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

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

Without water we wouldn’t have gardens.  Water brings our gardens and landscapes to life.  When the concept of gardens designed purely for pleasure in the ancient cultures of the Middle East, water was a precious resource.  Some of the early gardens represent a lush green (water-fed) vision of perfection to an arid surrounding.  Water has always been a magnet, an indispensable ornamental element in gardens, and now, more recently, the presence of water has been seen as essential for creating a balanced habitat, a bird friendly garden to attract wildlife as well as providing pleasure for people.  Water is a finite and unpredictable resource and is now the epicenter of our planning and design thought process for our gardens and landscape.  Ultimately, the presence or absence of water dictates what is possible.

Technically, a rain garden is a very specific, planted depression that is designed to take all, or as much as possible excess rainwater run-off from the non permeable pavement, house or other building and its associated landscape.  In this series, I will use a more evocative approach, with a broader definition, covering more possible elements that can be used to capture, channel and make the most of the natural rain fall.  The idea is that all of the individual elements that we deal with are small-scale rain gardens in themselves.  Rain gardens promote planting and the more diverse or complex the planting, the greater the benefits.  Replacing paved surfaces or intensively managed turfgrass with mixed naturalistic planting will greatly increase the wildlife and habitat value of a garden.  

Although native plants make a major contribution to this naturalistic planting, rain gardens include plants from other regions, and when natives, flowering perennials and grasses with scattered shrubs are designed properly, you will create an ideal mix for encouraging a great diversity of wildlife.  Reality speaking, garden biodiversity is not the just the visible and attractive things we like- birds and butterflies, it is about the things we can’t see- insects and invertebrates, hidden in the soil or vegetation.  Rain gardens are particularly useful for supporting that greater biodiversity.  Next blog I will discuss Stormwater Planters, methods and techniques.

If you have any questions or would like to read on other sustainable topics pertaining to the landscape, please email me at eric@florapacifica.com

Xeriscaping- Just The Facts

Xeriscaping (NOT ‘Zero-scaping’) is a method of water-prudent landscaping created by the Denver Water Department in 1978 and is a registered trademark of Denver Water.

The word xeriscaping is a portmanteau of xeros (Greek for "dry") uses plants that are tailored to the native climate of a region, coupled with other water-saving design ideas.  In many cases, especially in the West, this means getting rid of thirsty plants and sod in favor of more drought-resistant foliage.  In a conservative community such as ours, some people just don’t want to let go of traditional landscaping, but with the ever rising water and sewer rates and the fact that 50% of our potable drinking water is used to irrigate our landscape, it is time to break away from this traditional thinking.  Xeriscaping, when implemented correctly and with knowledgeable professionals, can decrease your landscape water usage by nearly 45% within 3 years.  Another large benefit of a xeric landscape over a traditional landscape is the reduction in maintenance costs.  On an average, you will reduce the time necessary to maintain a xeric – style landscape and reduce maintenance costs 30% over a traditional landscape.  As your xeriscape landscape matures, your time management will allow you to do more enjoyable things for the day to day maintenance will continue to decrease.

Xeriscape just looks more harmonious, more in tune with the landscape of the West overall.  We can show people there are exciting and colorful waterwise plants available to the consumer, plants that are very colorful and appropriate for our climate and elevation and the results will be aesthetically pleasing and rewarding.  Rewarding in a sense of ecological responsibility and knowing that your xeriscape is fire wise, attracts charismatic wildlife and saves water while increasing your investment.  A Waterwise landscape is also rewarding in your pocket book as well since the average cost per square foot for a xeriscape garden averages out to be nearly $1.89 per sq foot less than a traditional landscape.  Water conservation is becoming a normal way of life, especially in the west as groundwater reserves are being depleted and communities are forced to look beyond their borders for viable water sources and this can lead to conflicts with other communities.  Xeriscaping is quickly becoming the normal and responsible means of landscaping and not only in the West, but in other regions of the country as we just aren’t getting enough consistent and reliable rainfall from year to year.

Sustainable Gardening in Small Spaces

Choosing the right layout (shape) of your garden will save space, reduce labor, and create a better balance for plants and pollinators.  The shape of a garden determines how much area can actually be planted, sustaining a healthy environment to maximize annual production.  For example traditional hedgerow gardening ‘pathways’ can consume a large amount of your planting area opposed to thinking outside the proverbial box and planting in a natural pattern where pathway usage is reduced 8 fold. 

Vegetable and herb gardens do not have to be planted in straight rows, they can have curves and movement and in some cases vertical movement (as I will explain a little later).  Constructing a planting area in a round shape with a central pathway can maximize a small space and offer a great diversity of planting options.  Referring this type of planting as a ‘zone’ system, the plants that are harvested frequently should be planted closest to the pathway.  This would include your herbs for instance.  The second course you would then install vegetation that gets picked regularly over the growing season, such as your tomatoes, eggplant and beans.  Finally your outer area would be the ‘one and done’ plants such as potatoes, lettuce, etc.  This type of gardening creates endless possibilities and as I have found, being creative not only adds excitement to something that may normally fee mundane and repetitious from year to year. 

There is no limit to design and creative possibilities such as planting small fruit trees and perennial nitrogen-fixer plants that could provide good wind-and-weed barriers.

Now let’s think totally outside the box and maximize a very small space to build a spiral herb garden 5’ across at the base rising to a height of 3’ above grade.  A spiral garden approximately 5’ across by 3’ in height would equal 27 linear feet of pathside plants.  To construct this style of garden, all you need is a mound of good soil and some melon sized boulders inserted in a spiral pattern winding inward from the bottom.  By constructing a vertical greenspace, you have now created slopes that face in all directions, providing you great versatility in your herb choices, ranging from part sun / shade to full sun.  Also, the soil at the bottom of this spiral will stay wetter than at the top, so plant accordingly and have fun this spring with your creative side and get the children involved.  

If you would like more information on different multipurpose plants, please email me at eric@florapacifica.com and visit us at our http://twitter.com/florapacifica

Tree of The Week: Amelanchier laevis ‘Spring Flurry’

Botanical:  Amelanchier laevis ‘Spring Flurry’

Common:  Spring Flurry Serviceberry

Plant Details:     Semi-Desert Plant Community

                        Medium Street Tree 20’ Spread x 28’ Height

                        Sun to Part Shade

                        White Cluster Blossoms in Spring

Dominant Central Leader

                        15-20” inches of Annual Precipitation to Establish

Habitat Facts:    Street Tree

                        Bird Cover, Food Source

                        Edible 3/8” Berries Provide Banquet for Birds 

                        Hardy to Zone 4

General Notes:   Perfect Medium Tree for Bird Habitat, Naturalizing

Does Not Like Alkaline Soils

Maintenance Tips:  Prune Interior Branches after 5 Years

Please send in your questions to eric@florapacifica.com and answers will be posted in next week’s blog post