I’ve kept records of rainfall since 2011. That was when I joined the Community Collaborative Rain, Hail and Snow (CoCoRaHS) network. CoCoRaHS is a unique, non-profit, community-based network of volunteers of all ages and backgrounds working together to measure and map precipitation. The premise is simple. When you join the network you purchase a rain gauge that is standard for the network ($48) at the Weather My Way online supplier. When you join you get an unique identifying numberfor your site. Each morning you check the gauge. Then you login to the CoCoRaHS website and enter the amount in a precipitation report. You can then view a map of all the other observers reporting rainfall in your area and entries from all the other volunteers in the network. You also get a water year report showing when you got rain (or hail or snow) and how much you reported on a specific date. This report also gives you the twenty year average for precipitation at your location. This connects you to a national data base supported by over 15,000 observers. It’s a great way to support citizen involvement in meteorology science.

In 2020 the National Weather Service recorded 4.17 inches for the year, the driest on record. It eclipsed the former record of 5.07 inches in 1924. Eleven miles north of the airport at my site I recorded 5.6 inches of rain for the year. The monsoon period (June -September) recorded only 1.67 inches for this period, granting it the moniker “the nonsoon.”

The contrast of 2020 with 2021 is stark. 2021 was the third wettest monsoon on record. The June to September total was 12.79 inches, a 7.10 inch departure from the normal monsoon rainfall of 5.69 inches. At my site precipitation was 11.27 inches. It is times like this that I could use three times the rainwater storage that I have now.

While I’m on the subject of meteorology, I was accepted as a speaker in the first ever American Meteorological Society Weather Band Symposium held on Zoom January 21-22, 2022. As a part of the process of designing the Nurse Tree Arch, I put together a 16 year picture of Tucson temperature ranges (reported at the airport) and rainfall reported from my CoCoRaHS gauge. In a narrated slide program I shared the resulting data about weather in an easy to understand picture of the temperature ranges. I explained that the weather picture helped me understand how to manage temperatures in my garden and the Earth Arch. You can find a small rendering of the temperature range graph below and the 15 minute slide program at YouTube: https://youtu.be/mLDp4VRd9N0

This brings me to the continual tests for the Nurse Tree Design. The five layers of protection provided by the Earth Arch are the Aluminet shade cloth, fast growing Pomegranite tree protecting the west side of the structure, hydrophobic row cover, polystyrene panels, fan and mulch. This combination allows me, the gardener, to customize the arch for the temperatures and weather extremes I encounter here in the Sonoran desert.

I’m harvesting tomato’s planted in March, 2021 in January, 2022. This is the result of getting sensitive tomato plants through the extreme heat and dryness of early summer, opening the arch to the third wettest monsoon on record, and then, as best I can, keeping the plants at a range of 50˚- 90˚ f. I do this by configuring the arch with a combination of Aluminet, row cover and fan through summer into the fall.

The data I collect comes from calibrated SensorPush HT1 Wireless Thermometer/Hygrometer cubes located inside and outside the arch ($50 each). The cubes are mounted inside La Crosse Technology 925-1418 Sensor Protection Shields with Mount ($19 each). In the middle photo is the CoCoRaHS rain guage available for $49 from Weather Your Way. On the right is the the Tempest Weather System from Weatherflow.

2021 Earth Arch Configured for Heat and Cold

The hottest day of 2021 was 116˚ on June 15. Ground temperatures outside the arch were in the 150˚range.

On June 15 the Earth Arch was configured with a 40% Aluminet cover, hydrophobic row cover curtains closed with venting at the top and the south side polystyrene windows open. The fan was on and pushing 86˚ f. air from inside the workshop into the arch. I

In contrast to the denser 75% weave I’ve used in the past this was an experiment with the more open 40% weave of Aluminet. The temperature inside the arch was 104.2 at 2:48 PM, 12˚ f. cooler than outside. Inside the soil was 80˚-85˚. The 75% kept the arch about 4˚ f. cooler than the 45% . Blossom drop was inevitable, but my purpose at this time of year is to keep roots, the microbial community and above ground tissue alive, so that I can get production in the fall and winter.

