Aquatic plant selection is extremely important in the development of aquatic pools. You must have some degree of balance between plants and animals in your pool so that the water remains clear and major problems with maintenance and filters do not arise. Plants are very important in pools. They produce oxygen through photosynthesis, which allows maximum fish health. Plants also take up excess nutrients, particularly nitrogen and phosphorus wastes from the fish. In certain situations, ornamental pools can be stocked with only plants, with excellent results.
While numerous aquatic plants are available for water gardens, it is important to consider certain factors when selecting plants for a water garden. These factors include water depth, sunlight and how each species relates to its surroundings. You can obtain most plants from local garden centers or catalogs, but in many instances you can harvest wild plants for use in garden ponds with proper permission.
Four general types of plants are available for aquatic use:
- Submerged plants, also called oxygenating plants.
- Shallow water or bog plants, which grow along the water’s edge in natural environments.
- Floating plants, which are rooted in the bottom substrate and have floating leaves and flowers.
- True floating plants, which float on the surface of the water and whose roots are suspended in the water.
Two warnings should be heeded when selecting aquatic plants. Certain plants can become very invasive when planted under ideal conditions. These plants should be planted in pots, if they are used at all. Other plants are considered to be nuisance aquatic species.
The following plants are listed with South Carolina and federal agencies as illegal plants
- African oxygenweed (Lagarosiphon major)
- Alligatorweed (Alternanthera philoxeroides)
- Ambulia (Limnophila sessiliflora)
- Arrowhead (Sagittaria sagittifolia)
- Arrow-leaved monochoria (Monochoria hastata)
- Brazilian elodea (Egeria densa)
- Brittleleaf naid, (NajasminorAll.)
- Crested Floating Heart, Nymphoides cristata
- Common reed (Phragmites australis)
- Duck lettuce (Otellia alismoides)
- Eurasian watermilfoil (Myriophyllum spicatum)
- Exotic burreed (Sparganium erectum)
- False pickerelweed (Monochoria vaginalis)
- Giant salvinia (Salvinia auriculata, S. biloba, S. herzogii, S. molesta)
- Hydrilla (Hydrilla verticillata)
- Mediterranean clone of caulerpa (Caulerpa taxifolia)
- Melaleuca (Melaleuca quinquenervia)
- Miramar weed (Hygrophila polysperma)
- Mosquito fern (Azolla pinnata)
- Rooted water hyacinth (Eichhornia azurea)
- Slender naiad (Najas minor)
- Uraguary Primrose, (Ludwigia uruguayensis)
- Yellow Floating heart, Nymphoides peltata
- Water chestnut (Trapa natans)
- Water hyacinth (Eichhornia crassipes)
- Water lettuce (Pistia stratiotes)
- Water primrose (Ludwigia hexapetala)
- Water spinach (Ipomoea aquatica)
- Wetland nightshade (Solanum tampicense)
The oxygenating plants are submerged plants, which many individuals often overlook. You can plant them directly into the bottom, in pots, or simply weigh them down on the bottom. These plants offer excellent fish habitat and are major sources of oxygen in pools.
Shallow water and bog plants work best in containers. These plants are rooted in the bottom, grow above the water surface and generally have very showy flowers. They include cannas, irises, pickerel rush and other flowering aquatic plants.
Most water gardens utilize floating plants, which are rooted in the bottom. Examples of these plants are tropical water lilies, hardy water lilies, watershields and lotus. Tropical lilies are usually the best flowering plants. Some are day-blooming while others are night-blooming. When designing your pool, take into account when you will be viewing the pool. Tropical lilies cannot withstand cold temperatures and will either have to be grown as annuals or brought indoors during winter in South Carolina. Hardy water lilies are native to the area, and a number of varieties are available. The blooms are not as dramatic as the tropical water lilies, but they survive outdoors during the winter. The lotus can be a beautiful plant, but since it is known to spread rapidly and become invasive in natural ponds and lakes, it should be planted in pots. Watershield is also invasive and should be planted in pots.
True floating plants are generally not recommended in pools in South Carolina. They are the most invasive weed group.
The following Aquatic plants are recommended for South Carolina*
Submerged Aquatic Plants (“oxygenators” or oxygen-producing plants):
- Coontail (Ceratophyllum demersum)**
- Gray fanwort (Cabomba caroliniana)**
- Little floating heart (Nymphoides cordata)
- Tape grass or Eel grass (Vallisneria americana)
- Underwater banana plant (Nymphoides aquatica)
Floating Plants (deep-rooted aquatic plants with surface-floating leaves):
- Asian lotus (Nelumbo nucifera)** and American lotus (Nelumbo lutea)**
- Hardy water lilies (Nymphaea species and cultivars)
- Tropical water lilies (Nymphaea species and cultivars, such as N. capensis, N. colorata, N. gigantea, N. lotus, and N. rubra)
Shoreline, Shallow Water or Bog Plants:
- Bog bean (Menyanthes trifoliata)
- Club rush (Schoenoplectus lacustris subsp. tabernaemontani)
- Common arrowhead or Duck potato (Sagittaria latifolia)
- Corkscrew rush (Juncus effusus ‘Spiralis’)
- Creeping burhead (Echinodorus cordifolius)
- Egyptian paper reed (Cyperus papyrus)
- Elephant ear (Colocasia esculenta)
- Flamingo plant (Oenanthe javanica ‘Flamingo’)
- Golden club (Orontium aquaticum)
- Gray canna (Canna glauca)
- Hardy white butterfly ginger (Hedychium coronarium)
- Horsetail (Equisetum hyemale)**
- Japanese iris (Iris ensata)
- Japanese rush, Grassy-leaved sweet flag (Acorus gramineus)
- Lavender musk (Mimulus ringens)
- Lesser spearwort (Ranunculus flammula)
- Lizard’s tail (Saururus cernuus)
- Native water canna (Canna flaccida)
- Pickerelweed (Pontederia cordata) and Giant pickerelweed (Pontederia cordata var. lancifolia)
- Red-stemmed thalia (Thalia geniculata f. ruminoides)
- Scarlet swamp hibiscus (Hibiscus coccineus)
- Siberian iris (Iris siberica)
- Southern swamp lily (Crinum americanum)
- Spider lily (Hymenocallis caroliniana)
- Star sedge (Dichromena colorata)
- Swamp rose mallow (Hibiscus moscheutos)
- Sweet flag (Acorus calamus)
- Thalia (Thalia dealbata)
- Umbrella palm (Cyperus alternifolius)
- Variegated spider lily (Hymenocallis caribaea ‘Variegata’)
- Variegated striped rush (Baumea rubiginosa ‘Variegata’)
- Variegated water grass (Glyceria maxima var. variegata)
- Water arum (Peltandra virginica)
- Water bamboo (Dulichium arundinaceum)
- Water forget-me-not (Myosotis scorpioides)
- Water mint (Mentha aquatica)
- Water plantain (Alisma plantago-aquatica)
- Yellow water iris (Iris pseudoacorus)**
- Zimbabwe umbrella plant (Cyperus involucratus)
*The South Carolina Department of Natural Resources Aquatic Nuisance Species Program helps regulate the importation of non-native aquatic species into the state and should be contacted if any plants not mentioned in this list are to be brought into the state. Contact the Clemson Department of Plant Industry at 864-646-2140 or Chris Page at the South Carolina Department of Natural Resources at firstname.lastname@example.org.
**May be aggressive.