Pumpkin & Squash

Pumpkins and winter squash are true heavy feeders with a three-phase nutritional cycle that mirrors their dramatic growth habit — from seed to potentially 1,000+ pound fruit in a single season for giant varieties. The Cornell University pumpkin fertility guide emphasizes that while these cucurbits demand substantial nutrition, the nitrogen balancing act is critical: 75-100 pounds of nitrogen per acre is the recommended range, and higher rates actively suppress fruit production by promoting excessive vine growth that shades female flowers and interferes with bee pollination. The nutritional phases are distinct and non-negotiable. Phase one (germination through vine run) demands moderate nitrogen to build the massive leaf canopy that will power fruit development. Phase two (flowering through fruit set) requires a dramatic shift to phosphorus and potassium — a 6-10-10 or 5-10-10 formula — because continued high nitrogen at this stage causes blossom drop and poor fruit set. Phase three (fruit expansion through maturity) is all about potassium, which drives the rapid carbohydrate loading that builds thick rinds and dense sweet flesh. Calcium is also critical during fruit expansion; deficiency causes blossom end rot identical to that seen in tomatoes, particularly when soil pH drops below 6.0. Pumpkins grown on land where legume cover crops preceded them may need little to no supplemental nitrogen — the residual soil nitrogen from the legumes is often sufficient for the vegetative phase. Banding fertilizer rather than broadcasting is recommended because of the wide row spacing typical of vine crops.