Cucumber patch July 13 after spider mite attack

  • The Nurse Tree Arch continues to welcome visitors and support other gardeners:
    • Deb Miller, aide to County Supervisor Sharon Bronson, provided Michael with contacts working on "extreme gardening" issues in the town of Ajo, 90 miles west of Tucson and adjacent the Cabeza Prieta National Wildlife Refuge. This is the land of ephemeral water and the storied El Camino del Diablo, the Road of the Devil. Growing conditions in Ajo easily pass into the realm of the extreme. Michael hopes to make contact soon with these resourceful people.
    • Scott Rosenbaum introduced me to Dave Dean, a metalworker and business owner of Flashing's Inc. We discussed issues related to the fabrication of metal greenhouses, and realized we had a friend in common: Ron Carswell!
    • Brad Castalia stopped by to see the arch and take Michael to lunch. It is great to be reacquainted after a 30 year gap without contact.
    • Michael reciprocated Chris Wendell's help with digging out the arch by digging planting holes for fruit trees on Chris and Wendy's property. Chris is growing vegies with a Peruvian-inspired keyhole garden design

  • Neighbor Leah Corbett thinned her aquaculture beds containing brussell sprouts and cabbages. Michael gave them a toasty home in the sheet mulch both inside and outside the arch. They appear to be surviving the transplant.
  • Native Seeds/Search Executive Director Bill McDorman recently returned from Greece, where he shared with Michael his observation of the common use of grape plants to provide shade on trellis supports for other plants grown in pots below. He reported he thought of the Nurse Tree Arch project when he saw this use of grapes.
  • Valdis and Silvija Krebs hosted a meet-up of organizational network analysis consultants in Cleveland this past month. Michael flew to Cleveland for the two day meeting. As the owner of NetOrganizing Consulting, one of Michael's intentions is to use public records to map the growing network of alternative agriculturists and food resilience activists and organizations. The software that Valdis created is called InFlow - and it is perfect for conducting research of this sort.
  • As the network of connections grows, the possibility of coordination and productive change in land use and water use policy regarding urban and rural small scale horticulture and agriculture improves. Given what we are up against (Monsanto-style global corporate agriculture), the need for close cooperation and reciprocity among those in the small-scale food production sector can't be overlooked. Kudos to the Watershed Management Group for progress on water policy at the city and county level. 

Above: ground sensor used for both T5 (see chart below) and T6; the T3 Sensor beneath the tomato canopy; the T1 sensor at the hot air intake; The T2 sensor in the cold air return.

The T3 sensor is six inches above the bed, under a four foot tall canopy of tomato plants. It reads 90.3 degrees. At 37 inches above the bed, sensor T1 reads 103.5 degrees, with a humidity of 13.1 percent.

The T2 sensor is reading the cool air return from the subterranean cooling system. That air is cooled 23 degrees - from 103 down to 79.7! The cool air is also laden with moisture: 44.9 percent.

Paul Reese provided me with these graphs of ground temperature and moisture Sensor T5 inside the arch, and T6 in a bed outside the arch in April 2013, the first month of sensor operation.

2) Produce from the Arch and garden beds provide a steady flow of vegies (even blackberries!):

What happened on June 28th to make the arch a less favorable place for the plants? The sensors tell the tale. In the charts below, Sensor T3 is marked by the green line in the charts below. By June 28, it shows temperatures beneath the canopy have risen nearly 10 degrees with the disappearance of the transpiration and shade provided by the cucumber leaves. Sensor T1 (in blue) shows air temperatures being piped underground from a point three feet off the ground inside the arch. Sensor T4 (purple)  shows air temperatures 3 feet off the ground outside the arch. Sensor T2 (red) shows the temperature of air coming from the plenum that returns the air after it has traveled through 36 feet of perforated pipe three feet below the ground in a gravel bed where temperatures are more constant: about 80 degrees in the summer. 

NOVEMBER 6, 2013


Spider mites first attacked bean plants inside the arch in early June. Stricken bean plants were removed. When the spider mites attack culminated with the destruction of cucumber plants overnight June 27th and 28th, much of the damaged cucumber occupying the south wall had to be removed. As a result, temperatures jumped at  Sensor T3 in the north bed, underneath the canopy of tomatoes. The green line in the chart below shows the impact - a big dip in the line - at around 17:00 (5 PM). This was cooling caused by spraying water to remove mites. Afterwards, the green line and the blue line (Sensor T1) become the same, because a significant cooling mass of leaves was removed. This loss of cooling effect just above the bed continues in the days after the spider mite attack. In order to deal with the increased heating, additional spraying and misting is required. Fortunately, monsoon rains arrived around July 4th, and the high temperatures experienced in June fell to more tolerable levels. 

