There is insufficient information available on the effect of temperature and other environmental factors on pests and the beneficial insects that are used to manage them. Using fungus gnats, and beneficials Steinernema feltiae and Atheta coriaria, on pansy as a model system, we found that increases organic matter content of soilless mixes and higher moisture content of soils increased the number of fungus gnats produced. Lower temperatures extended the time to peak emergence of fungus gnats relative to warmer temperatures by approximately one month. Nematodes reduced the number of fungus gnats produced under warm and cool temperatures, but the effect was greater under cool temperatures. On-farm trials of nematodes for fungus gnat management had variable results but anecdotally supported on-campus research. Research results led to the development of a fact sheet “Practical Suggestions for Managing Fungus Gnats in the Greenhouse”. Based on an on-line survey, 50% of growers responding had changed practices based on information learned from this project.