DIG THIS! Green Musings from GBG inc.

The Sheet-Mulching Legacy

Lava LampWhile we may roll our eyes at some of the regrettable fads of the 70s, one lasting legacy from that era is a heightened environmental awareness. It was during the 1970’s that a pioneering figure in the sustainability movement, Bill Mollison, began teaching the principles the movement that became known as Permaculture. Mollison, in collaboration with David Holmgren, drew on observations of nature and indigenous cultures to formulate an environmental ethic that placed care of natural systems at its center. Their goal became to design ecologically-sound and productive landscapes that would transform the global environment as well as the local community.


(photo credit: Pinterest)

One mainstay of Permaculture is a process called sheet-mulching. Sheet-mulching mimics the natural processes of soil formation, which depend on the accumulation and decomposition of organic matter over time. Think forests and woodlands: Under the thick layer of decaying leaves, twigs, and branches lies that earthy, sweet-smelling humus built to feed the trees and plants above.

If time permits in a home garden installation, rather than digging out weeds and disturbing the symbiotic relationship between the soil surface and the underlying micro-organisms, we use sheet-mulching to suppress weeds, conserve moisture, and increase the soil’s nutrient base–simultaneously. We stack thick layers of compost, organic matter, and cardboard over dead grass, water-hungry lawns, and bare patches of neglected earth to create an earthy sandwich, of sorts, that decomposes and becomes a field of healthy soil fit for planting. Humus in the forest takes decades to perfect, but sheet-mulching shortens those years to months. But don’t wait for us! This process is easy to research and can be your own first step in replacing a thirsty lawn with a drought-tolerant landscape.

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Making The Most Of The Rain

morro bay rain gaugeWe’re happy to say that our rain gauge was overwhelmed by our recent storms! No matter what the amount of rain we get this winter, we don’t want a single drop to go to waste. In order to replenish our precious underground aquifers, the rainwater must percolate through the soil rather than running off the surface. And while we cannot make it rain, we can make a difference in the amount of run-off.

Under natural conditions, soil acts like a sponge, soaking up and absorbing much of the rainfall. Vegetation and leaf litter break the momentum of falling raindrops, allowing the water to filter gently through the air spaces between individual bits of soil. When the earth is exposed, parched, and compacted, it’s as if the soil sponge has been squeezed dry. The pores and pockets shrink and close off, and it is more difficult for water to penetrate.

As much as possible, then, we work to direct rainwater into the ground. Mulching in the fall will protect the soil from eroding during our winter rainy period. The mulch slows the velocity and allows the maximum amount of water to collect and soak into the ground. Landscaping with swales and berms also helps intercept run-off and channel water back into the garden instead of into the street. Lengthening the time that the water remains on the land allows it to slowly seep into the ground, rehydrate the soil, and recharge our depleted groundwater basins.

Making the best use of any rain that does fall turns that water into a resource – one that we sorely need.

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“Mowing” The Drought-Tolerant Lawn

carex pruning

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Lawnmowing services exist to give homeowners a break from the tedium of hauling out the mower each week. The hassle, the sweat, the repetition–it seems worth it to shell out a few bucks to skip the mess of grass clippings and go right to the backyard barbecue. But even more convenient than paying someone to deal with your water-hungry lawn could be the brief task of clipping a native crop of Carex grass just once a quarter. 
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Gardens by Gabriel’s demonstration garden features a meadow of two types of Carex: Carex pansa (green) and Carex flacca (blue). Both were planted at the same time and have grown in happily with the help of low-flow drip irrigation. Six months later it was time for their first haircut. While we enjoy the look of a lush, flowering meadow, we like to clip younger grass clumps to encourage them to expand laterally and form a denser carpet. There are choices for how to cut grass, and we landed on hand pruning with a hedge shear because it avoids the need for a gas-powered machine as well as the burned edge left by weed-eating or weed-whipping.photo 2 copy 3photo 4 copy 2












As with mowing a lawn, mulching with the clippings is a healthy protocol (and a lot easier than gathering them into the greenwaste bin). We spread ours over the mulch and grasses alike with a metal rake and called it a day.


Tools: Shears, rake, funny hat.
Total elapsed time: 20 peaceful minutes on a Spring afternoon.