August 16, 2013 Report:

Fabricating the Third Arch-a Temperature Controlled Raised Bed in a Nurse Tree

Tucson soils make a gardener cry ouch! That's the cry of frustrated hands on a shovel that hits caliche - the rock-like bane of a garden's existance. Water ponds on it. Roots are repulsed. If you want to garden, but aren't prepared to dig out the caliche, your options are four: Raised Beds, Aquaculture, Hydroponics or Container gardening.

All of these options have one big problem: They will get too hot or too cold in extreme climates.

The Third Arch prototype will apply the Arch structure and Subterranean Heating and Cooling System (SHCS)  to the problem of heating and cooling raised beds. 

If you want to follow the progress of this Third Arch Build, follow us at Facebook, or on Twitter

July 13, 2013 Report:

Cistern Raising and Spider Mites at 114 Degrees!

One of the major systems in the Nurse Tree Arch Project involves supplementing City water with Rain water. The best site for the 1320 gallon plastic tank also happens to be the tightest spot to put one. The tank is six feet ten inches wide and over six feet tall. Getting it into place required raising it onto the roof of our 1940's cement block storage building (now converted into an artist studio) and lowering it on the southern side where it can be rolled into place. Fortunately I've got some great friends who offered to help: Tim, Joel and Dan! Take a look at the movie to see how it was done.


The featured story by Tony Davis in the Business section of the Arizona Daily Star on Sunday, June 2nd is titled: 


March 16th, 2013

Open Arch Celebration Spurs Invention

A visionary project is accomplished in hundreds of small initiatives and actions - each an important footstep toward a dream. The Open Arch celebration on March 16th produced more advances - and brought together a diverse group of supporters. 

Fifteen people enjoyed a sunny Tucson day exploring the Nurse Tree Arch and the garden it sits in. Rosamond Finley, a member of the business development group that has helped shape the business strategy for the arch, was the first to arrive. Later in the day Bill Roach and Scott Rosenbaum of the business development group also came to celebrate and share thoughts about what it takes to get a new product off the ground. Gene Zonge of the Tucson Community Gardens organization came to see what was happening, as did Spencer Gorin, Dan Meyer and Tim Wernette and Carolyn Brown - all long-time friends and supporters of the arch. The arch project was blessed with the insights and interest of Tres English, Ron Proctor and his wife Nancy, who represent some of the most activist members of the growing sustainability movement in the southwest desert. Music therapist in training - Daniella Zormeier and her mom stopped by, as did Luke Ralston.  Chris Wendel provided delicious tangerine rind cookies. My neighbor Mery whipped up a delicious strawberry cake! Many more supporters sent regrets that competing commitments or geographic distance kept them from attending. The arch is always open - just get in touch with me when you have time to come by!

Michael is getting the software he needs to analyze thousands of data points, and with Paul is working to alter the programming of the Arduino so that reports are easier to construct. Over the summer we will refine our data gathering so that we can tell the world what difference an arch will make employing  subterranean heating and cooling, removable panels, and rain water misting to offset the damaging effects of extreme weather events and increased warming of the earth in which we plant, germinate and harvest our food.

June 2nd progress report 

1) The Nurse Tree Garden workshop is prepped for the "under roof - out of the sun" construction of the Scott Rosenbaum Nurse Tree "Screen-to-Greenhouse." The framing pictured below will help store materials out of the heat, and be wired for electric to support the saws and other power tools. The materials budget is funded and procurement of materials has begun. Expect photos and an update in July.  

Tucson temperatures in the month of June, 2013 set or matched records: 30 straight days of 100 degree or higher temperatures. In the Nurse Tree Arch the Arduino microcontroller logged sensor readings of air temperatures, air humidity, soil temperature and soil moisture levels. Remarkably, the arch kept its cool - consistently reading 15 to 20 degrees cooler at Sensor T3 six inches above the bed-under the canopy of leaves inside the arch. Cucumbers and tomatoes were growing in height and producing great fruit! Transpiration off their leaves helped cool the arch. However, on June 28th the arch got a fever!

January 26, 2013

The Nursetree Arch Prototype is Operational!


On Tuesday, January 15th, Tucson's low temperature was 17 degrees. That ranked as the coldest temperature in 38 years (since 12/24/1974). One week later we had record breaking 80 degree weather. Today we came close to breaking a record for most rainfall on this date. In the midst of all this difficult weather I am please to announce that the prototype arch is operational. Last night, in advance of a forecast for heavy rain, I labored into the night to fill peat trays with seeds purchased from Native Seeds/Search, a renowned regional seed bank based in Tucson. I placed twenty varieties of seeds in my lower terrace bed, under an arch opened to the sky. The attached video shows you the arch this morning as I went to check on the seeds.

