The Devonian Gardens is a three-acre horticultural refuge on the top floor of The CORE Shopping Centre in Calgary, Alberta, Canada. One of the largest indoor gardens of its kind, it boasts more than 10,000 ground cover plants, 250 trees, a 900-square-foot living wall, koi ponds, and a children’s play area. This impressive botanical oasis, perched above 116 retail stores, is maintained by The City of Calgary Parks. Since 1977, Devonian Gardens, with its imported exotic plants and tropical trees, has served as an alluring retreat for Calgarians and tourists – especially during the long winter season.
The City completed a major renovation of the facility in 2012. Changes included a “punch through” of the floor space onto the mall below leaving a wider, taller open-air circulation space and the insertion of a 2-block long, continuous skylight. The massive “Winter Garden” shares the same airspace with a shopping area and is not in a greenhouse environment.
Leveraging LoRa Technology to Monitor Garden Health
The plants and trees within Devonian Gardens are precious assets and some are irreplaceable. Others have been recently transported great distances and craned onto the fourth-floor roof to be brought into the garden. The main challenge for the indoor garden is creating a healthy environment for 43 planter beds, some with multi-levels, of tropical indoor plants and 27 different species of trees within a three-acre area.
Devonian Gardens has beds varying in size and depth. A soil monitoring sensor connected to the Internet of Things (IoT) is part of the Proof of Concept (PoC) to measure volumetric water content (VWC), soil temperature and electrical conductivity (EC). VWC provides the ability to understand irrigation performance against the species’ requirements. EC measures the salinity of the soil which helps in fertilization for optimal plant health. The combination of light, water, air, and soil characteristics helps reduce disease and penetration of pests. By utilizing Semtech’s LoRa® devices and wireless radio frequency technology (LoRa Technology)to gain an understanding of these fundamental characteristics, the City of Calgary can easily and efficiently manage these assets despite the environmental challenges.
Creating Tropical Conditions Indoors with IoT
One of the most difficult tasks is keeping the plants well lighted so they can experience consistent and healthy growth throughout the year. Danielle Zadunayski, horticulturist at Devonian Gardens since 2011, noticed some trees were exhibiting signs of light stress. What appeared as big and healthy growth, was, in fact, the canopy compensating for low light levels. The leaves grew to much larger surface areas in order to receive more light, causing the trees to become top heavy and list dangerously to the side.
To test the technical capability of LoRa-enabled photosynthetic active radiation (PAR) sensors in creating and maintaining appropriate lighting throughout the seasons, Devonian Gardens installed a PAR sensor in one flower bed as a PoC. With PAR readings from different positions, specialists are able to leverage IoT to quantify light spatially in the garden. A spatial representation will help in future species selection and placement, maintenance, and in future lifecycle of lights for optimal plant health. Temperature, humidity and barometric pressure sensors measure vapor pressure deficit (VPD) and characterize this over the physical space to ensure optimal plant health. VPD is the difference between the amount of moisture in the air and maximum amount of moisture the air can hold.
The positive results of the PoC has led to the development of a business case to implement LoRa-based sensors across the entire gardens. Download the complete Devonian Garden use case, and learn more about how LoRa-based solutions are revolutionizing smart agriculture.
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