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California Native Plants and the Approach of Summer

san luis obispo native garden California native plants are known for their vibrant winter blooms, but also for their summer dormant season and for this reason are sometimes overlooked for Mediterranean gardens. It is possible to maintain a beautiful and water-wise garden year-round that includes California natives; all it takes is some strategy.

When they’re young, California natives can be treated like other plants in a cultivated garden: They need regular watering to establish a healthy root system. As natives grow to maturity at 5-10 years, you have two choices.

1. Embrace Dormancy:
If you water them less and let them go dormant, your plants won’t be as stressed by root rot and fungal outbreaks, and in general will live longer. With that in mind, combine grasses, succulents, shrubs, and trees whose color and texture vary throughout the year. Design your garden with a plant palette diverse enough to feature the seasonal peaks of certain plants while covering for those that take a break.Mediterranean Meadow

2. Irrigate:
Many Mediterranean and California native cultivars are now adapted to well-placed and well-timed summer irrigation. In order to not stress the plants, however (because too much water or nutrition is just as stressful as not having enough), it is important to carefully place and test every drip emitter. Making sure emmiters are spaced out from the plant crown will encourage wide root growth into the native soil, and discourage rot due to stagnant water. With the consistent encouragement of drip irrigation, most native trees and shrubs will dig their roots deep into the soil, find water, and thrive year-round.


As we embark on our passage through Spring and the last months of our unique growing season, enjoy your thriving garden and the natural landscape around us. Take in the lushness of the grasses, enjoy the vibrant colors in the succulents, watch the poppies and other annual flowers express their beautiful colors–and get ready to dial in your irrigation timers!

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Succulent Senecio

Happy coastal growers, Senecio are one of the most forgiving succulents when it comes to propagation. It’s time for us to start a new batch, so we’re going to take you through it step-by-step.








In order to start a new crop, clip the last 5″ of a plant that is doing well.












You’ll see that some of the “leaves” are quite close to the cut–these few should be removed. Snap these off and drop them in your compost pile.











You’ll be left with a cluster of leaves at the end and a 1.5 inch stalk.













Once you’ve amassed a collection, stack them on your potting bench.













Plop the newly-exposed stalks into a receptacle with at least 2″ of soil mix (we combine our home-grown compost with a little pearlite).











Water them in, keep them warm and safe, and wait for their roots to grow!












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Water Conservation Sweeping The Nation!

…Starting with our own KCBX!

Many thanks to Mike Bush of the San Luis Obispo Botanical Garden who, during his January 25th, 2012, interview on KCBX, mentioned a garden we completed with water conservation champion Mary Wilhelm. We were happy to be able to feature Mary’s garden in an article with the Tolosa Press, highlighting that due to her efforts to reduce her water usage, she hadn’t watered her garden at all during 2011. Take a listen to the SLOBG’s Executive Director as he discusses upcoming SLOBG events, signature qualities of Mediterranean climates, and the future of our inspiring local garden:

Mike Bush SLO Botanical Garden KCBX Interview 





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Barrel-Free Rainwater Harvesting in SLO County

Leonardo da Vinci said, “Water is the driving force of all nature.”

Rainwater harvesting might not be for everyone, but there are still ways to lessen rainwater runoff. We routinely use and recommend Bioswales to remove silt and pollution and slow the water for better ground absorption. A bioswale is the use of mounded earth to create a drainage course, which slows the water’s path and maximizes filtration. Thick layers of mulch and creative uses of earth also can be designed for the water to slowly sink back into the ground. (Ever rough up your nails before you apply that layer of glossy nail polish? Same thing!)

You may be wondering if rainwater harvesting is OK to do in San Luis Obispo County:

“City of San Luis Obispo 2010 Construction and Fire Code Amendments page 25: 1101.2.1 Rainwater Harvesting. Storm water drainage may be directed to an approved rainwater harvesting system and used an al alternate source of water for non-potable uses as approved by the building official and the San Luis Obispo County Environmental Health Department. The installation and use of such a system or systems must be designed to not interact with the potable water system, the building sanitary sewer or drainage systems that flow to any creek. Rainwater harvesting systems must be maintained in such a manner as to not cause damage to neighboring properties.”


Rainwater Harvesting Around the World:

· Currently in China and Brazil, rooftop rainwater harvesting is being practiced for providing drinking water, domestic water, water for livestock, water for small irrigation and as a way to replenish ground water levels.