March 2nd, 2013


February 20th was another surreal day in the desert. At mid-day a storm front arrived and it began snowing! 

It's rare for snow to fall in the lowlands beneath the Santa Catalina mountains, but nearly two inches fell. Temperature for the following four days stayed in the low fifties during the day and at or near freezing at night. This too is rare. Usually a front blows over and temperatures rebound quickly, but not this winter. February temperatures were four degrees below average due to these extended periods of cold.

Inside the Nursetree Arch it was a different story. On the snow day with thick cloud cover at 3:23 PM it was 54 degrees F. inside the arch and 41 degrees outside, with no additional source of heat! Squash, tomato and onion seeds planted February 13th germinated on February 25th, just as a third vortex of cold air arrived. This germination process was likely aided by the addition the night of February 24th of an oil space heater, set on low. At 6:20 AM on the 25th the outside temperature was 32 degrees while inside the arch, with the supplemental heat, the temperature was 40 degrees. 

Remove a few panels and you reveal an aluminum mesh that reflects heat back into space. Window panels turn into rain-catchers. Below the roots of the plants is a 3 foot deep bed of gravel cooled by a forced air system that circulates air through perforated landscape drainage tubes to bring the humid air to dew point: cooling the bed in the summer, and helping to heat it in the winter. The prototype structure that led to this approach kept it's ground-level garden bed temperature below 83 degrees during 114 degree summer heat.

A raised-bed prototype is ready to be assembled on the southern face of a hillside located in the Tucson Mountains on November 16th. Once it has plants in place, a set of sensors and a data logger will capture its performance. Homeowner Scott Rosenbaum is excited. He wants to be able to cultivate a garden, but his site lacks soil and protection, from javelina (wild peccary) as well as the unrelenting sun. All of this is the result of a Kickstarter-funded project called "The Nurse Tree Arch."

The inventor and project manager is Michael Ray. He is a Tucson native with a Ph.D in Higher Education Organization and Administration. Why has he embarked on a second career in urban agriculture?

  • "I'm a frustrated gardener on a low budget! The purpose of this project is to explore sustainable methods for nurturing and protecting garden vegetables in extreme conditions. My experience as a desert gardener led me to invent a kind of controlled environment that works with natural forces like transpiration and evaporation to reduce the need for energy in the form of electricity and potable water. I combined elements of a screen-house with elements of a greenhouse.  The arch served as an inspiration. It mimics the form of nurse trees like the Mesquite, whose shade and protective branch structure create a micro-climate where saguaro cacti and other plants can germinate and grow."

Michael is mentored by Biz Pathway expert Bill Roach. Bill provides low cost business start-up seminars which stress the importance of  prototyping as a way to long-term success. It was through Bill that Michael met his investor Scott, as well as other talented small business people who are helping him with the business side of the research enterprise.

The arch-raising, a combination group workshop and celebration of the structure, will be documented by videographer Kathleen Reeve, who is also a Biz Pathway student who is helping start-ups document their pitch for use on crowd-funding websites.

Gardener’s and non-gardeners alike have been getting a chance to see a display version of the arch at a variety of gardening and environmental festivals the past nine months. Michael notes that this exposure has provided the project with a rich source of feedback on people's experience with gardening in the desert.

  • "Gardening is something that people view as potentially a more secure food source, except that our environment throws a host of challenges at the gardener: sandy soils, low humidity in the spring, drying winds, and ninety degree days that can appear within two weeks of the last freeze. Sometimes it seems that spring doesn't stay around long enough for seedlings to really establish themselves. Add insect and animal pests to the picture and the interest in a more controlled form of gardening is a growing trend."

The micro-climate produced in the arch was successful this summer, with heirloom tomato, bell pepper, chili pepper, cucumber, carrot, bean and peas thriving in the first round of tests (see photo at right above).

The project is documented with a blog at Project Manager Michael Ray can be reached at

Bell pepper, Punta Banda and Nichols Heirloom tomato, Hatch Chili grow inside 

Snow falling at the Nursetree site in Tucson, Arizona February 20, 2013

October 30, 2013 Report:

Garden Sustenance in Extremely Dry Conditions

The summer monsoon winds blew in on July 2nd with .16 inch of rain, and as always, our hopes were high with the thought of summer thunderstorms. It is possible in one storm to get over an inch of rain in less than half an hour. Those hopes were dashed in the dust of our ongoing drought: a total of 2.04 inches of rain fell on the Nurse Tree Garden in the months of July, August and September. The last significant rain, a total of .24 inches, fell on September 10th. Below is a copy of the Water Year Summary for our site. It is easy to see how far short our totals (the blue bars) fell relative the 30 year average (the blue line).



