What is a bog garden?
- An area or pocket of saturated soil that is never allowed to dry out.
- Contains moisture-loving plants that grow in conditions of "wet feet and dry ankles."
- "Wet feet" but no standing water.
- Types of bogs:
A. Wild bogs:
- Bogs or wetlands are low lying areas in the natural terrain where flora and fauna thrive in a moist environment.
- Natural bogs often form in glacial lakebeds and shallow depressions over hundreds of years.
- May be shallow sub-surface rock layer, which holds in the water.
- Habitat where slow movement of water creates conditions for slow decomposition of dead plant matter.
- Soil may be high in organic matter and quite acidic: sphagnum/peat moss may be present.
- In some habitats, carnivorous/insect catcher plants such as Sundews, Pitcher plants, or Venus’ Flytraps may be found.
B. Ornamental bog gardens:
- Extension of the water garden; bog garden linked to a pond; overflow bog garden:
- Created within the perimeter of the water garden by using a permeable retaining wall to confine the soil and separate it from the open water of the pond.
- Extension of pond liner and creation of barrier lets water permeate the soil but prevents soil from falling into the pond.
- The independent bog; oasis garden; damp garden; irrigated bog garden:
- Created by underlaying the bog garden with a non-permeable membrane that slows down the movement of water through the soil.
- Made with liner independent from pond allowing greater flexibility in siting and shape.
- As liner is completely covered with soil and not exposed to deterioration from ultraviolet light, cheaper materials like polyethylene can be used.
- No water level to be maintained as in a water garden, so construction need not be watertight; perforation of liner fabric recommended to prevent stagnation and anaerobic soil.
II. Advantages of a bog garden:
- After falling in love with aquatic plants, it is natural to explore other ways of incorporating these lush, beautiful, and interesting plants into the surrounding garden.
- Low maintenance once established. No fish to bother the plants.
- Don’t have to worry if bog plants are getting too much or too little water.
- Because a damp/bog garden does not have standing water within it, there is no algae proliferation from excess nutrients.
- Should be low-lying and where surface drainage will naturally collect.
- Sun, or half day sun, or filtered shade.
IV. How to build:
A. Extension of water garden:
- Bog garden linked to pond should be no more than 10 to 15% of the total surface area of pond.
- Bog soil must be independently and regularly supplied with water to prevent plants from "wicking" out the water from the pond,
- To extend pond area for bog without creating problem of water loss from pond, either:
- extend large-enough sheet of liner from pond to take liner up above ground level and back under again to line a bowl-shaped bog garden
- or, line a hole dug by the pond’s edge with separate liner.
- outer edge of hole should be higher than water level of pond.
- Disguise humps of liner above ground level that form a barrier between pond and bog area by mortaring on flat-bottomed rocks. To avoid unnatural look the tops of the rocks should not be a lot higher then that of the soil level of the bog.
- Follow remaining directions below.
B. Independent bog/oasis garden/damp garden:
- Dig hole at least 18" to 24" deep. Deeper soil is more accommodating to the root systems of mature plants.
- Can have walls sloping outward slightly to keep sides from caving in.
- Cushion bottom of hole with sand or polyester matting.
- Lay waterproof material—butyl, heavy gauge polyethylene, PVC, EPDM --could be scraps of liners from other pond projects—into excavation.
- If it is a solid piece of liner instead of scraps, punch a few small holes in the material and cover holes with gravel. Because of our hot climate, punch holes in sides a few inches from bottom instead of holes in bottom to preserve more moisture.
- If bog is large, rim the edge with edging material to contain bog’s moisture and to prevent deterioration of the bog’s perimeter.
- Make provision for water to enter the bog. Examples:
Cover bottom of excavation with 4" layer of gravel.
Use a heavy, clay soil or amend soil with some organic matter and clay soil and return to excavation. Tamp soil as you go.
Some recipes for bog soil combine peat moss, compost or small amount cow manure, and heavy black dirt. Others say compost and heavy soil. We got the heaviest soil we could find at Bob's Material Supply and did not add amendments.
Plant plants in dry soil.
Gently but thoroughly water in plants with sprinkler or hose.
If there is subsidence of the soil after a few days, add more soil.
Pull weeds; add mulch.
- Run rigid pipe through a watertight valve in the liner to water source. Pipe inside liner is perforated to allow water seepage. Cover pipe with gravel to prevent soil from clogging holes.
- Could be constructed under a gutter downspout or run a solid pipe from the gutter to the edge of the bog, then switch to slotted pipe buried within the bog. Cover pipe with gravel to prevent soil from clogging holes.
- Lay perforated/laser cut drip irrigation poly-tubing on surface or bury in soil, covered with gravel to prevent clogging. Attach to irrigation system or pond pump line.
- Bury a soaker hose within the bog. Hide open end among perimeter plants and hook to a garden hose as needed.
- Install overflow pipe to draw water from pond.
V. Partial plant list:
Note: Many marginal aquatic plants not designated as bog varieties will flourish in bog conditions.
Common name____________Botanical name
Arrowhead ______________ Sagittaria
Bat-faced Flower _________ Cuphea llava
Canna _________________ Canna
Cardinal Flower ___________ Lobelia cardinalis
Cattail, dwarf ____________ Typha minima
Corkscrew rush ___________ Juncus spiralis effusus
Hair grass _______________ Eleocharis acicularis
Horsetail ________________ Equisetum hymenale
Iris/Yellow Flag ____________ Iris pseudacorus; and other water/bog iris
Marsh Marigold ____________ Caltha palustris
Monkey flower ____________ Mimulus cardinalis
Papyrus/Nile grass _________ Cyperus papyrus
Miniature Papyrus __________ Cyperus haspan
Pickerel Weed _____________ Pontederia cordata
Common Sweet Flag _________ Acorus calamus
Variegated Sweet Flag _______ Acorus gramineus ‘Variegatus’
Taro ____________________ Colocasia
Umbrella Palm/grass, dwarf ___ Cyperus alternifolius
Water Thalia/Water Canna ____ Thalia dealbata
Water Nasturtium/Watercress __ Nasturtium officinale
VI. Selected resources
On the Web, enter "bog garden" or "bog gardens" in your favorite search engines.
American Horticultural Society Complete Guide to Water Gardening. Peter Robinson, 1997.
"The Bog Garden." Anita Nolan Nelson. Watergardening Magazine, April 1996, pp.31-35.
"The Bog Garden Revisited." Anita Nolan Nelson. Watergardening Magazine, March/April 1999, pp. 26-32.
Complete Book of the Water Garden. Philip Swindell & David Mason, 1990.
Garden Pool Design. Helmut Jantra, 1995.
Ponds & Water Features. Peter Robinson, 1999.
Sunset Water Gardens, 1997.
The Water Garden. Peter Robinson, 1995.
The Water Garden Month-By-Month. Andi Clevely, 1997.
Water Gardening: Water Lilies and Lotuses. Perry Slocum & Peter Robinson, 1996