Pumpkins need a fertile, moist soil, preferably amended with large amounts of organic matter, in order to grow well. Make sure that the soil is well-drained with a pH ranging between 6.0 to 6.5. Moisture and high soil fertility is essential for good health since the plants have high requirements for both. Mix in well-made compost, peat moss or balanced organic fertilizer in soil over a large planting area prior to planting. Avoid planting in soil where other vine crops like cucumbers or melons were cultivated in the past two years. Water pumpkin vines regularly to help plants live well.
Allow plenty of space between the plants for optimal growth. Space the hills of vining varieties 5 to 6 feet apart and plant the seeds at a 1-inch depth. Space the rows 10 to 15 feet apart. Plant the semi-bushy varieties 1 inch deep with row spacing at 8 feet and hill spacing at 4 feet. The miniature pumpkins seeds are also planted 1 inch deep with rows spaced 6 to 8 feet and plants at 2 feet. The bush varieties are best spaced at 3 feet with 4 to 6 feet between rows.
Conduct a soil test to determine the exact soil requirements for lacking nutrients. On a general note, spread 10 pt. of 5-10-10 fertilizer over the soil for every 100 feet of rows to help plants live well. Apply 20 to 30 lbs. of nitrogen and 60 to 100 lbs. of potassium per acre or 1 pt. of 13-0-44 per 100 feet of rows as a side dressing after three to six weeks of seeding. Start the side dressing 6 to 8 inches away from plants on both sides of the row.
Planting at the right time is just as important as after-planting care. Pumpkin seeds germinate best in a warm soil at soil temperatures of 60 to 65 degrees F at the depth of 4 inches. If planted too early and in cold soil, the seeds will fail to germinate and the seedlings are prone to frost damage. Wait until all danger of frost has passed. Seeds that are planted too early are also likely to soften and rot.