A Project of Nurse Tree Arch Design, L3C LLC - funded through Kickstarter and Indiegogo - Contact: Michael Ray -  - (520) 609-3653

Trees Suffer in the Drought

At nine in the evening of October 21st we heard a crash outside the house. A twenty foot, 100 pound limb from the eucalyptus tree fell thirty feet, nearly damaging the display arch which was stored waiting to be reassembled after showing at the "Envisioning Tucson Sustainable Festival" held Sunday, October 20. This was one of ten large limbs this tree has shed in the grips of the drought. Our big trees did not get a deep watering from soaking rains this summer. The result is loss of limbs, and in some cases, loss of an entire tree. 


3) The design for a custom built screen to green house for a Tucson foothills home has come through it’s first review by the client. It will be built into a southeast facing corner and feature panel storage and raised beds.

4) The Arduino microcontroller is working after fixing a bug in the programming – overheating is not the problem. I’m soon going to pull the data from the S-chip and take a look at the data on soil and air temps for the month of March and April. Stay tuned for report in the near future.

5) Inside the arch and outside on mounds and in sheet mulched basin beds beneath the Palo Verdes, , Acacia, Hackberries and Mesquites we support a thriving community of native and heirloom squashes, beans, lettuces, onions, melons and tomatoes. We are harvesting Scottsdale and Tom Thumb bibb lettuce, Bloomsdale spinach, Suger Ann snap peas, Kinko ad Chantenay carrots, Kentucky Blue beans, white sweet Spanish onions, and Crookneck and Dark Star Zucchini squash. Tomatoes are blossoming. If you are in or near Tucson, please arrange to visit us and see the wonder of it – all germinated in the arch in January and February and April. 


April 25th, 2013

Earth Day-Gratifying Results

Five hours, over one hundred brochures and surveys distributed, and over forty seedlings in new homes: that was part of the Nurse Tree Arch experience at the Tucson Earth Day Festival. 


1) The "kit" pre-fabricated elements of the compact arch went up without a hitch. As we built it the admiring comments began coming from those vendors and early attendees in the area. The glint of the Aluminet shade cloth caught many an eye. As the day got hot (90 degrees) many sought shelter in the 70% shade, and were surprised at how comfortable life was beneath the arch!
2) We have some highly interested potential clients in the education world. Many schools have gardening programs, associated with an environmental science curriculum. The arch excited the imagination of many educators at the festival, and we have some serious leads as a result.
3) Twenty-nine surveys were completed, which gives us a much needed perspective from gardeners who had a chance to look at the arch in terms of their own gardening needs. Much thanks is due to Acacia Alder, who helped staff the display and made it her mission to get people signed up on our registry.
4) Over-all, the response from people validated the development of the arch. People expressed appreciation for it's beauty, its functionality, and its larger purpose.


  • NURSE TREE ARCH IS PARTNERING with a private individual to build a modular (cubicle) structure using the removable panel technology found in the arch. Design work has begun, and more information will be published as we get close to installation.
  • THE MIST KING MISTING SYSTEM HAS ARRIVED! Soon it will be installed-just in time for our hot desert weather. The 50% shade cloth in the prototype will be swapped out for 70%. We will experiment with misting to cool the Arch open (screen mode) with Aluminet, and with the arch closed (greenhouse mode) with Aluminet inside the Solexx panels. 
The Display Arch (aka the Space Saver Patio Arch) will make it's third appearance this year at the Envision Tucson Sustainable Festival, Sunday, October 20, 2013, 10 am to 4 pm in Reid Park at the DeMeester Outdoor Bandshell.

Since it's debut at the Earth Day festival in April, the display arch has gotten an upgrade with new banner and display material! Thanks to Doug and Leah at the Arizona House of Graphics for the quick turnaround on my order. If you are interested in volunteering to help assemble/disassemble the display arch or hand out brochures, let Michael know. We met some dedicated gardeners at the Organic Garden Club's fair - 15 of whom signed up for email reports. Thanks to Javier Lopez for help setting up, Acacia Alder for lunch and help staffing, Carol Maun - Special Events Coordinator, for her invitation and support and the club volunteers who folded our handouts! This is a great opportunity to network with gardeners. Many expressed concern about the impact of a changing climate, and looked at the Nurse Tree Arch as a vision of what we can do to adapt gardening to weather extremes. As usual, the Aluminet shade cloth and Solexx glazing got attention, as did the arch itself.

The Nurse Tree Arch in raincatcher mode 

"At nature's mercy - Farmer's struggle to cope as weather gets more wild and extreme, damaging winter crops and putting their livelihoods at risk. "Some farmers say extreme weather events seem to be more frequent in Southern Arizona, forcing them to adapt."

