If you drop by HortPark recently and took notice of the Water Garden located in front of the Visitor Center, you would have seen the floating gardens that have been set afloat on the water surface.
These floating gardens are a practical solution so that aquatic plants can still be displayed as the pond currently has a hard bottom with an undergravel filtration system installed at its base. There is neither an appropriate substrate at base nor containers can be put in to grow and display aquatic plants.
Each floating garden is created using readily available materials (see schematic diagram for details of construction). The floatation device took us a quite some time to source. It comprises a slab of extruded polystyrene board which is usually used for insulation of roofs. Unlike widely available white polystyrene boards used in art and craft, this board is made of dense polystyrene is more buoyant, resistant to wear and tear under the elements and does not absorb significant amount of water.
A selection of aquatic marginal plants, which naturally grow in waterlogged soils along a pond’s edge, with different growth forms, foliage textures and colours, is creatively combined to plant up these gardens that magically hover on the water surface. Of particular note is the use of North American Pitcher Plants (Sarracenia), which are colourful, insectivorous plants that grow in sunny and boggy sites in their native habitat.
Besides being decorative, floating gardens, in general, draw excess nutrients from the water column, especially if you feed your fish frequently. Fish waste that is produced in excess can lead to algae blooms. On a larger scale, such set-ups perform phyto-remediation work, where plants help to purify water in reservoirs, lakes and rivers.
Floating gardens also promote biodiversity. They provide shelter for fish and other aquatic organisms from the sun and predators. Dragonflies and damselflies are given a place to perch on and water birds can even roost in them if they are large enough!