Optimizing Butternut Squash (Cucurbita moschata) Growth and Yield: The Role of Sowing Time and Nutrients

Butternut squash (Cucurbita moschata) is an annual vine plant with large, lobed leaves, trailing branches, and monoecious yellow-orange flowers. It’s a winter squash of the Cucurbitaceae family, a hybrid developed in 1944 by crossing pumpkin and gooseneck squash. Sowing time of butternut squash critically influences crop phenology, growth, and yield by modulating environmental interactions. This study aimed to determine the optimal sowing time, evaluate the effects of nutrient management practices, and investigate their combined influence on maximizing the growth and yield of butternut squash under regional agroclimatic conditions. Optimizing sowing time and nutrient management is critical for improving butternut squash productivity, yet their synergistic effects remain understudied in subtropical climates. A two-year field experiment (November 2022–March 2023) at Sher-e-Bangla Agricultural University, Bangladesh, evaluated three sowing dates (T1: 25 November; T2: 10 December; T3: 25 December) and four nutrient regimes (F0: Cowdung 20 t/ha; F1: N₅₀P₂₀K₄₀S₁₀Zn₁.₀ kg/ha; F2: N₇₅P₃₅K₆₀S₂₀Zn₂.₀ kg/ha; F3: N₉₀P₅₀K₈₀S₃₀Zn₃.₀ kg/ha) using a Randomized Complete Block Design (RCBD) with three replications. Early sowing (T1) significantly enhanced reproductive outcomes, yielding 14.66 female flowers/plant, 5.99 fruits/plant, and 10.33 t/ha, whereas late sowing (T3) reduced these parameters to 9.46 flowers, 3.55 fruits, and 3.78 t/ha. Among nutrient treatments, F2 maximized yield (10.00 t/ha) with 12.05 female flowers and 5.99 fruits/plant, outperforming F1 (10.16 flowers, 3.88 fruits, 5.13 t/ha). Synergistic effects were pronounced: the T1F2 combination (25 November + N₇₅P₃₅K₆₀S₂₀Zn₂.₀ kg/ha) achieved peak productivity (17.83 flowers, 7.16 fruits, 13.35 t/ha), while T3F1 (25 December + N₅₀P₂₀K₄₀S₁₀Zn₁.₀ kg/ha) resulted in minimal yield (7.17 flowers, 3.5 fruits, 2.30 t/ha). These findings demonstrate that early sowing paired with balanced NPKSZn fertilization (F2) optimizes resource allocation and yield in butternut squash, offering a scalable strategy for subtropical agroecosystems.