Manuka oil was applied in combination with surfactants and other organic herbicides for a total of 10 different treatments. Three surfactants (Nu Film P, Agral 90, and yucca extract) and two essential oil based organic herbicides (clove–cinnamon oil and citrus oil) were tank-mixed with manuka oil. Herbicide treatments were analyzed against two checks (weedy and weed-free) in eight unique scenarios to determine what tank-mix options enhanced the preemergence (PRE) and postemergence (POST) efficacy of manuka oil. The eight unique scenarios included two locations (Simcoe and Ridgetown, ON), two crops (sweet corn and tomatoes), and two planting dates (early and late). Crop yield and visual weed efficacy data indicated that manuka oil had very weak PRE herbicidal properties in field scenarios. Manuka oil based treatments caused minimal crop injury on recently transplanted tomatoes and newly emerging sweet corn seedlings. Manuka oil was able to provide good weed control when applied POST either alone or in tank-mixes. The efficacy of manuka oil increased when manuka oil was used as a tank-mix partner compared with manuka oil applied alone.