Grant Edward Johnson

Grant Edward Johnson

Assistant CE Urban Agriculture Technology Area Advisor

M.S. Horticulture and Agronomy, University of California Davis. 2023
B.S. Biological Sciences, California Polytechnic State University San Luis Obispo. 2013
Irrigation management, horticulture, nursery crops, indoor production, urban agriculture

Grant Johnson serves as the Urban Agriculture Technology Advisor for Los Angeles and Orange Counties, providing impartial, research-driven insights to optimize plant production in urban environments. With a focus on indoor production, such as greenhouses, his diverse clientele includes nurseries, commercial growers, school districts, and community gardens. In his dynamic role, Johnson actively shapes the future of urban agriculture by tackling challenges through economies of scale. This involves creative exploration of horticultural topics related to irrigation, plant culture, and agricultural technology innovations that drive the future of farming, ensuring technological advancements that benefit a wide range of urban farming practitioners.

Peer reviewed

  • Pitton, B. J. L.; Wikramanayake, A. M.; Johnson, Grant (2023). Mechanically-Incorporated Controlled-Release Fertilizer Results in Greater Nitrogen and Salt Leaching Losses from Soilless Substrate in Containers. Horticulturae. 9:42.

  • Redekar, N., T. Bourret, J. Eberhart, G.E Johnson, B.J.L. Pitton, D.L. Haver, L.R. Oki, J. Parke. The population of oomycetes in a recycled irrigation water system at a horticultural nursery in southern California. Water Research, 2020, 183, 1–10.

  • Pitton, Bruno J.L.; Johnson, Grant E. (2022). Water use and estimated evapotranspiration at a California container plant nursery. Acta Horticulturae. 1335:651.

  • Pitton, B.J.L., G.E. Johnson, D.L. Haver, L.R. Oki. Water use and estimated evapotranspiration at a California container plant nursery. Full text article for International Symposium on Irrigation of Horticultural Crops. Acta Horticulturae, 1335, 82

  • Pitton, B. J.L., L.R. Oki, D.L. Haver, G.E. Johnson. The payoff of recycling nursery water. American Nurseryman, 2017, 21-23

Non-peer reviewed

  • Kim, Dohee; Johnson, Grant (2025). 2024 Annual Report. UC Cooperative Extension in Los Angeles County. November 11th, 2025. https://storymaps.arcgis.com/stories/8a1ea06636594b4d87cad3efde0b1305
  • Pitton, B.J.L.; Johnson, Grant E. (2025). A biological treatment technology to remove plant pathogens from irrigation water. UC Nursery and Floriculture Alliance Newsletter. August 10, 2025. https://ucnfa.ucdavis.edu/news/slow-sand-filters
  • Mukherjee, Amrita; Lofton, Esther N.; Johnson, Grant E. (2025). Comparative analysis of different biodegradable mulch uses in hill-side strawberry production. SoCal Urban Food Production. September 10. https://ucanr.edu/blog/socal-urban-food-production-blog/article/comparative-analysis-different-biodegradable-mulch
  • Mukherjee, Amrita; Johnson, Grant E.; Lofton, Esther N. (2025). Enhance Water and Nutrient Use Efficiency for Controlled Environment Agriculture. SoCal Urban Food Production. May 7. https://ucanr.edu/blog/socal-urban-food-production-blog/article/enhance-water-and-nutrient-use-efficiency-controlled
  • Johnson, Grant (2025). Pipe Dreams and Pressure Gauges: An Irrigation Training from UC Cooperative Extension. UC Nursery and Floriculture Alliance Newsletter. August 10, 2025. https://ucnfa.ucdavis.edu/news/ucnfa-summer-issue-2025
  • Merhaut, Don; Johnson, Grant (2025). Recognizing Water-Related Disease Issues in Container Nurseries. UC Nursery and Floriculture Alliance Newsletter. August 10, 2025. https://ucnfa.ucdavis.edu/news/recognizing-water-related-disease-issues-container-nurseries
  • Mukherjee, Amrita; Johnson, Grant E.; Lofton, Esther N. (2025). Share Your Insights, Receive a Free Water & Nutrient Efficiency Checkup! SoCal Urban Food Production. August 8. https://ucanr.edu/blog/socal-urban-food-production-blog/article/water-nutrient-survey
  • Johnson, Grant E.; Mukherjee, Amrita; Lofton, Esther N. (2025). Tertiary Treated Water: A Key to Sustainable Urban Farming. SoCal Urban Food Production. May 21. https://ucanr.edu/blog/socal-urban-food-production-blog/article/tertiary-treated-water-key-sustainable-urban-farming
  • Johnson, Grant E. (2025). UCNFA Advisors and LA Irrigated Lands Group Assists Growers with Irrigation and Nutrient Management Plans. UC Nursery and Floriculture Alliance Newsletter. April 08, 2025. https://ucnfa.ucdavis.edu/news/ucnfa-advisors-and-la-irrigated-lands-group-assists-growers-irrigation-and-nutrient-management
  • Lofton, Esther N.; Johnson, Grant E.; Mukherjee, Amrita (2025). Water Quality Requirements for Urban Food Production and Hydroponics. SoCal Urban Food Production. January 28. https://ucanr.edu/blog/socal-urban-food-production-blog/article/water-quality-requirements-urban-food-production-and
  • Mukherjee, Amrita; Lofton, Esther N.; Johnson, Grant E. (2024). Managing soil toxicity in urban farming system. SoCal Urban Food Production. August 30, 2024. https://ucanr.edu/blog/socal-urban-food-production-blog/article/managing-soil-toxicity-urban-farming-system
  • Volk, Emma; Johnson, Grant E. (2024). Optimizing Fertilizer Practices in Your Container Garden Part 1: The Basics. Californica. July 2024. https://productionhortucce.squarespace.com/blog/optimizingnutrientmanagement
  • Johnson, Grant; Pitton, Bruno J. (2024). Rethinking your fertilizer. Ball Publishing. 88:6. October. https://www.growertalks.com/Article/?articleid=27007
  • Spinelli, Gerry; Johnson, Grant (2023). Why Pressure Drops as Water Flows in a Pipe and Other Irrigation Mysteries. Summer Extension Connection Newsletter. Padilla, Robert. University of California Cooperative Extension. August, 2023. https://cesandiego.ucanr.edu/newsletters/Extension_Connection_Newsletter98783.pdf