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Making a Bog Garden

A patch of bog will make an interesting addition to any garden or school grounds. By creating waterlogged conditions, you can artificially create a bog garden.

Peat bogs develop where the ground is waterlogged and is, as a result, poor in oxygen. As the plants growing under these conditions die they cannot be decomposed because the micro-organisms that carry out this vital work need oxygen, therefore the plant remains accumulate as peat. The main source of water and minerals to plants in the bog is rainwater. This means that bogs are poor in minerals and, as a result, tend to be acidic.

A bog is relatively inexpensive and easy to construct. Once established it will not require too much maintenance. It will add a new dimension to your garden in a number of ways by:

• Making some unusual habitat types available for school study.
• Offering refuge to some uncommon plant and animal communities.
• Creating horticultural and decorative possibilities for investigation.
• Involving local school children (and if possible their families) in an environmental improvement scheme.

The procedure for creating a bog garden is similar to that for making a pond. It needs to be planned carefully.

Planning & Location

Plan to construct miniature examples of various bog communities including an area of wet bog, a bog pool and a peat hummock for drier bog species. You can also include a marshy area where plants grow in shallower peat with some drainage.

Before you do any actual digging, you need to consider a few points:

• Locate the bog in or around the lowest point in the garden.
• A sunny location, preferably south facing, is most conducive to attracting the greatest variety of wildlife.
• Locate the bog away from trees or over-hanging shrubbery that cast shade, block rainfall and create a lot of leaf litter in winter.
• Do not locate the bog too near to a house as constant movement of people may disturb it's wildlife.
• You may need to have the area fenced off if the bog contains a pool as it may be a danger to children.
• Most importantly you will need a good clean supply of rain water to water the bog during dry summers.

Construction

The best time of year to begin construction is from September to March. The hole you dig must be lined to create waterlogged conditions. There are 4 lining options:

PVC sheeting - Quite durable and can be repaired using bostik and rubber patches.

Nylon-reinforced PVC - Brand names - Flexilene and Wavelock. A strong, durable lining.

Butyl Rubber - Stronger than PVC lining but not puncture-proof. It is both flexible and durable.

Polythene Sheeting - Comes in 500 or 1,000 gauge. Inexpensive and, when used as a double layer, quite strong.

Dimensions

Once you have decided on the bog's location in a garden, the next step is to mark out it's shape by using pegs and string. This can be done any number of times until you are happy with the overall outline. Before digging commences, the following points should be noted:

• The total area should cover at least 4 meters squared (i.e 2m x 2m).
• The bog depression should be at least 2 feet deep. If you are including a marsh area this need only be 1 foot in depth.

Digging

• Dig a hole the size and shape that you want the bog to be. Keep the turves to one side.
• Dig a small trench around the perimeter to bury the liner.
• Remove any sharp stones etc. from the excavated site.
• Allow at least an extra 10cm for cushioning below the liner when you dig the hole.

Lining

A fairly accurate way of calculating the amount of liner required:

Maximum Length of Bog Hole + Maximum Depth X 2 = Liner Length

Maximum Width of Bog Hole + Maximum Depth X 2 = Liner Width

• Make sure that the ground is free of any sharp objects
• Line the bog hole with old carpet, or a thick layer of newspapers or a 5cm thick layer of sand or sieved soil.
• Spread the liner over the hollow and bring up to cover the trench.
• The lining in your shallower peat area for marsh plants needs to be perforated so that some drainage can occur.

Filling

• Fill the lined depression with wet moss peat (peat which has not been extracted from sites with conservation value). Do not use peat that has been taken from a cutaway bog as this will be full of weed seeds. Do not use peat compost as this usually has chemical fertilisers added which will be too rich for most bog plants and may kill them.
• The moss peat should then be saturated with water.
• Trim and bury the edges of the liner, possibly with the turves you have already set aside. Exposure to sunlight will damage the liner.

Bog pools - Dig a depression in the peat 12 inches deep to make a bog pool. Keep the peat aside.

Hummock - Build the peat, from the bog pool, into a hummock for drier bog species.

Marsh - Fill the area for the marsh with a soil and compost mixture to create more nutrient rich conditions for marsh plants.

Access and Safety

Stepping stones or a wooden platform at the edge will allow you to stand and observe the bog. Consider a low fence or barrier if you have a pool and are concerned about children's safety around the bog - a low fence may also be a good way to prevent the bog being trampled.