The article goes on to report on the experiences of Southern Arizona farmers from Cascabel to Yuma.

The Nurse Tree Arch project is a manifestation of the concerns voiced by the farmers, and increasingly voiced by food resilience activists and urban gardeners as well. There is definitely a social movement awakening here in the desert southwest, and beyond. Growing food is a survival issue and directly impacted by climate. Adaptation and innovation are essential ingredients in our response, along with raising awareness and changing the political will to face the challenges that are now at our doorstep. Not the least of these is our use of water and energy. 

Another innovation is the use of Aluminet shade cloth, which reflects some of the sunlight back into space, and demonstrated its ability to lower temperatures inside the arch ten degrees on the day it arrived, March 2nd, when temperatures outside soared into the 80's. Then temperatures dove into the 40's again with more snow on the mountain on March 8th, followed by the aforementioned 90 degree heat. A week before the celebration Paul delivered the Arduino unit, and I hurried to get the electrical installed to support it. I placed it midway up the North side wall, and in the first day of operation there was a problem with overheating inside the sealed box. In conversation with one of the guests at the "Open Arch" a solution was proposed - put it in the coolest place in the arch: the ground. That is where I put it today, and tomorrow I will see if it helps the unit to function.

I hope you get a sense of what this process of innovation involves - constant tinkering, feedback from visitors, suggested changes, challenging weather, self-imposed deadlines, and fixes on the fly.

The Arduino and sensor wires in a cool vault - six inches into the bed, with a redwood frame and a cover to keep the sun out.

In the weeks before the celebration, I had to think "be careful what challenges you wish for." The challenge of extreme climate is one of chaotic temperature and weather extremes, and this February and March has illustrated the gardening dilemma: it is getting warmer sooner, but the amount of daylight stays the same: thus it can be said that February is the new "spring" but that doesn't mean there is a long enough day for much growth to occur!

Seeds were sown January 25th, began germinating February 5th, and were being transplanted into outside (and inside arch) garden beds by February 23rd. On February 20th it snowed in the desert, a somewhat rare thing to see. A week later, on March 2nd, temperatures hit the 80's.  By March 14th, two days before the Open Arch celebration, record heat in the 90's arrived. I am happy to report that the arch has functioned remarkably well as a mime of a nurse tree should. Healthy plants are growing ever more rapidly as we approach the equinox. I'm particularly interested in how the Hugelkultur beds will work for the squash and beans. At this point they are all beginning to grow rapidly. The mounds really do function as big sponges. Set a hose on one and it doesn't run off, it just disappears into the interior wood pile, a magnet for roots.

I displayed a line graph at the open arch showing many of the operations involved in opening and closing the arch panels as the days warm or cool - to moderate the impact of the temperature swings, sometimes as much as 40-50 degrees in the space of a week. The panels are light enough to move easily, and I have innovated with the creation of a moveable bench that slides over the inside bed, to make managing the panels easier, while also providing a platform for tending the plants in the tight space. Here is what it looks like:

Arduino controller (center) with sensors (left) and power supply (Right).

The cucumber plants June 10th

Aluminet shade cloth draped over the arch on a 80 degree March day.

Adaptation to extremes of heat and cold is a central factor in the development of the Nursetree Arch.

For those of you who live in wetter climates, the screen to greenhouse may seem unnecessary, and for a pastoral activity like backyard gardening, a bit dramatic. Why not just spend a bit for a heating and cooling system for a regular greenhouse, throw some shade cloth over a hoop structure, and get on with gardening?

Adaptation to a natural world that is undergoing dramatic change is driving this drama, and it has at it’s heart a once virtuous relationship between electric power and water. The more 100 plus degree days, the more likely people are to seek air conditioning, and in the garden, the faster the pace of evaporation. The more people turning on the AC, the more likely a vulnerable electric grid impacted by diminished hydroelectric capacity, or failures due to forest fires will not be able to respond to demand. Brownouts and blackouts become a greater probability, and the pumps that bring the water to agriculture and cities require electricity. The more coal-powered electric plants built, the more CO2 and climate warming.  In my desert city backyard, the once virtuous relationship is becoming a sobering reality. At the recent Earth Day Festival I talked to people about the arch. They made it clear-the confidence needed to grow food in this sandy loam soil (which has always been a challenge in the desert) is now appearing to be constrained to at best, a late fall, winter and early spring activity as the number of 100 plus degree days (F.) grows and grows.  Very few people, and fewer plants enjoy the reality of water evaporation and stunted plant growth in the extreme heat. Many of us do not have the budget for heating and cooling a standard greenhouse.

