With the rising global human population, decreasing mass of arable land, increasing demand for food and the emergence of biotic and abiotic constrains to crop production in the advent of climate change, the future of food security stares at intensified production under controlled environments such as greenhouses. Cowpea [Vigna unguiculata (L.) Walp.], is an economically and nutritionally important vegetable crop widely cultivated by smallholder farmers both for subsistence and income generation. Uprooting the entire plant as a form of harvest is common in open-field subsistence farming systems. However, little is known about the effect of harvesting regimes on total productivity of cowpea under greenhouse conditions. This study was conducted in a greenhouse at Mundika Boys' High School farm, Busia County with an objective of evaluating growth and yield of cowpea (M66 variety) in response to different harvest regimes under controlled (greenhouse) conditions. Plots of cowpea stands/clusters each with four plants were subjected to three different treatments, i.e., harvest 1 (H1), harvest 2 (H2), harvest 3 (H3) and a control (no harvest or H0) in a randomized complete block design. Overall crop yield was measured by the number of trifoliate leaves (NTL) and plant height (PH) at 7-day intervals. Data collection was initiated at week 1 (for PH) and week 2 (for NTL) after emergence. The results revealed significant differences in both PH and NTL between H0 and H1, H2, or H3 (p≤0.05), implying that cowpea yields can be significantly improved by applying harvesting regimes to vegetable-only production systems. For PH, maximum values were obtained for H1 and H3. Thus, farmers can obtain higher vegetable productivity by harvesting cowpea for consumption or sale at intervals, as opposed to a one-time mass harvesting.