With temperatures in the 30˚ range this winter 2022 I supplement the arch with a small space heater to keep temperatures in the range needed to avoid blossom drop. On January 2nd the minimum reached 30.8˚ f. at 8:01 AM. Inside the Earth Arch with the heater assist, the temperature low was 39.9˚ f. The average temperature was 58˚inside compared with 50˚ f. outside. The temperature high inside the arch was 81.5˚at 2:27 PM. No blossom drop was observed.

12/24/20

Stressful Care of Limberlost Garden in High Duration Heat and a Pandemic

I built an arch shade house in March 2012 to help heat stressed squash survive fierce sunlight. That shade house got me thinking about the future of my garden. I could forecast problems already showing up under long-duration heat and drought. The arch shade structure seemed like it might be a good framework for experimenting with shade to control temperatures of the bed. I raised about $5000 in four rounds of crowdfunding using Kickstarter and Indiegogo platforms. I documented the creative process that produced ten arch variations that were part of a business development process using prototypes. Four of those prototypes were commissioned by supporters. The Earth Arch design took advantaged of insights gained from all of these experiments, as well as my own history with solar heated housing.

Summer of 2019 would put a different kind of stress on my forest garden and the Earth Arch (EA). It was time for Acacia and I to escape the summer heat. We planned a series of trips that would keep us out of the desert most of June, July and August. I employed a rotating triad of friends of friends to care for the food forest, the animals and the EA. The plants were dependent on hand watering, completed early in the morning. I was nervous about this plan, knowing much attention was needed. Its success was a roll of the dice.

The first week of June 2019 we got to see my granddaughter Hailey graduate high school in California. After that we flew to Seattle and got to spend two weeks with Bob and Donna of Rokalu farm on the Kitsap Peninsula. Bob and Donna host two young couples who lease land for organic gardens that feed the surrounding semi-rural population. Bob operates a thriving composting operation and drives a tractor that scares me half to death. It was great contrasting a small farm operation to my house garden.

The remainder of our 2019 July and August trip plans were upended by the health emergency of a family member. On our return to Tucson it was clear that our backups were not able to cover all that was needed. The garden made it through 3 weeks, but I had no solution for a several month absence. That experience led me to build a drip system that would lessen the stress of early morning waterings on housekeepers. Bob introduced me to hose-end water timers. I would bring that concept back to Tucson and spend a year implementing it, completing four zones in early July 2020. By March when the pandemic came along I completed two of four sectors of irrigation. Any plans for a summer get-away would soon be overwhelmed by the Covid-19 pandemic, and the one of the hottest summers on record. July 2020 was the hottest and 10th driest on record. On June 5, 2020 a lightning strike started the Bighorn Fire in the Catalina Mountains northwest of Tucson, Arizona on the Coronado National Forest. It would burn 119,978 acres, adding smoke and air quality concerns to the heat. It wouldn’t be 100% contained until July 23rd. This was followed my record all time heat in August, September and October. All told, 2020 was the 2nd warmest on record, setting a yearly record of 108 days of high temperatures 100˚ or hotter.