The recently published draft National Climate Assessment measures the extreme climate context for this Nurse Tree Arch: an invention powered by necessity on our doorstep.

The draft assessment of the impacts of climate change on the U.S. has been released by the Global Change Research Program in Washington, D.C., and is available online for public comment, here:

For Chapter 20 on the Southwest, the introduction provides a quick take on what's at stake:

The Southwest is the hottest and driest region in the U.S., where the availability of water has defined its landscapes, history of human settlement, and modern economy. Climate changes pose challenges for an already parched region that is expected to get hotter and, in the southern half, significantly drier. Increased heat and changes to rain and snowpack will send ripple effects throughout the region’s critical agriculture sector, affecting the lives and economies of 56 million people–a population that is expected to increase by 38 million by 2050. Severe and sustained drought will stress water sources already over-utilized in many areas, forcing increasing competition among farmers, urban dwellers, and the region’s varied plant and animal life for the region’s most precious resource.

Here is the May 4th, 2013 progress report:

1) The misting system is installed in the arch and undergoing testing. It is a Mist King system with three misting nozzles supplied by a ten gallon tank in the ground where the doorway pavers used to take up the limited real estate. A major concern is the certainty that if I use potable water, it’s mineral content will soon create calcium plugs in the fine mist openings of the nozzles. The manufacturer recommends reverse osmosis, de-ionized water, which is a buck a gallon at Walmart, and results in ten empty plastic gallon containers to recycle with every fill-up. The good news: a three minute misting session will take the temperature down from 95 F. to 79 F.  How many 3 minute misting sessions will 10 gallons support? How long does it take for the heat to return after a misting session? Can the pump be powered by solar electric panels? Will harvested rainwater prove to be a workable alternative? That is what I will be finding out. Next week I will be learning the art of building ferrocement tanks at a workshop presented by the Watershed Management Group. The  next big project? You guessed it! A ferrocement rainwater tank for the arch-hopefully in time for the summer rains!

Inside the arch, The T5 sensor reads a temperature in the bed that is 80.6 degrees. The sensor is calibrated with its companion T6 outside to give a percentage of moisture in the soil. Both read 85.1 percent. Our sheet mulch is performing well in both spots!  

Above: Photos of the Arduino microcontroller readout screen for six sensors from which it is logging data. The middle photo shows the T4 sensor outside the arch, with newly installed aluminet screen protecting beets and lettuce in the bed. The T6 soil temp sensor is out of view at the base of sensor array.

​Squash planted on mounds in the direct sun are wilting. Underneath the canopy of Mesquite and Palo Verde, no wilting is detected. 

Under the Shade of the Nurse Tree Arch - A Reason to Think We are On to Something

Open the door to the arch, and be greeted by sweet red bell peppers, savory hot Hatch chili peppers and tomatoes that are continuing to grow and produce. Social media maven Pamela Morse (aka "The Spa Lady") takes a look from inside the arch. This is what garden sustenance (aka "sustainability") looks like in my backyard.

Meanwhile, Scott and Edna were in the garden to look at their nearly completed "raised bed arch." 

It is 90% complete. Stay tuned for an announcement about an "arch raising" party in the near future. If you want to be informed, send your email address to Michael Ray at

April 19, 2013

On the Way to Earth Day!

The prototyping process continues with the construction of the second arch - the Compact Display Arch. 

On Sunday, April 21st at 8 am, an arch will be constructed on the grass at the Reid Park Demeester Outdoor stage exhibitor area. This Nursetree arch is ten feet across and six feet deep. The construction incorporates all the learning from the first prototype and is built in modules that will fit in the bed of a small truck. It is a shade arch, with Aluminet shade screen, as well as some Solexx glazing panels at the base. Seedlings grown in the original prototype arch will be offered along with a survey on the Managing the Impact of Extreme Climate on Gardening Success. A hands-on activity for children will help them make their own newspaper pots. This is the first public display of the Nursetree arch - a milestone event in its development. The event opens to the public at 9 am and closes at 2 pm. Come join Michael and Acacia in celebrating this public outreach on Managing the Impacts of Extreme Climate on Gardening Success!


1) January 7th the Arch welcomed nine Elon University students on a winter travel course exploring Eco-Futurism in the vision of Paulo Soleri's Arcosanti, Frank Lloyd Wright's Taliesin West in Scottsdale, and the Biosphere 2 outside of Tucson. Backer Meredith Emmett hooked me up with Anthony Weston, author of Mobilizing the Green Imagination, and he brought the students to see the Nursetree Arch. In a 3 hour workshop, we screened and returned escavated fill to the basin with its plenums and tubing installed. We brainstormed about how to better get the rain-catcher wings to work (you will see a new approach side-by-side with the original wing in the video).  I was thrilled to visit the Biosphere 2 with the group, and to have them as my guests! See the group photo in the next column.