Watering System

The most important thing to remember is that a bog has to be kept wet with the water level topped up to the surface of the peat for best results during the summer months. A system needs to be established to ensure a continual supply of water to the bog. Rain water is best but you can use tap or well water in an emergency. Examples of watering systems:

• Water pumped from a nearby well into the bog pool with an overflow running into the marsh area.
• Pipe water from a rain water collection point, into the bog pool area. The quality of the water is crucial. It needs to be free from nutrients to retain the acid loving plants in the bog. During a hot dry summer the water level can be topped up with tap water if necessary. (Do not spray bog with a garden hose as this will wash the peat away.) And remember - never fertilise the bog - this will kill it.

Planting

The best time for planting is in the autumn or spring. There are a number of options for introducing plants and moss species on to the bog.

• You can visit a local nursery or garden centre who can supply a variety of bog species or can order them if they do not already have them in stock.
• Visit a bog and collect seeds from the various plants growing there in particular bog cotton, ling heather, deer sedge and cross leaved heath. Collect seeds at a few different times throughout the year or from a few sites to get the full range of species.

Cut sods (12" x 12") of bog vegetation from the surface of a dying bog. These should be taken from a peatland site that has already been destroyed. The sods will act as focal points for the colonisation of the peat with bog mosses and plants. You must ensure that sods are not taken from a conservation worthy site.

Maintenance

The best time of year to tidy up the bog is during the dormant period in winter. Every two years, plants will need to be pruned. Ling Heather should be pruned in autumn after flowering, otherwise it gets too tall and dominant. Every 3 years the pools need to be opened by removing excess Sphagnum and other plants. Spring is the best time to take out any plants and divide them.

You must remember that you are never going to create a true bog, your garden bog is artificially created so it is more like a regenerated site and must be treated as a contrived habitat. Some plants will suffer from the fluctuating conditions and exposure while others will do better. You will have to help balance this situation. Pollution may also be a problem in urban areas. If there is excessive nutrient build up, it may necessitate more regular pruning and weeding.

Do's and Don'ts

• Don't let your bog dry out.
• Don't walk or trample on the bog.
• Don't fertilise the bog or use chemical sprays on it.
• Do keep a bog pool clear of litter and debris in the autumn.
• Don't disturb wild bogs to make a bog garden.

Remember, water is life in the bog - So keep it wet !

Plants for wet bog:

• Cross leaved heath - Erica tetralix
• Many-headed bog cotton - Eriophorum augustifolium
• Cranberry - Vaccinium oxycoccus
• Bog Asphodel - Narthecium ossifragum
• Bog Myrtle - Myrica gale
• Lichens - Cladonia species
• Sundew - Drosera rotundifolia
• Bog Rosemary - Andromeda polifolia
• White beak sedge - Rhynchospora alba
• Bog mosses - Sphagnum species

Plants for the bog pool:

• Many-headed bog cotton - Eriophorum augustifolium
• Quaking Sedge - Carex limosa
• Bottle Sedge - Carex rostrata
• Buttercup - Ranunculus flammula
• Bogbean - Menyanthes trifoliata
• Marsh Cinquefoil - Potentilla palustris
• Bladderworts - Utricularia species
• Starworts - Callitriche species
• Pool Bog Moss - Sphagnum cuspidatum
• Pondweed - Potamogeton polygonifolius

Plants for drier hummock:

• Cross leaved heath - Erica tetralix
• Deer Sedge - Scirpus caespitosus
• Heather - Calluna vulgaris
• Bell Heather - Erica cinerea
• Single Headed Bog Cotton - Eriophorum vaginatum
• Cranberry - Vaccinium oxycoccus
• Heath Rush - Juncus squarrosus
• Heath Bedstraw - Galium saxatile
• Heath Milkwort - Polygala serpyllifolia
• Feather Moss - Hypnum species
• Cup Lichens - Cladonia species
• Bilberry - Vaccinium myrtillus
• Crowberry - Empetrun nigrum

Plants for the marsh:

• Water Horsetail - Equisetum fluviatile
• Jointed Rush - Juncus articulatus
• Marsh Marigold - Caltha palustris
• Crowfoots - Ranunculus species
• Bugle - Ajuga reptans
• Lady's Smock - Cardamine pratensis
• Buttercup - Ranunculus lingua
• Meadowsweet - Filipendula ulmaria
• Ragged Robin - Lychnis flos-cuculi
• Flag Iris - Iris pseudocorus
• Water Mint - Mentha aquatica