Pumpkins (Cucurbita maxima) add lush vines and vibrantly colored gourds to backyards throughout U.S. Department of Agriculture plant hardiness zones 3 through 9. Interest in pumpkins spikes around Halloween, but there's nothing spooky or scary about planting this annual vine if you know exactly when, and how, to start.
Check the Calendar
Pumpkins are a warm-season vegetable, and frost can quickly kill the young plants. Wait until the last frost date in your region has passed before planting pumpkin seeds. For example, in Illinois, pumpkins are generally planted in mid-May. In Virginia, pumpkin seeds are typically sown in mid-June. And in Texas, the last frost dates range from February to March in southern portions of the state and March to April in northern Texas.
Review Soil Temperatures
Once the last frost date in your region has come and gone, wait for the soil to fully warm up. Although pumpkin seeds can germinate in soil as cold as 60 degrees Fahrenheit, wait until soil temperatures are at least 70 degrees. In general, pumpkin seeds experience optimal germination when the soil temperature hovers around 95 degrees.
Watch the Sun
For vigorously growing vines and the biggest pumpkin gourds, pumpkins need full sun exposure. Wait to plant pumpkin seeds until the planting site you've selected receives at least eight hours of direct sunshine every day. More is always better. Consider planting pumpkin seeds on an east- or west-facing side of your property to maximize sun exposure.
Prepare the Soil
Once temperatures and sunlight hours indicate it's time to sow your pumpkin seeds, prepare the planting site. Mix approximately 4 inches of compost into the top 12 inches of soil. Compost enhances soil drainage and helps keep the soil warm, which improves pumpkin health.
Using a spade, pile the prepared soil into hills. Hills heat up faster during the day and drain better. Pumpkins need a lot of space. Each hill needs to measure at least 50 square feet. If you're making multiple hills, space each hill apart by approximately 6 feet.
Planting the Pumpkin Seeds
Bury each pumpkin seed approximately 1 to 1 1/2 inches deep. Sow up to four or five seeds per hill, spaced equal distances apart in a circle in the middle of the hill. Water once a day or as necessary to keep the soil consistently moist. The baby pumpkin plants will emerge within 10 days. Once the plants are a few inches high, thin the hill by pinching off all but the two or three strongest pumpkin plants. Provide them with about 1 inch of water per week.