If you have a long-enough growing season, just plant your seeds directly in the ground once the soil has warmed up in the spring (to about 70 degrees) and all threat of frost has passed!
If you live in an area that has a short growing season, you should start your seeds indoors next spring about 4 weeks before your last frost date. Peat pots are handy for this, since pumpkins don’t like having their roots disturbed during transplanting. Sow 2 to 3 seeds in each peat pot. Once they have germinated and are growing well, choose the best one to keep in each pot and clip the others off with scissors. After the soil has warmed, pop the plants—pot and all—into the ground.
Pumpkins are heavy feeders, so enrich the soil with plenty of compost and well-rotted manure. A spot in full sun with soil pH of 6.5-6.8 is ideal. Pumpkin vines can grow quite long, so give them plenty of room to run. Cover the new plants with a lightweight row cover to keep them warm and protected from insects early in the growing season. Once they have started to blossom, the covers need to come off so that bees can pollinate them.
Since much of a pumpkin’s weight is water, make sure they get about 2 inches of water a week. Mulch helps to keep the soil constantly moist. Side-dress your growing plants with more composted manure during the summer and foliar feedings of liquid fertilizers like fish emulsion and seaweed are excellent for supplying trace minerals.
Once your pumpkins have turned orange and the rind has hardened enough so that you can’t pierce it with your fingernail, they are ready to pick.
Mature pumpkins can stand 1 or 2 light frosts, so you can leave them in the garden until frost kills the vines. To harvest, cut a long stem and pick the pumpkins up by their body and not the stem to keep from snapping it off. A pumpkin with the stem intact will last longer.
Your pumpkin will also last longer if it is cured outside in the sun for 5 to 7 days after harvesting or indoors in a warm—85 degrees F—spot for 7 to 10 days to further harden the skin.
After curing, keep them in a cool dry place until you are ready to carve them!
If you have had a bumper crop, be sure to share them with friends and family or you could even sell them! Be sure to save some more seeds for next year!