College of Agricultural, Human, and Natural Resource Sciences

Department of Horticulture

Rita L. Hummel

Associate Professor/Associate Scientist/Extension Horticulturist
(WSU faculty member since 1985)

Areas of Interest

Environmental Horticulture

  • Develop recycled organic materials as substrates and nutrient sources for nursery and greenhouse container production and landscape use
  • Enhance water conservation in container production and landscapes
  • Improve longevity of trees and shrubs in the landscape by preventing root structural defects
  • Develop production practices for difficult to grow native plants
  • Determine woody plant adaptation to rain gardens under Pacific Northwest environmental conditions

Educational Background

  • Ph.D., University of Minnesota, Horticulture
  • M.S., University of Minnesota, Horticulture
  • B.S., South Dakota State University, Botany, Horticulture


  • Washington State Nursery and Landscape Association Educator of the Year 2009
  • USDA Plant Hardiness Zone Map Technical Review Team

Teaching Responsibilities

Program Personnel

  • Morgan Fish, MS,  2013-2015

Selected Publications

  • Hummel, R.L., Craig Cogger, Andy Bary, and Robert Riley. 2014. Marigold and pepper growth in container substrates made from biosolids composted with carbon-rich organic wastes. HortTechnology 24(3):325-333.
  • Hummel, Rita L. and Virginia Lohr.  2014.  Urban/Suburban Streamside Demonstration Landscape Design and Implementation: Clarks Creek.  Report to Washington Department of Ecology.
  • Hummel, R.L., M. Elliott, G. Chastagner, R.E. Riley, K. Riley, and A. DeBauw.  2013.  Nitrogen fertility influences growth and susceptibility of rhododendrons to Phytophthora ramorum HortScience. 48(5):601-607.
  • Hummel, R.L. and C. Cogger. 2012. Struvite can serve as a renewable phosphorus source for greenhouse crop production. B&B Magazine 64(4):16-17.
  • CSANR Webinar ‘Struvite as a Phosphorus Fertilizer Source for Greenhouse Crop Production.’
  • Ophardt, M.C., and R. L. Hummel. 2011. Planting Trees and Shrubs in the Landscape. WSU Ext. Fact Sheet FS047E. pp 10.
  • Krucker, M., R.L. Hummel, and C. Cogger. 2010. Chrysanthemum production in composted and noncomposted organic waste substrates fertilized with nitrogen at two rates using surface and subirrigation.  HortScience. 45(11):1695-1701.
  • Scagel,  C., R. Regan, R. L. Hummel, and G. Bi.  2010. Cold tolerance of container-grown green ash trees is influenced by nitrogen fertilizer type and rate. HortTechnology. 20(2):292-303.
  • Hummel, R.L., E. Evans, and R. Riley. 2009. Effect of Mechanical Root Disruption at Transplant on Short- and Longer-term Growth and Survival of Scotch Pine (Pinus sylvestris) and Shore Pine (Pinus contorta var. contorta). pp 211-221.  In: G.W. Watson, L. Costello, B. Scharenbroch and E. Gilman (eds.), The Landscape Below Ground III: Proceedings of an International Workshop on Tree Root Development in Urban Soils. International Society of Arboriculture, The Morton Arboretum, Lisle, IL.
  • Cogger, C., R. Hummel, J. Hart, and A. Bary. 2008.  Soil and redosier dogwood response to incorporated and surface-applied compost. HortScience. 43(7):2143-2150.

Rita HummelOffice: WSU-Puyallup
2606 West Pioneer
Puyallup, WA 98371-4998

Phone: 253.445.4524

Department of Horticulture, PO Box 646414, Washington State University, Pullman, WA 99164-6414, 509-335-9502, Contact Us
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