Rain Gardens: How to Sustainably Manage Water in Your Designed Greenspaces (Second in a Series)

Stormwater Planters

It is easy to come across as being pious and sanctimonious when dealing with environmentally – friendly design, and also to be perceived as spreading dire messages of impending disaster if we don’t change our ways.  The need to create greater environmental awareness in dealing with water conservation is evident and by implementing some of these simple principles such as stormwater planters and rain water harvesting, it gives real meaning to all the decisions that we make about how a landscape is planned and we are doing something positive which we have control.  



Stormwater planters are exciting and relatively new development in rainwater management.  They were pioneered in Portland and are described in the Portland Stormwater Management Manual (2004) as ‘structural landscaped reservoirs’.  They are essentially above – ground boxes partially filled with soil in which plants are grown (ref. photo).  These planters provide a means of bringing planting and vegetation into the smallest of schemes and offer a creative alternative to the ubiquitous foundation planting at the base of your home.


Stormwater planters take rainwater straight from the structure’s roof as the downpipes empty directly into the planters.  If the inflow rate exceeds the infiltration rate, then ponding will occur near the top of the wall level, allowing this water storage to attenuate flow.  Excess water can then exit the planter at the overflow near the top of the planter diverted into other vegetated areas adjacent the stormwater planter, infiltrating into the ground.  The design aim is that water does not remain in the planter for more than 12 hours- preferably draining through the planter within a 2-6 hour window, reducing the possibility of anaerobic conditions, which are detrimental to plant growth.

Stormwater planters create more than just an opportunity for rainwater management and planting, they allow us to think of these structures as ways to organize and arrange outdoor space.  Next week we will discuss various rain water harvesting methods and formulas for calculating how much water you can harvest.  Please follow us on Twitter:  Http://twitter.com /florapacifica