Current cultivation of vegetables to meet food security standards requires the use of pesticides which reduce losses from pests and diseases. A cross-sectional survey for pesticides use in tomato farms was conducted in Mwea, Kenya to assess the practices and constraints faced by the farmers. Gender, level of education, the use of pesticides in farms, experience in tomato farming, list of common pesticides, periodicity of pesticides spray in farms, approximate last day for pesticides spray, reason for pre-harvest period and pesticides spray in post-harvest time were investigated. Results revealed that, 90% farmers were men and 10% were females; 38.5% and other 38.5% attended primary and ordinary schools; 15 and 4% had advance and university levels. About 69% of respondents knew pesticides through other farmers; 31% through agrovets, extension officers and agricultural experts. Around 56% farmers knew the names of pesticides through other farmers, 44% got them from agrovets, agricultural officers and chemical companies. About 98% respondents use pesticides approved by government, 96.2% listed each between 2 and 11 names of pesticides mostly used in tomato farming. Almost 93% spray pesticides once a week in farms and 76.9% observe at least 7 days for the preharvest period. Relatedly, 84.8% assert that waiting for the pre-harvest time is the culture of farmers in the region. Surprisingly, 6% spray pesticides in the post-harvest period, while 84.6% assert that the preharvest moment is to avoid pesticides in post-reap. Although key questions found good answers from farmers, the quality of their knowledge is limited, shows missing information and needs reinforcement. Agrovets appear as the legal authority and act as key informants for most farmers. Most farmers rely on other farmers or agrovets-displacing the low or nonexistent contribution of agricultural extension officers. Capacity building and periodic updates for agrovets and farmers are required.