Orchidists have Holman (1976) to thank for designing and testing the bog garden method for growing hardy orchids. I have used some vari-ation of the basic design to create growing places for every species of hardy orchid in my collection, with the exception of Bletilla and the species that love strongly acid soil. Orchid growers familiar with Phrag-mipedium, a genus of tropical slipper orchids, will quickly get the point.
Like this cousin, many cypripediums, to choose but one example, flour-ish in a growing medium constantly replenflour-ished with moisture from below. Growers display spectacular specimens of Phragmipedium bes-seae that have been grown in pots set in a dish of water. The reservoir ensures that the growing medium will never dry out completely, and the composition of the medium ensures that it will remain loose, fluffy, and well oxygenated. The Holman bog garden simply accomplishes the same thing on a much larger scale.
In its simplest and most easily constructed form, the bog garden con-sists of a rectangular frame made of 2-by-12-foot pressure-treated
lum-General Principles of Hardy Orchid Cultivation
The completed bed with Cypripedium acaule plants in place.
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ber (or another material impervious to rot). Three 8-foot pieces will make a 4-by-8-foot bed with only one cut. Square up the pieces and se-cure them with 3-inch exterior wood screws. Set the box in position in the garden.
It is extremely helpful to have a level site covered with landscape fabric cut a few inches larger than the bed. You may need to bring in soil, sand, or gravel to level the site, or to do a bit of excavation by hand. For a 4-by-8-foot bed, this should not be too onerous, however.
Once the bed enclosure is in place, use a carpenter’s level to make sure it sits level in both directions. Having the bed level ensures even distri-bution of moisture throughout the growing medium it will eventually contain.
When you are satisfied with the placement of the bed, cut a piece of plastic sheeting 6 by 10 feet. Depending upon how long you want the
The first step in assembling a raised bog garden bed involves assembling a wood frame to contain the growing media.
bed to last, the sheeting can be anything from 6-mil polyethylene film to a 45-mil rubber roofing membrane. The best compromise between cost and durability may prove to be 32-mil polyvinyl chloride, which is sold at DIY stores and garden centers for lining garden ponds. Six-mil poly-ethylene will last only two or three seasons but can be used for a tem-porary bed. Roofing membrane, by contrast, is nearly indestructible.
Regardless of the material chosen, line the bed with the plastic, cen-tering the sheet in the bottom and smoothing it toward the sides. Make neat folds at the corners and staple them in place with a heavy-duty staple gun. You want to end up with the plastic lining extending at least
General Principles of Hardy Orchid Cultivation
Line the frame with plastic, stapling it in place.
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Trim away excess plastic with a razor.
Add a layer of filler material about 6 inches deep.
halfway up the sides of the bed all around. There should be plenty of excess, which can be carefully trimmed away after stapling the lining in place. Don’t worry about doing a perfect job, as the edges will be hid-den by the compost. Do make sure the top edge of the liner is trimmed evenly all around, as, again, this ensures even distribution of moisture within the bed.
Directly above the edge of the liner in several spots drill a 1-inch-di-ameter hole using an electric drill fitted with a spade bit. This provides extra drainage in times of heavy rainfall. Arrange the holes in an at-tractive pattern, if that suits your taste.
Various materials have been suggested for filling the liner to provide a waterlogged reservoir to irrigate the upper half of the bed. Having tried several, I find shredded mulch made from the southern bald
cy-General Principles of Hardy Orchid Cultivation
Spread the filler material evenly in the bottom of the bed.
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press to be the most satisfactory material. It is lightweight, does not rot, and is sold in bags at garden centers. That said, any nondecomposing, relatively inert material will do. If orchids preferring neutral to alkaline conditions are to be planted in the bed, crushed limestone should be the material of choice. Sixteen cubic feet of filler will be required.
After filling the reservoir, flood the liner to overflowing with a garden hose. Water should pour from each of your drainage holes before you shut off the hose. If you are using a filler material that absorbs water, such as the cypress mulch, allow it to sit overnight to become
satu-Flood the filler material with water and allow it to soak over-night before proceeding with construction.
rated. Obviously, if you are using a nonabsorbent material such as gravel, you can skip this step.
Another 16 cubic feet of orchid growing medium will be required to fill the bog bed. You can use any of the following media, depending upon the orchids you plan to grow:
CRIBB & BAILES (1989) Australian terrestrial mix Two parts sharp, gritty sand (could substitute perlite) One part sterilized loam
One part screened pine bark fines
2 teaspoons each blood meal and bone meal per 2 gallons of mix CRIBB & BAILES (1989) bog mix
for Platanthera
Three parts coarse, gritty sand or perlite (must use sand for outdoor beds, as perlite will float to the surface eventually)
Two parts sphagnum peat Chopped pine needles for mulch CRIBB & BAILES (1989) terrestrial mix Two parts sterilized clay loam
Two parts sharp, gritty sand (could substitute perlite) One part screened beech or oak leaf mould
One part screened pine bark fines
1 teaspoon each blood meal and bone meal per 2 gallons of mix DURKEE (2000) Cypripedium acaule mix
Two parts partially composted pine bark fines One part chopped sphagnum moss
PHILLIPS (1985) woodland wildflower mix for Aplectrum and Bletilla
Two parts partially composted pine bark fines Two parts peat moss
One part perlite
19 ounces dolomitic limestone per 4.5 cubic feet of mix
2 tablespoons Osmocote 14-14-14 per 4.5 cubic feet of mix (optional)
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TULLOCK Cypripedium acaule mix
for C. acaule, Disa, and Australian species Two parts partially composted pine bark fines One part peat moss
TULLOCK general purpose mix
for Bletilla, Calopogon, Platanthera, Pleione, Spiranthes, and Tipularia Two parts partially composted pine bark fines
One part long-fiber sphagnum moss One part perlite
TULLOCK general purpose mix with lime
for Galearis, Cypripedium parviflorum, C. pubescens and C. reginae Two parts partially composted pine bark fines
One part long-fiber sphagnum moss One part perlite
1 tablespoon pelletized limestone per 6- to 8-inch pot
Plant the orchids so that their crowns lie just at the surface of the bog bed.
The completed framed bog bed two months after planting.
Mix the components in batches in a wheelbarrow before adding the medium to the bed. Do not risk puncturing the plastic liner by using metal tools in the bed itself. The medium should be light enough to permit planting with a hand spade or even your gloved hands. Flood the bed again until water drains from the holes and you are satisfied that the medium is thoroughly moistened. The bed is now ready to plant.
It is easy to see that the basic bog bed can be elaborated upon in any number of ways to create a more dramatic garden display or to inte-grate with existing landscaping. You can excavate for the reservoir, in-stall drainage pipes for the necessary overflow, and use anything from plastic to concrete for the liner. As long as the basic design provides for 6 inches of growing medium atop a permanently flooded reservoir, the method will work. As with the simpler growing bed, more elaborate in-stallations may require professional assistance.
General Principles of Hardy Orchid Cultivation
Constructing an in-ground bog bed requires digging, and lining the excavation with heavy plastic.
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With filler material in place, this in-ground bog waits to receive growing medium and plants.
The completed bog garden, one year and two months after planting.
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The bog garden after two years and four months of growth.