Fertilizers and micro-nutrients play a big role in the growth and health of your plant, as well as the development and growth of flowers and fruit. Each element aids the plant in some aspect.
In the plant world, the major role of phosphorous, is during the flowering and fruit set stage. It promotes flowers in all plants. Pumpkins are no exception.
After your pumpkin vines have grown several feet in length, it’s time to ease back on the Nitrogen, and use a fertilizer high in phosphorous. Even if your plant has begun to produce flowers, you apply a high phosphorous fertilizer. Your plants will respond, by producing more flowers, increasing the likelihood of pollination.
Important tip: Too much nitrogen in the soil can delay the onset of flowers and fruit set.