The Water Mystery

Late in June in order to complete the drip irrigation I hired a contractor to install the third and fourth sectors of my hose end water timer system. It was completed July 2nd. When my water meter was read on August 5th, I was sent a bill for $742. The property typically uses about 25 to 30 CCF in July. This bill showed 60 CCF. We used an additional 30 CCF (One CCF = 748 gallons) which is 22,440 gallons. Keep in mind that I and the world around me were reeling from the stay at home orders due to the Covid-19 pandemic. Arizona was one of the states with the widest spread of the virus. I did my best to keep a distance from the workers, fearing for my own health. The result was that I had no real idea how many emitters were installed. My first impulse was to check the four toilets on the property. None showed any sign of leaking. My next impulse was to think the installation of the drip system was the problem. Yet I couldn’t see any evidence that a swimming pool’s worth of water was leaking, I was stumped. To make a long story short, after reading my meter and ruling out my household use and drip systems, I went back to a toilet in the separate studio building that had practically no use during the summer. This time I scrutinized the studio toilet carefully. Again there was no sign of it leaking when I flushed. I flushed it twice and the chain got hung up. I flushed it again after resetting the chain and the source of the leak was revealed. The handle did not return to the full down position, leaving the float valve hanging. That is how you lose 22, 440 gallons in a month – 748 gallons a day, 31 gallons an hour, half a gallon a minute, for 30 days.

Scott and Edna’s Arch Gets Restored

Scott and Edna’s Arch was completed in 2013. Scott and Edna love this garden structure. It sits on a steel plate over a culvert that diverts the monsoon streams of rainwater from above their house down a steep desert mountain hillside facing south. This location gets plenty of solar radiation as well as canyon whipped winds. A few years after construction they installed a mist system to help cool the interior. This structure used the original prototype arch design built with 2’x4″ lumber using exterior plywood gussets sealed with acrylic primer paint. The gussets sustained severe water damage from the mist system. In November and December 2020 I’ve replaced every plywood gusset with steel plate gussets and aluminum sheeting to cover the space where the plywood once was. Quarter inch concrete board lining the raised beds lacked a backing of plywood, and as the soil became wet and expanded, cracked the board in multiple places. The expansion also pushed side-walls outwards, forcing corners to spread. Fixing this damage involved placing new concrete board over the old, and waterproofing. This experience illustrates the value of learning from a prototype. I’d never built a raised bed structure out of 36″ high side walls before. Now that I’ve been back to repair the structure, I’ve learned alot about how it should be built.

The Writing Challenge

I finished my last commissioned arch for Rod and Carol in March 2017. The Earth Arch, which was started in December 2014, wasn’t completed until April 2018. The amount of finish work (sanding, sealing, priming, painting) for over 200 components was simply overwhelming. In the end it was an endeavor I couldn’t manage by myself. So I assessed the situation, knowing I was not going to risk taking on debt to grow Nurse Tree Arch as a business. I decided that the best way forward was to document the learning from the Nurse Tree Arch project, in writing – perhaps as a book. There is a good story here to be told about the challenge of home gardens under conditions of high-duration heat and drought. It is reasonable to ask the question: how will we continue to support gardens when the cost of water becomes 25% more expensive. Already the quality of potable water is problematic, due to chlorine disinfectant and high mineral contents. Given that I am using rainwater as much as is available, the record drought conditions means that I ran out of rainwater in June, and as of December when I write, I’ve got no more rainwater stored than I had in June.

In spite of tough conditions, the Nurse Tree Design project reveals that we can control heat and water loss through managed applications of shade, humidity containing row covers and fans moving the air. The research results are finding their way into writing. Stay tuned for more reporting of results on this blog site in 2021.

Winter into Spring is a rite of passage for this desert gardener. Some of our kale is in its second year with long stalks. Kale planted in the fall of 2018 is maturing, providing a reliable source of greens for breakfast eggs. Our household is beginning to realize the vision of a reliable year round source of greens. On February 2nd, in advance of a cold front bringing rain, I planted lettuces, stir fry greens, arugula and purslane. On February 22nd we had that rare snow event, put the Solexx covers on the Earth Arch, drawing the high tunnel row cover closed. This kept temperatures ten degrees warmer for peppers and tomatoes on the following night of below freezing temperatures. Plants in the hugelkultur beds outside got covered with old bed sheets.  Late in February, with the help of my granddaughter Hannah, we assembled a balloon mapping kit from Public Lab, a community where you can learn how to investigate environmental concerns. I wanted to get a clear view of the food forest canopy, as well as the four arch structures on the property. This proved to be possible by launching at sunrise, when winds are light. By April, golden beets, kale and dill are filling in the hugelkultur bed. Tomatoes and overwintered bell peppers are producing fruit. The next challenge will be the onset of high heat in June through September. We were fortunate to have a mild May, due to the jet stream being forced south by the high pressure over the arctic. Of course, this meant Alaska was much warmer than normal, and the midwest and southern states suffered damaging rains and winds.

