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By caring for your wetland plants, you will magnify the level of treatment.
THEIR FUNCTION: Constructed wetlands began with the observation that certain marsh plants, like cattails and bulrush, have special tissues that transport oxygen to the root zone. Oxygen is the driving factor for wastewater treatment by promoting the growth of microorganisms which transform the elements in our waste. Plants also take up water and nutrients in wastewater for their own growth, as well as provide beauty and habitat.
THE DESIGN: When you think about your plant design, keep in mind that the main objective is to create a deep, consistent root zone. We suggest using papiro, cattails, rushes, and wetland ferns in the center, or in the first cell if you have two, because they grow tall and provide most of the treatment. Surround them with other flowering plants with good root structure, like birds of paradise or elephant ears which take up a lot of water. Decorative flowers may be used on the edges. Perhaps you prefer the look of some of the groundcover plants or vines, but watch that they don’t become invasive. In general, bushes and trees have unsuitable root structure and should be used sparingly. Do not plant anything above the PVC tubes (front and back edges), and the plants adjacent to the tubes should have shorter roots (elephant ear) to avoid clogging. Native plants are the best.
COLLECTING: We suggest manually collecting the marshland plants like cattails, bulrushes and reeds because they are rarely found in nurseries. Plus, you will be able to see the real ecosystem at work! Be conscious of where and how many plants you take from the wild―just be an observer in sensitive wetlands, lagoons, and mangroves. Most of the plants you need can be found in puddles or disturbed areas by the side of roads. Submersed plants like cattail are easy to uproot―just pull! Try to not break the root. Look around–are there decorative plants or grasses that may be suitable? Take them back home and try to transplant them as soon as possible or keep them in a little water. Cut off the leaves, leaving only 5-10 inches of shoot.
PLANTING: If possible, plant the wetland when it is filled with tap water. If not, be very conscious of wastewater contact when planting. Dig the holes and place the roots as deep as possible. For plants from a nursery, remove them from their container, shake out the extra dirt that isn’t surrounding the roots, and see if you can easily separate it into two or more plants! Spread out the roots carefully and place them in the hole.
SPACING:
Cattail, rush, elephant ear, papiro: 6-8”
Wetland ferns: 12”
Lily, smaller flowers: 4”
MAINTENANCE: Cattails and bulrush are typically pruned back several times a year to promote new growth. As your wetland evolves, you may have to remove plants that have become too dense, or that have been introduced. Keep the area over the PVC pipes and control box free of weeds. Try to remove them by the root. Equally, watch for dieback or empty spaces that need to be replanted. Do not be afraid to work in your garden, being conscious of direct contact with wastewater on hands or feet, and washing yourself well afterwards.
CONSTRUCTED WETLAND
PLANT SPECIES
Questionable Trees/Shrubs
Washingtonii robusta Washingtonii Palm
Cocoloba uvifera Sea grape
Thrinax radiata Chit
Conocarpus erectus Botoncillo, buttonwood
Chamaedorea seifrizii Palma camedor
Croto Croto
Carica papaya Papaya
Trees/Shrubs That May Be Sparingly Used
Copa de Oro
Ixora coccinea Ixora
Nerium oleander Oleander
Musa sp. Platano, banana
Lantana sp. Lantana
Zone I Marshland Plants
Typha dominguensis Tule, cattail
Eleocharis cellulose Sedge
Phragmites australis Reed, Carrizo
Cladium jamaicense Sawgrass
Equisetum
Juncus roemerianus Soft rush
Cyperus ligularis Zacate cortadera
Acrostichum danaefolium Helecho, wetland fern
Xanthosoma roseum,
Alocasia macrorhiza Mafota, elephant ears, taro
Zone II – Flowering Plants
Heliconiaceae sp. Heliconia
Hymenocalyx littoralis Spider lily
Canna edulis Platonillo, canna lily
Irlbachia purpurascens Lila de campo
Portulaca oleracea Verdolaga, moss rose
Bidens pilosa Margarita
Vicaria, Mananita, Teresita
Zone III – Ground Cover and Vines (opt.)
Ipomea pes-caprae Rinonina
Scindapsus aureus Telefono
Kate Riley
February 2004
To read this in Spanish click here.
A Manual of the Operation & Maintenance of Constructed Wetlands click here.
To learn more about constructed wetlands click here.
To learn more about our Advanced Waste Treatment program
click here.
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