Rain Gardens

Urbs Pluvialis  The Rainy City

The Problem:

The average urban home is surrounded by impervious surfaces such as roofs, concrete sidewalks, asphalt and even grass lawns.  When the rain falls, it hits these surfaces and most of the water keeps moving, carrying toxins, pollution and an overflow of water toward the storm drains and sewer system.  The sewer system, in turn, becomes backed up and pollutes the local water ways.  The excess surface water also can cause erosion and flooding.  Luckily, there is an easy way to capture the rain and make better use of it.    

Rain Wise

The Solution:

Rain gardens absorb rainwater runoff and storm water overflow.  They create a basin that stores the water and slows percolation, allowing for total absorption into the soil.  The filtration process that occurs when water passes through the soil actually cleans the water and removes pollutants.

How it works: The key is to make a garden that is permeable and absorptive.  This is not your average veggie or perennial garden.  A rain garden must be placed in a specific spot in your yard where it will capture rain water running slightly down hill from your home and at least 10 feet away from any structural foundation.  It is best to use a flat area in partial to full sun that is not near a septic field, or right under a tree.

Rain Wise

How to build one: Before starting out, test the drainage capacity (watch the area in a heavy rainfall or dig a few holes to fill with water and observe the rate of absorption).  The placement of the rain garden can be either directly connected to your gutter (with the help of a length of pipe if necessary) or it can be placed in an area where it will catch runoff from other parts of your yard (e.g. at the bottom of a grassy lawn).   After calling to determine utility lines, dig out your rain garden (initially about 100 square feet and about 8 inches deep for the average home).  In order to maximize permeability, fill the bottom layer of the garden with crushed gravel, followed by compost-enriched soil and topped with mulch or shredded leaves and shredded wood.

What to plant: Natives.  You want your rain garden plants to do well in any season (in the northwest, the plants must be able to absorb heavy and consistent rain all winter followed by several dry months in the summer).  Look for plants with large and deep roots that will be most absorbant.  It's best to use established plants so that the root systems are already strong and ready to work in the rain garden.  The Brooklyn Botanical Garden has a good list of rain garden plants by region.

City Perk:

The city of Seattle is offering a 80-100% rebates for residents who install rain gardens in certain areas.  Watch this clip from King 5 News for more information:

What else you can do:

If a rain garden just won't work in your yard, there are a few other ways you can help prevent water runoff and pollution.

1. Buy a rain barrel or cistern to attach to your downspout.  This will store up filtered rain water for your personal use as needed.  Place small rocks around the barrel or cistern to catch any overflow.
2. Place small rock-filled trenches under downspouts and at the end of driveways to catch runoff.
3. Replace driveways and patios with porous pavers or at least replace of your impervious areas with green material to increase absorption capacity.
4. Install a green roof to absorb rain water before it even hits the ground.
5. Add compost and top dressings to your beds. This will increase the absorption rate of your plants and the compost will actually store many times its weight in water and keep your plants hydrated even when the rain stops.

Rain Garden Resources:

Rain Wise (Seattle Public Utilities)

Healthy Landscapes (University of Rhode Island)

Low Impact Development

Anne Lovejoy's Handbook of Northwest Gardening (Sasquatch 2003)

Northwest Flower and Garden Show 2010

Show Stoppers

The Northwest Flower and Garden Show bustled through the Seattle convention center from February 3-7th.  There were 23 display gardens, filled with potted plants buried in sawdust and mulch to keep them fresh.  It took one week to set up the show (taking 1,200 cubic yards of sawdust and mulch and 280,000 pounds of rock to do so).  There were also around 300 exhibitors selling merchandise for every gardener's need.  Still, new ideas and information are really the highlights of the show.  So here are a few of my favorites:

"Reduce, Reuse, Recycle"

The recession has inspired a recycling revolution that was seen in many garden displays and throughout the flower display and garden marketplace.  I've highlighted some green ideas that are easy to use and incorporate into your garden.

1. Green Roofs
A low maintenance way to control temperature and prevent storm water runoff; there were several examples of green roofs this year but my favorites were the ones topping chicken coops--an eco-friendly way to help keep chickens comfortable.

