Submit a soil sample to your county Extension office for forwarding to the Agricultural Service Laboratory at Clemson University for an analysis to find out whether you need to adjust the pH where you plan to plant pumpkins. The same lab will test your soil to see what nutrients you might already have in your soil or which are lacking. If pumpkins will be grown after a legume or another green manure crop, less fertilizer is needed. As a nitrogen side-dressing, spread a half cup of calcium nitrate around each plant when fruits start to form. Do not use ammonia-based nitrogen, such as ammonium nitrate, or you are sure to burn the plants.
Weed control can be difficult after vines have spread.
You may want to cover the soil with wheat straw, compost, or pine straw before vines spread. If wheat straw is used as a mulch, apply an additional half cup of calcium nitrate when side-dressing. Pumpkin roots are close to the surface of the soil, so be careful when cultivating near the main stem.