This will catch my readers up on continued work, most of which has revolved around completion of the desert adapted solar greenhouse that I call the Earth Arch. A solar greenhouse is defined by Lindsey Schiller in the Year-Round Solar Greenhouse as “a structure that works with local climate and resources, using the sun as the predominant energy source not only for growth but for the structures  energy needs.” In this case I use the massive earthen walls surrounding the raised beds to keep bed temperature at around 80 degrees throughout the hot summer, where ground temps outside the arch easily reach 150˚ F. Rather than collect solar energy, the arch helps reflect it back into space using Aluminet shade cloth, while slowing transpiration and evaporation by draping hydrophobic (water restraining) row cover beneath the shade. Solexx glazing used in the winter is removed, or put in an awning position for maximum ventilation. A fan moves AC cooled air from an adjacent room through the south wall and into the Earth Arch. Together the temperature inside the Earth Arch is 94˚ F. – reliably 14 or 15 degrees cooler inside compared to temps outside (108˚ F. ).  Though not complete, I have installed an additional Ground to Air Heat Transfer (GAHT) system in the ground on the east flank of the Earth Arch. I will get it completed later in the year

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“Oversummered” tomato plants ready for second harvest in the Earth Arch

The Early Girl tomato plants made it through one of the hottest summers yet, and have set a second crop of about 70 fruit in the hottest fall ever. A 122 year old record fell as well, along with witnessing the latest ever 90+ degree in November, recorded on November 27th. The combination of Solexx, Aluminet and hydrophobic row cover helped control the effects of sunburn, evaporation and transpiration in raised beds on a south facing wall. Preparations are being made to complete the Solexx arch cover and install framing on the southern opening – as colder weather is on the horizon.

Work on the Entry Arch for Rod and Carol began in October with a design review and client approvals. This second Entry Arch Prototype focused on sun and rain proofing the exterior grade plywood using boat builder techniques. We used Smiths expoxy sealer with multiple coats of primer and acrylic. Rod helped with the additional labor that this required, as well as time needed for curing. We suffered delays from illness, weather, and competing commitments. The fun part is now in process: assembling the finished components against the east wall of the house in Tucson, AZ. Soon the blazing sun and wickedly wet monsoon season will test this prototype. Time will tell the story.

Build out of the Earth Arch continues, a new fan installed in the first prototype, data gathering continues,

Rod applying Smith’s Expoxy Sealer

Gluing of planks and gussets completed

and a client’s Entry Arch is assembled…

One of the design principles for Nurse Tree Design is to keep electrical use to a minimum in cooling and heating the arch. I’m working on an evaporative cooling system with a 12 volt variable speed fan powered by a deep discharge battery. The battery will be charged by a 100 Watt Polycrystalline Solar Panel. These pictures show the development process thus far. Next step will be to build the housing for the evaporative medium and polytube water delivery system, which will be connected to the drip irrigation system.

100 Watt 12 Volt Polycrystalline Solar Panel

 

The journey of Dale’s arch from initiation to completion was long (September 27th 2015 proposal, April 25th 2016 completion). The design and creation of pattern files for CNC milling took until January to submit. Errors in the initial files further delayed assembly of the components. New standards for marine grade epoxy sealer and varnish required long lead times for procurement and additional time for applying the finishes. A new approach to the end cap framing was also time consuming. However, Dale is pleased with the result, as am I.

Concrete board installed on foundation frame for hugelkultur bed

Completed Nurse Tree Arch full size prototype

Dutch door open on arch