2) January 16th I attended a panel discussion on urban agriculture where I listened to Bill McDorman, Executive Director of Native Seeds/Search (mentioned above). I've asked Bill to consider meet with me to discuss the possibilities of a partnership to explore the performance of the seeds in the arch environment, and to work on finding early adopters for the arch.

3) At that same panel discussion I met Jeff Silvertooth, Associate Dean of Agriculture at the University of Arizona. He responded to my questions about a change in the heat cycle of the planet's soil with information about a monitoring program the University hosts called AZMET. There I found a wealth of data on soil temperatures and plant preferences for what are called Heat Units. This metric is what seed packets use to tell you when to schedule vegetable plantings, predict harvest dates and manage crops. It also opened up a conversation to me about concerns regarding the viability of major cash crops like corn, and questions about how much more heating they can tolerate.

4) January 20th I presented the Nursetree Arch project to a general meeting of the residents of Stone Curves Co-Housing Community, who coincidentally are just a stones-throw (literally) from my own house just across an intersection. I got the attention of their "green team" initially when I was scouting a site for a second arch to be constructed with a grant from the community food bank. Their interest was not fazed when the grant didn't fund our project, and about ten of the community at the presentation came over to see the Arch in person. Their excitement helped me renew my own after a week of heavy lifting refilling the basin.

5) January 23rd I heard from Paul Reese, my Arduino micro-controller team-mate, with news that the sensors are working, and that the outlets to control the fan are wired. Paul has some coding work to do, and I should have the controller soon. Thank you Paul!

6) Today I attended a city wide meeting of neighborhood leaders to listen and learn from each other's experience. I spoke with Ron Proctor, who is also a member of Sustainable Tucson. I may get a chance to share my Kickstarter project experience at a meeting they sponsor. More importantly, Ron offered to help me find early adopters. That is the kind of response that really helps me keep putting one foot in front of the other. 

NOVEMBER 17, 2013


The Sonoran Desert has something in common with the Earth's polar regions: rising temperatures take us into new and perverse conditions. In the north polar sea, the ice is melting, allowing ships unfettered passage. In the desert, already dry and hot, the heat expands its grip into spring and fall seasons, making growing food an even greater challenge for farmers and backyard gardeners.  

On Saturday, November 16th, 2013 the first production model of the Raised Bed Nurse Tree Arch was taken apart at the workshop site in Tucson, moved to the site on a saguaro-studded hill outside of town, and assembled by a group of ten volunteers: Michael, Scott, Edna, Gary, Bill, Javier, Acacia, Kathleen, Joanie, and Rob. Having a community of friends "raise" the arch was an exciting experience. Together we proved that such a kit could be broken down into over a hundred parts, and then reconstructed on site. The puzzle pieces (with the exception of one window module), all fit together like they should.

Below are photos of the asssembling of this third prototype "kit" - an arch that holds within it an insulated raised bed with a forced-air heating and cooling system in a gravel thermal mass. Steel siding and solex glazing will help protect plants inside from critters outside and the rapidly changing weather conditions.

In the days to come the beds will be filled with gravel, soil and compost. Installation of double Dutch doors and polycarbonate skylights will be completed. Aluminet shade cloth will be cut and prepped for use when the next eighty degree days come. Come December, the owners Scott and Edna will be gardening with an eye on germinating seeds for that early Spring and long summer. More data will be collected on growing bed temperatures, and you will see the results on this website/blog.

Over the months ahead, Michael will be looking at subcontracting truss and panel fabrication, and working on the next series of prototype arches. A bermed arch structure housing an aquaponics system is possible, as is an teaching arch for a local school (possibly several schools)! There will be another round of fundraising in the new year. Keep your eyes on this site for next developments as the Nurse Tree Arch project finds a path toward producing many more arches, and developing a new mode of gardening in the southwest deserts and beyond.

3-2-13 Project Updates:

1) SAVE THIS DATE: March 16th, 2013 from 10 AM to 5 PM is an opportunity for anyone interested in learning more about the Nursetree Arch project to drop in and take a look. There will be refreshments and exhibits of the arch building process, as well as the operational arch itself to see. The backyard garden at this Limberlost property is also a delight, and it will  be early Spring in the garden. Contact Michael to RSVP.

2) February 9th through the 11th Acacia and I hosted Linda Stout for a visit to the arch. Linda is both a friend and Nursetree Arch Kickstarter backer. She is also a great business coach and the organizer of a wonderful project that brings African women to the U.S.A. for leadership training regarding agriculture. This program is called "Service Learning for Women" and is sponsored by New Mexico State University. Linda and I explored the concept of social entrepreneurship in our time together. Thank you Linda for your investment of time and generation of supportive ideas!