2. Structures made from Recycled or Found Materials
I saw retaining walls and garden structures made from both stones found on site (dug up during garden projects) and from recycled materials (old concrete patio used as a table base).  The structure of the cages allowed the found rock or concrete to come in a variety of sizes since the cages held the pieces together.

3. Recycled glass adding warmth
This cold frame, which keeps fragile plants safe from the cold and is good place to start growing seeds outside, can be constructed easily--just make a lower bed box and attach an old window from your house (or from a local shop selling used ones).  Make sure the paint is lead-free and that there is an air vent that can be opened easily to prevent the plants from becoming overheated.  This is all you need to get a head start on your veggie growing!

Wine bottles held in place with cobb (clay, silt, straw, and water) also make a great heat inductor.  This structure will use heat from the sun to encourage growth and fruit production and keep plants warm in the fall and winter.  On a related note, a friend of mine had success with her veggies after creating a raised bed and lining the outside of it with pieces of slate to attract the warmth of the sun.

Living Walls

Hardy plants and dense ground cover filled the many living walls I saw this year.  Living walls can be used for decoration or function and construction and they are a great way to add green space to a small garden.

1. Living Fences

The display garden pictured above used hardy strawberries to break up the wooden fence that surrounded its garden, maximizing the space.  

 

2. Garden Soxx

Most impressive were the Garden Soxx; sold by Applied Organics and filled with Cedar Grove compost.   Each garden sock is three feet long and made of polypropylene. On the commercial level, they are used for large scale re-vegetation, erosion prevention and flood walls.  In your residential plot, they can be used for retaining walls, planters and natural structures.  The compost filled socks can be filled with seeds or plant starts and over time, the plants will spread and cover the structure.  The roots system that develops in the socks secures the foundation so even when the socks disintegrate (5 to 10 years, depending on sun exposure), the structure remains intact. 

Urban Farm Animals

Keeping animals has become a more accessible and realistic dream than ever before. Chicken and goat populations are scattered through urban neighborhoods, providing homeowners with fresh animal products and the joys and benefits of small urban farming.

1. Chickens
There were three active chicken coops on display this year. Chicken coops can greatly vary in shape and size so it is simple to find the right one for your yard. Two of the three had green roofs (the one pictured directly above is used for growing wheatgrass--with grinder on hand!), and one display featured the chicken tractor which is mobile and floorless. The mobility allows you to move the chickens to continually provide them with fresh vegetation and it will help spread the manure they deposit around your yard. In Seattle, an average plot is allowed three chickens.

2. Goats
Goats are another popular urban farm animal making their debut at the Flower and Garden Show. They provide milk and help clear out unwanted vegetation (or anything else that gets in their way!).  Three miniature goats are permitted per city plot in Seattle with a few restrictions--all must be dehorned and males must be neutered.

The Northwest Flower and Garden Show is an excellent place to gather ideas and get a good deal on gardening merchandise.  The entry price tag is high but early bird tickets can be purchased at a discounted price (up to one day before the event opens) and half day discounted prices are available every day.
 

See Northwest Flower and Garden Show for more details on the show.

Display Gardens and Merchants photographed:

Reduce, Reuse, Recycle: 1) Washington State Nursery and Landscape Association  2) Le Jardin Design and B. Bissel Contractor; 2-4) NW Bloom and Seattle Tilth

Living Walls: 1) Washington State Nursery and Landscape Association 2) Applied Organics, Inc.

Urban Farm Animals: 1) Seattle Urban Farm Co. 2) NW Bloom and Seattle Tilth

Final Photo: Seattle Urban Farm Co.

Compost!

Compost!

Soil too sandy?  Add compost.  Soil has too much clay?  Add compost.  Plants looking weak?  Add compost.  Veggie production down?  Add compost.  Sensing the pattern? Through my research I have learned of the great power of compost but now I will try to uncover what compost really is, why it is so effective and how it is made

Compost consists of decomposed organic material.  When added to your soil it replenishes the nutrients that plants leech out such as nitrogen, carbon, phosphorus and potassium.  Compost adds structure; grounding the roots of plants and keeping the soil aerated.  Compost can be beneficial to your soil at various stages of decomposition.  At its mature state, the rich black decayed material is called humus.  Nature has its own way of creating forms of compost (leaves fall in a forest and decompose on the forest floor, giving their nutrients back to the soil) but compost creation is often a bit more structured for the backyard or urban gardener.

