When to Sow: April-May Maturity: September to October
Germination: 7-10 days Full Sun
Plant in full sun in an area that has good air circulation. Pumpkins grow best in moderately rich soil, but for best results plant them in hills enriched with compost or lots of good organic matter.
Starting Indoors: Sow 2-3 seeds in 2" modules (peat or cardboard containers are ideal) 3 weeks before transplanting outdoors. Be careful not to over water, as squash seeds are quick to rot in overly-moist, airless compost or soil.
Thin to strongest 1-2 plants per module. Harden off gradually and transplant outside after all danger or frost has passed and the weather is warm and settled. (In most climates this is towards the end of May.) Like all squash, pumpkins have a very tender rooting system, so be extra careful not to disturb.
Give them plenty of room to spread out, 25’ (7 to 8 m) from each other. They are vigorous growers and heavy feeders, and good soil is important.
Direct Seeding: Sow in late spring when the soil has warmed to around 70°F (21°C) and the danger of frost has passed. Sow 1-2 seeds. Plant 25’ apart and 1/2-1" deep. Thin to 1 plant per spot.
For best results, plant at the top of a shallow mound. As the squash grows it will produce a mass of white roots on the surface of the soil. Cover these with compost or well-rotten manure as they appear.
Maintenance
Keep pumpkins well watered at every stage of their development. Pumpkins are heavy feeders and can enjoy up to weekly feedings of liquid seaweed or other similar fertilizers. Mulch well to discourage weeds and conserve water.
Since pumpkins take a long time to mature, it’s helpful to get them off the ground once the fruit has set. (Too much contact with the wet earth can cause them to rot.) You can do this by placing things like wood, bricks, or tile underneath them so that they’re not in contact with the soil.
Harvesting
Harvest when fruit is fully mature and the foliage has died down (but before the first frost). Cut stems about 1" from the fruit, ideally after the stem has dried and the skin has hardened. (Again pumpkins are not freeze-hardy and must be harvested before the first freeze of the year.) Handle the fruits carefully to avoid scratching or bruising them. Leave in the field for 5-7 days in full sun to dry and toughen the skin.
With good storage, Jack O’ Lantern pumpkins are best for carving, but they can also be eaten (they just won’t be as sweet as a variety grown specifically for eating).
Companion Planting
Pumpkins do well with all nitrogen-fixers like beans and peas, and can be planted alongside corn and benefit from ice radishes, nasturtiums, and borage.