How Do Pumpkins Deplete Soil?

Nitrogen

• Nitrogen is one of the first nutrients the sprouting pumpkin seed will utilize from the soil. Nitrogen is necessary for leaf growth and the pumpkin plants will produce hundreds of leaves within a matter of weeks. One pumpkin plant needs 2 lbs of nitrogen per 1,000 square feet. Since one pumpkin vine covers up to 2,500 square feet, you will need 5 pounds of nitrogen for one plant.

Potassium

• Cucurbits like the squash plant need almost double the amount of potassium as nitrogen from the soil to produce fruit. Since most soils cannot sustain that amount of depletion two years in a row, crop rotation in addition to soil amendments with compost or manure is necessary before planting pumpkin again.

Phosphorus

• Phosphorus is necessary for root formation and fruit set. Normally, the soil will have enough phosphorus for a growing season and then the addition of compost or plant matter replenishes it over time. Since pumpkins are heavy feeders, the phosphorus levels will drop in availability for the next year.

Micronutrients

• If your pumpkins are soft-fleshed and not sweet, the soil is probably lacking in micronutrients. This would include minerals that the plants usually use in a much smaller quantities, such as iron, manganese, copper. Pumpkin plants pull the minerals through their root system to meet the demands of the growing fruits.