Ingredients:

Balance of "greens" and "browns"

The most basic garden compost is made with a balance of "green" (high in nitrogen) and "brown" (high in carbon) materials.  Here are some examples:

Greens: grass clippings, chopped green leaves, flowers, coffee grounds, kitchen scraps, manure
Browns: shredded newspaper, wood chips, dead leaves, chopped plant debris

"Green" coffee grounds

Water and Air

Keep your compost moist with frequent watering and keep the materials aerated by turning the compost and use stakes or a pitchfork to create air pockets in the pile.

How to make your own

1. Pile o' debris
As you do yard work, stack the (chopped up and disease-free) debris in a pile.  Try to keep greens/browns balanced and keep the kitchen scraps out.  Turn the debris and water the pile occasionally and cover with cloth or a tarp.  Over time the debris will break down and give you nutrient rich soil amending material. 

2. Compost Bins
 These bins are relatively easy to make out of a wooden frame with each section usually measuring 3' by 3'.  The bins either have mesh siding (as seen above) or wooden slat siding (which will keep moisture in better).  It's best to place the bins, which will remain a permanent fixture in your yard, in an area that is easily accessible. 
Add equal parts of chopped up green and brown material together in one bin (the other bins can be used for unmixed materials or mature compost storage.  Keep the mixture moist with regular watering.  The organic matter must be mixed and aerated regularly.  If done properly, the compost cage will "cook" organic material at temperatures up to 130 degrees.  After the compost remains at 130 degrees for three days, all weed seeds and pests will be killed, so you have more flexibility in the materials you can put in the mixture.

3. Plastic Tumblers
The tumblers (equipped with a side crank) make turning the compost easier.  Other than that and their slightly neater look but higher price tag, the plastic tumblers are used in the same way as the compost bins.

    

4. Food Decomposing Containers

Kitchen scraps and chopped up yard waste can be turned into black gold by letting nature take care of itself in food waste digesters.  These are semi-permanent containers that compost on the spot and then can be moved to a new location once the process is complete.  A company called Green Cone makes a plastic container that is partially buried in the ground.  You can also make your own container out of a plastic or metal trashcan.  Just drill drainage holes around the bottom, partially bury it in your yard, and make sure the lid in on securely so no critters can get in!  Unlike the compost bin and tumbler, the food decomposing containers will not reach 130 degrees so weed seeds must not be placed in these containers.

 5. Indoor Compost Cookers

There are a few indoor composters on the market such as the Nature Mill, pictured above.  All you do is add kitchen scraps to the top and the machine will heat up and turn the material, producing usable nutrient-rich compost in a matter of days.

 

 6. For those without a yard

In Seattle, you can still do your part for the environment by disposing of your kitchen scraps in a biodegradable bag (which greatly limits the odor) and then throwing this bag in your city provided food and yard waste bin.  The food and yard waste debris is picked up by Cedar Grove Composting Company where it is composted at over 165 degrees for 45 days then at 130 for another ten days, allowing locals to put even dairy and meat products (materials that have harmful bacteria when not cooked at a high enough temperature).  See Cedar Grove Composting for more details.

Vermicompost

Worm bins are another great way to compost food and yard waste.  The bins are easy to make--outdoor versions are usually made of wood and indoor bins are made out of plastic.  Fill the worm bin with moist bedding made of newspaper, cardboard and leaves.  Add soil and worms to the mix (Red Wigglers are known to be the best).   Kitchen scraps must be chopped and then buried in small clumps around the bins.  Food scraps can be added several times per week.  As the worms eat the scraps they create nutrient rich worm castings.  The vermicompost is so potent that a little goes a long way on your yard and house plants.

Resources

The Complete Compost Gardening Guide by Barbara Pleasant and Deborah L. Martin

Guardening with Ed Hume by Ed Hume

Stuart Robertson's Tips on Organic Gardening by Stuart Robertson

Your Garden Soil by Harry Maddox

Guide for building compost and vermicompost bins from Seattle Tilth:

http://www.seattletilth.org/learn/resources-1/compost

Thanks to Seattle Tilth's great demonstration garden; open to the public and filled with examples of compost!