Pumpkins are hungry things and they will eat up all the fertilizer that you feed them, but you can overdo it if you are not careful. Preparing your soil in advance with a nice all-purpose veggie soil can help you to ensure a solid base of nutrient amounts if you are worried or even better, prepare half of your space that way and leave the other half alone so that you can learn your local soil and what works through trial and error. To give you an idea of what kind of fertilizer they go through, commercial pumpkin farmers use about 2 pounds of nitrogen, then 3 pounds of phosphorus, and about 6 pounds of potassium for approximately 1000 square feet of pumpkin patch space.