Paul Reese shipped the complete Arduino Micro-controller and sensor unit and it arrived several days ago. Over the phone we will load software, set the timeclock and I will complete installation of the electrical and the panel with all this wonderful computing power. Soon my laborious data entry of sensor temps will be over and the Arduino will be logging temps and humidity of soil and air every ten seconds. This is a huge step for the research side of this endeavor, and I am looking forward to seeing Paul, Leslie, Lorrie and Tommy and my grandkids in time for Easter! Paul and I will explore adding additional functions like control of fans, and a water valve. 

3) Networking and engagement in the larger issue of adaptation to climate change:

  • Michael is a member of the Neighborhoods and Vulnerable Communities Working Group - a subset of the Climate Smart Southwest - Ready of Hot? Conference hosted by Physicians for Social Responsibility, September 20-22nd, 2013 at the Tucson Community Center.
  • Michael participates in monthly meetings of "Sustainable Tucson" - a local focal point for citizens and activists working for sustainability in the face of social, ecological, and economic disruptions.
  • Michael joined seven other Watershed Management Group workshop participants in the construction of a ferrocement cistern. The last part of the research framework for the Nurse Tree Arch is the collection and use of rainwater for growing plants. With the help of a City of Tucson rebate program, the Nurse Tree Arch project hopes to install a cistern near the arch this summer. Will it be a ferrocement tank or a plastic tank? Michael is talking to workshop leader Mark Ragel and hopes to confirm plans soon.

June 2nd, 2013 Report:

Nurse Tree Arch and Garden at 106 Degrees in the Shade! 

The big challenge to desert gardeners is Summer heat and evaporation. Below are some photos documenting heat stress at 3 PM on June 2nd, 2013 in the Tucson, Arizona Nurse Tree Garden and Arch. The temperature in the shade is 106 degrees Fahrenheit. The T4 sensor 3 feet above the ground outside the arch reads 113.4 degrees - an aberration caused by the addition of Aluminet shade screen to protect the exposed bed (and the T6 soil temp and moisture sensor) just underneath the T4 sensor. That outside sensor indicates an atmospheric relative humidity of 11 percent.  

October 15, 2013 Report:

Glazing Completed on Third Prototype/Built-In Raised Beds with Forced Air Cooling is Under Construction/The Arch is on Display - October 12 at the Organic Garden Clubs Fall Fair, and Sunday, October 20 at the Sustainable Tucson Festival. 

Temperatures in the 80's are helping the arch gardener to bring the third prototype to fruition with a bit less sweat and salty tears.

Building the first version of the raised bed arch has its highs and lows. The highs are associated with realizing a solution to a design problem when you wake up in the morning. The lows are mostly about the perseverance through failed attempts needed to realize the dream. Within the next ten days the latest prototype arch will be completed at the Limberlost workspace and then dismantled and trucked to its home in the Tucson Mountain foothills.  The process will be documented and this blog updated to reveal the first Nurse Tree Arch in a Foothills location. 

2) The compact display arch is now located next to the prototype.  It is inspiring another batch of innovations – like compact raised beds that fit into the modular nature of the arch.

4) With high heat on it's way, I ordered Aluminet reflective shade cloth for the arch. It arrived as I am writing, and the picture below shows it draped over the arch. I will build additional panels with Aluminet that will swap out the Solexx greenhouse panels that currently contain the heat. "Greenhouse to Screenhouse" is going to happen sooner than later (temps today are expected to hit the 80's, and at 12:45 PM it is 71 degrees outside and 99 degrees in the unvented arch. After moving the top four roof panels into the vent position, the temperature inside the arch fell five degrees in five minutes. An hour later the outside temperature is seven degrees hotter at 78 degrees. After draping the Aluminet over the arch the temperature inside fell from 96 to 92 degrees. 


1) Install the electrical system, the Arduino controller, and sensors. Begin logging data by first week in February. (In progress)

2) Complete detailing of the arch, and develop new watercatcher wing approach, by mid-February. (Completed)

3) Revisit and update the business plan with feedback from the construction and visitor observations by mid-February. (In progress)

4) Prepare for presentations at Earthday and beyond. Update the portable display model of the arch, by early March. (In progress)

5) Draft a marketing and financial plan to add rainwater harvesting, and to support building a second arch utilzing berms for heat exchange, reducing the need to dig as deeply for the subterranean heating and cooling system. Complete by mid-March (In progress)

6) Plan and implement a celebration and open house to introduce the Nursetree Arch to the community, mid-March. (In progress)

Seedlings inside the Nursetree Arch, thriving in high humidity and tropical temperatures