We all want that giant, magical pumpkin come harvest time. Here are a few tips to get you there. Pumpkins are related to cucumbers, melons, summer squash, zucchini, and winter squashes and all of the vegetables in this family will benefit from this treatment. Warm soil. In Vermont wait until early June to put out the plants--a good rule of thumb is to wait until we have had a few nights above 50 F degrees. Transplants do better than seeds since you will have a head start on the season and don't risk having seeds rot in cold soil or be eaten by the local rodent. It's best to keep two plants together when transplanting since the larger volume of foliage will help shade out weeds later in the season.
A raised bed or mound. This will help warm the soil and improve drainage. It also gives the plants' shallow roots a place full or looser soil to spread without strain.
Lots of fertility. Compost is a must for successful pumpkins, squashes, cucumbers and melons. At home, we use rotted donkey manure (thanks to Pokey and Rosy) mixed with well composted yard debris (leaves, grass clippings) and food scraps. More can be learned about compost at the Vermont Compost Company website. A little granular fertilizer can be used as well if you do not have access to good compost and/or very poor soils. A soil test is always a good idea, and can be done easily at your local extension office.
Adequate water. One inch a week. That means that if it does not rain, you should gently pour about 3 gallons of water at the base of your plants. A slow drip irrigation system or soaker hose is a great option as well.
Full sun. There is no compromise on this one. The plants must have at least 8 to 10 hours of full sunlight.
Lots of room. Plants (actually, groups of 2 plants) should be at least 3 feet apart. They need that much space for proper ventilation and so that the flowers and foliage are exposed to pollinators and sunlight.
Pollination. Plant a few bee friendly plants such as calendula, borage, mint and salvias around your garden to attract bees and other beneficial insects. Cucurbit plants have male and female flowers on each plant and have to be pollinated by insects. Welcoming bees to your garden will help yields since more female flowers will become pollinated--the only way for them to produce fruit.
Harvest at the right time. Winter squashes and pumpkins should be harvested when the skins are hard and cannot be pierced by your thumbnail. Summer squashes and cucumbers and zucchini should be harvested at whatever stage you like to eat them, from baby to baseball bats. Watermelons are harvested when the tendrils on either side of the attaching stem are dead and the yellow spot on the bottom of the fruit (where it rests on the ground) is a deep yellow, and when thunking the fruit with your knuckle produces a hollow sound. Cantaloupes are ready when they slip off the vine with a gentle tug (called the "half slip stage"). Melons take a little trial and error to learn to harvest at the right time, but a good rule of thumb is "if in doubt, wait."