· In Tamil Nadu, India, rainwater harvesting was made compulsory for every building to avoid ground water depletion.

· In Bermuda, the law requires all new construction to include rainwater harvesting adequate for the residents.

· In Senegal, the houses of the Diola-people are frequently equipped with homebrew rainwater harvesters made from local, organic materials.

· In the United Kingdom, “water butts” (water casks) are often found in domestic gardens to collect rainwater which is then used to water the garden.

· Until 2009 in Colorado, water rights laws almost completely restricted rainwater harvesting; A property owner who captured rainwater was deemed to be stealing it from those who have rights to take water from the watershed. Now, residential well owners that meet certain criteria may obtain a permit to install a rooftop precipitation collection system.

· In Australia, rainwater harvesting is typically used to supplement the reticulated mains supply.


Beyond Rain Barrels

Remember Grandma telling you that washing your hair in rainwater made it softer? If we look back a generation or two to Grandma’s time, almost everyone had a rain barrel. Despite the benefits of collecting the yearly downpour, however, rain barrels in our area often don’t collect enough water to last through our lengthy dry season. 
What to do?
If you have some extra space and are able to invest around $20,000 you can have your very own rainwater harvesting system that’s efficient to water your garden all year long. That’s a lot of output up front, but the savings over time are many, and you’d be doing our water stores a great service! Generally a 5,000 gallon tank is needed to collect enough water for Central Coast climate. Your garden will love rainwater just as your hair would, because it’s free of salts and harmful minerals and doesn’t have to be treated. 

Slow it, Spread it, Sink it!

“We forget that the water cycle and the life cycle are one.”
Jacques Cousteau
Today we find sea levels rising, aquifers being depleted, snowpacks shrinking, and water supplies dwindling. We seem to be increasingly oscillating between periods of intense rain and drought. Many areas have been identified as places where surface and groundwater supplies won’t be able to meet future demands. If only there were ways to harvest rainwater and save it for drier times or to make the ground better able to absorb the water when we get it…
Luckily, there are!

Traditional building and landscaping practices were designed to dispose of stormwater as quickly as possible. We now know this results in significant damage to land, structures, and our surrounding environment. Instead of rainwater disposal, we’re advocates of the “slow it, sink it, spread it” approach. 
  • SLOW IT: Use land forms, berms, boulders, etc, to slow down rushing runoff
  • SPREAD IT: Reduce runoff volumes by distributing stormwater across gravel, swales, or permeable pavement
  • SINK IT: Increase retention of water by sinking it into the ground with thick mulch beds, earth basins, and more

San Luis Obispo Visiting Bioneer

Press Release from Central Coast Bioneers:


FOR IMMEDIATE RELEASE    September 06, 2011

International thought leader asks,What if every act of design and construction made the world a better place?”

Public invited to attend.

Green building expert Jason McLennan to present in San Luis Obispo

San Luis Obispo—Jason McLennan will be in San Luis Obispo on Friday, October 14, 2011 to discuss concepts from his fascinating new book, “Zugunruhe,” and share powerful examples of ‘Living Buildings’ emerging around the US and Canada. Members of the public are invited to attend. The event is a benefit for California Central Coast Chapter U.S. Green Building Council and Central Coast Bioneers.

McLennan was recently named one of the top 40 under 40 most influential individuals in the design and construction field by Building Design and Construction magazine. He is presenting as a featured speaker at the annual Central Coast Bioneers conference, produced by local non-profit Ecologistics, Inc.

Location: SLO Vet’s Hall (801 Grand Avenue, San Luis Obispo, CA 93401)

Sponsored by: Alma Rosa Winery and Vineyards, the Hearst Lecture Series at Cal Poly, and Solarponics

Event Details:

  • Reception: 6pm – 7:30pm
  • Lecture: 7:30pm – 8:30pm
  • Book Signing: 8:30pm – 9pm (Mr. McLennan will sign two of his books, “Zugunruhe” and “The Philosophy of Sustainable Design”.)


  • Reception and lecture $45 (benefit for California Central Coast Chapter U.S. Green Building Council and Central Coast Bioneers)
  • Lecture only, $20
  • Students: $4
  • Please register in advance
  • Free for Bioneers Conference Total Immersion Pass Holders

Register online at https://register.ecologistics.org or call (805) 548-0597for mail-in/fax-in registration form.

“What if every act of design and construction made the world a better place?”