The Professional Design Guide to Green Roofs

I picked up The Professional Design Guide to Green Roofs at the San Francisco Garden Show several years ago, after attending a presentation by two of its authors. Green Roofs was written by Karla Dakin, Lisa Lee Benjamin, and Mindy Pantiel, and published by Timber Press (Portland, Oregon 2013). The authors are professional landscapers with portfolios of significant roof top and ground-based landscape projects, and a network of roof top landscapers around the world.

Green Roofs is comprised of two sections. Part One: Inspiration—Form and Function describes finding inspiration for designs from nature and culture. Chapters include Shapes and Patterns, Creating Living Spaces, Wildlife Friendly Spaces, and Plant-Driven Environments. Part Two: Process focuses on project management for the professional landscaper. Chapters take the reader through the processes of predesign, site analysis, client program, planning and conceptual design, design development and construction, and contracts, construction, and maintenance. The final chapter, The Evolving Frontier of Landscape Design, casts vision for the future of roof top gardens in the urban landscape. The back matter includes a bibliography, acknowledgments and credits, a chart of USDA climate zones, and a thorough index.

The book is filled with beautiful photographs that illustrate concepts and serve as a portfolio of projects installed by the authors and other green roof landscapers. Their projects include both living spaces and living meadows, depending on the weight the roof can bear. I especially appreciated learning about the the move toward providing green roofs in the urban settings for practical reasons, like filtering rain water, lowering the heat island effect, and providing a habitat for pollinators and migrating birds (imagine an aerial wildlife corridor through busy cities where migrating birds can touch down for rest and nourishment). Green roofs can also provide a space for city dwellers to seek respite from urban life, and enjoy fantastic views.

I was also pleased to see some favorite titles in the bibliography, like Thomas Church's Gardens are for People; Theodore H. Osmundson's Roof Gardens: History, Design, and Construction; and Tim Richardson's Futurescapes: Designers for Tomorrow's Outdoor Spaces (as well as many other new titles to explore). With a growing population and spreading cities, the ancient idea of green roofs is a timely vision for the future.

Mordanting Fabric (Alum Brightener)

In this episode of Plants to Dye For - Season 2, we're using a combination of alum and soda ash to mordant our fabric. In previous episodes we scoured the fabric [see Scouring your Fabric (Soaking Method)] and mordanted the fabric using oak gallnut [see Mordanting Fabric (Oak Gallnut)]. You may wonder why we are re-mordanting our fabric. Dyers frequently mordant fabric multiple times to intensify the color or improve colorfastness. For example, after mordanting with an oak gall tannin, a dyer might mordant with an alum bath of 15% WOF, followed by a second fresh alum bath of 10% WOF.

I'm using alum and soda ash (also called washing soda), both of which I purchased online. Together the alum and soda ash act as brighteners. Alum (or Potassium Aluminum Sulfate) also prepares the fiber to bond with the dye. Soda ash (or Sodium Carbonate) changes the pH of the water, and can be added for dyes that respond to a higher pH level.





The basic process, based on Maiwa's online instructions (How to Mordant Cellulose Fibres):

1. Presoak the scoured and mordanted fabric. 
2. Mix alum and soda ash in hot water. 
3. Add fabric and soak. 
4. Rinse and air dry the fabric 

Stainless steel pot

Bucket for soaking and optional thermometer

For equipment I'm using a large plastic bucket for presoaking, a stainless steel pot for soaking, and optionally I can use a candy thermometer to check water temperature. Maiwa recommends using hot water between 120-and-140 degrees Fahrenheit (or 48-and-60 degrees Celsius). For this technique, you do not need to “cook” the fiber. You can start with hot tap water, and let it cool naturally. It is not necessary to reheat the bath to maintain temperature. For safety, wear a face mask when measuring powders, so you don't inhale small particles.

Alum and soda ash for second mordant

According to Maiwa, the Weight of Fabric % for the brighteners is:

• 15% WOF for Alum
• 2% WOF for Soda Ash

We have just over a pound of fabric, or 448 grams, so we'll use:

• 1/4 cup of Alum (67.2 grams)
• 1 3/4 teaspoons Soda Ash (8.96 grams)
• 2-4 gallons of water (I used about 3 gallons)

First, soak the pre-washed and scoured fabric in a bucket of hot water for at least and hour (or overnight). This helps ensure that the fiber soaks up the alum brightener evenly.

Soak the scoured and mordanted fabric

After pre-soaking the scoured fabric:

1. Add the fabric to the stainless-steel pot. 
2. Dissolve alum in hot water and add to the pot. 
3. Dissolve washing soda in hot water and add to the pot. 
4. Fill the pot with enough hot water to cover the fiber. (If you are curious, you can check the temperature with the thermometer). 
5. Stir. 
6. Let soak for 1-2 hours. You can cover the pot so that it stays warm. 
7. At this point you can: (a) Rinse and re-mordant, for example, at 10% alum. (b) Rinse and dye. (c) Steep an additional 8-24 hours. (d) Air dry, to dye later. 
8. I continued to steep the fabric overnight, stirring periodically. 
9. Squeeze out excess liquid. Soda ash is caustic so wear rubber gloves. 
10. Wash and rinse thoroughly in the washing machine, and hang to dry.

Air dry fabric

Now you can dye your fabric, or store it until you are ready to dye. According to one source, the alum can weaken the fiber, so it is best to use the fabric within a month to prevent this. For this video, we are labeling the fabric for storage, with plans to dye in a couple of weeks.

