the rose pogonia orchids, pitcher plants, and sphagnum moss covering the bog. This bog is situated next to an artificial streams which runs through our back yard.
(Notice the two types of bogs in the photo below. Both of them are raised beds. The purpose of the raised bed is so that deer won't have to bend over so far when feeding on your orchids!! This is important for orchid lovers in Michigan and Ocean Shores, WA, which have healthy deer populations. In the wooden bog notice that the bog is completely enclosed in a plastic fabric for deer protection.)

My Bog and My Climate

Where you live determines your climate. Presently, I have two homes one in St. Louis, Missouri, and the other in Ocean Shores on the Washington coast. I have bogs in both places. I have discovered that the differences in the climate between the two places is quite different with St. Louis August temperatures occasionally exceedling 100 F. Ocean Shores, on the other hand, during August rarely gets over 65 F. Temperature does affect plant growth and consequently flowering time. In order to get some orchids to flower in time to get good seed set I have modified the bogs by adding four sides and a roof of fiberglass paneling. This has increased the typical daily temperature to about 80 F. This has speeded up flowering. People living in cool or cold climates may need to modify their bogs to accommodate certain species of orchids. I will attach a photo soon of this new modified bog.