Label and store the fabric

Calscape

In his Bring Back the Natives keynote, Dr. Douglas Tallamy spoke on what we can do to attract and sustain nature in our yards. He invited us to think of our yards as being part of the food web, and collectively as part of a wildlife corridor for migrating or nesting birds. By planting hosts for the kind of food that birds, insects, amphibians, and animals need, we help ensure their survival. For example, here in the Bay Area, the oak tree is a key host in the food web. Dr. Tallamy mentioned two tools for figuring out what to plant – Calscape and Native Plant Finder (in Beta).

Calscape is especially good for those of us in California, and the San Francisco Bay Area where we have so many microclimates. The data is sourced from familiar plant databases, such as Jepson, CalFlora, California Native Plant Society, Wikipedia, and many more. You can enter your zip code or address to filter data specifically for where you live, for example 94611.

Calscape in a browser – enter a zip code or address to get started

Native plants filtered by category for the zip code entered

We have a live oak in our yard (Quercus agrifolia), and I'd like to learn more about what it contributes to the food web. Select Trees > Coast Live Oak to dive in.

Native trees for the zip code

From there, I can learn all about the oak tree in my yard. Including all the butterflies and moths it hosts, which provide a generous food source for birds and other creatures.

Butterflies and moths hosted by the oak tree

Another great feature is that you can create plant lists as you research. I started an inventory of native plants that I find in my yard. I still have work to do.

Plant Inventory of our yard in Detail view

I also started a list of native plants to introduce into the garden, and downloaded it in spreadsheet format. I can also access the information through Calscape running in a browser on my mobile phone. Calscape also links to native plant nurseries in the area, making it easy to find out what plants are available and where.

Plant Wish List in Grid view

Spreadsheet version for easy access 

I highly recommend Calscape as a resource for those of us who garden here in the Bay Area, or anywhere in California. You can use it without an account for general research, but can add a free account to use some of the features like creating lists.

Mordanting Fabric (Oak Gallnut)

Welcome back to Plants to Dye For – Season 2! In this episode, we're using ground oak gallnut as a mordant for our fabric. Mordants help bind dye to fiber, and improve color fastness. We learned about mordants last year (see Mordants and Fixatives), and used gallnut as a mordant for our weld project (see Dye Project: Weld Extract). Now we'll go a little deeper into the details of mordanting. This year I'm experimenting with processing dish towels in advance, so I have a large quantity on hand for projects.

I'm using oak gallnut extract from Maiwa. Gallnut is a clear tannin, and made from ground oak galls, which are rich in tannins. The galls are harvested, dried, and ground to a powder. Oak galls are created by parasitic wasps, which use genetic engineering to create their nurseries.





The basic process (based on Sasha Duerr's The Handbook of Natural Plant Dyes):

1. Presoak the scoured fabric.
2. Simmer the gallnut in water.
3. Add fabric and soak.
4. Rinse the fabric in cold water.

Stainless steel pots

For equipment I'm using a large plastic bucket from the hardware store, a large stainless steel pot, a candy thermometer, and a heat source. Last year, one of my aluminum pots was stained from onion skin dye, and the color may have influenced the outcome of the weld dye color. This year I thrifted a couple of stainless-steel pots, which should help prevent color transfer. The candy thermometer is important because the mordant works best if the tannin bath temperature does not exceed 180 degrees F (or 82 degrees C). You can work in the kitchen for this project, but always ensure ventilation. For safety, wear a face mask when measuring powders, so you don't inhale small particles.

Oak gallnut extract for mordanting fabric

According to Maiwa, the Weight of Fabric % for gallnut is:

• 12% WOF for Gallnut powder
• 6-8% WOF for Gallnut Extract (which we are using)

We'll use 8% WOF for our dish towels and T-shirt. We have two batches of towels, each weighing just over a pound or 462 g. For each pound of fabric:

•  3 tablespoons powdered oak gall extract
• 2-4 gallons of water (I used about 3 gallons)

First, soak the pre-washed and scoured fabric in a bucket of hot water for at least and hour (or overnight). This helps ensure that the fiber soaks up the gallnut evenly.

Soak the pre-washed and scoured fabric

After pre-soaking the scoured fabric:

1. Place the gallnut extract in a pot of water, and stir to dissolve.
2. Bring the tannin solution to a simmer, keeping it under 180 degrees Fahrenheit (or 82 degrees Celsius), and then simmer for 30-60 minutes.
3. Remove the tannin pot from the heat and let cool.
4. Lift the dish towels out of the soaking pot, squeeze out excess water, and add them to the tannin pot.
5. Steep the towels in the tannin pot for 8-24 hours.
6. Rinse the towels thoroughly in cool water, and then use the rinse and spin cycles on your washing machine.

Multiple batches of pre-processed fabric hang to dry

At this point, you are ready to dye the wet fabric; further treat it with an alum brightener; or hang it to dry and store the fabric until you are ready to dye. For today's video, we are labeling the fabric for storage, with plans to dye at a later time.

Label and store the fabric

In closing, I've found that none of these processes—like scouring and mordanting—are difficult. But they take time, often stretching over several days if you use the maximum recommended soaking time. Much of that time is spent soaking the fabric in various baths. I'm hoping that processing several batches early, will save time later when I'm ready to dye.