Any pumpkin-growing foray should start with the same thing: space—and plenty of it. Choose a location for growing pumpkins with a minimum of six to eight hours of full sun and a lot of room; vines can grow to more than 20 feet long.
Pumpkins prefer well-drained soils high in organic matter with a pH of 6 to 6.5. (Testing your soil in the fall allows you to adjust the pH accordingly before spring planting time arrives.) For all but the northernmost zones, pumpkins can be planted from seed after the danger of frost has passed and the soil temperature has reached 60 degrees F. Northern growers can start pumpkin seeds indoors in peat pots three to four weeks before transplanting them outdoors, again, after the danger of frost has passed.
Small farms can plant pumpkin seeds individually by hand, but for larger acreage, mechanized planting may be desired. Adam Voll, farm manager of Soergels Orchard in Wexford, Pa., uses a special technique for planting larger fields of pumpkins. (The farm grows 23 acres of squash and pumpkins.)
“We’ve been experimenting a little with this,” Voll says. “Typically, we’ve plowed and worked the ground into a fine seed bed. We still do a lot of that, but I’ve started doing more strip tilling. I have a machine that uses a sub-soil tooth, and then with a few disks and a rolling basket, I get a great seed bed in one pass. It saves time and is reducing the erosion and helping the soil. I will typically do this in a rye field or an old hay field so that the organic matter on top then helps with erosion and keeps the weeds down. We’ve also planted some on plastic. We use trickle irrigation under the plastic and have gotten great results.”
All pumpkins grow the same, no matter how much space you have to dedicate to their production. Pumpkins are monoecious, meaning the male flowers are separate from the female flowers on the same plant. Male flowers arrive first, ensuring ample pollen is available when the females open a few days later. You can tell the male flowers from the females simply by looking: Males are born on straight flower stalks, while female flowers have a swollen base that develops into the fruit once pollinated.
The pumpkin flowers are pollinated by insects, including many species of bees, flies and beetles (including the dreaded cucumber beetle), so to maximize pollination, plant plenty of flowering plants in and around the garden. The more flowers you have around, the more pollinators will be present in the garden. Hand pollination is possible, too; although, it’s only necessary if problems with pollination have occurred in the past or you need to control pollination for seed production.
Once the pumpkin seeds have germinated, mulch between the plants very well.
“We use a good bed of straw,” notes Gettle. “Once the vines get growing, it’s hard to weed around them. And the straw keeps the fruits clean and off the ground.”
Mulching also retains soil moisture, and pumpkins use a lot of water. Gettle recommends protecting pumpkin vines with floating row cover until they flower.
“Row cover is probably the No. 1 way to control squash bugs organically,” he says.
The row cover should stay in place while the pumpkin plants are young and vulnerable; it serves as a physical barrier between the plant and the pest. The cover is then lifted when the plants come into flower to allow for pollination. By that time, the pumpkin plants are mature enough to fend off any subsequent attacks, and the fruit are more likely to reach maturity. It helps deter cucumber beetle damage, as well.
With many types of squash and pumpkins, powdery mildew is likely to be an issue, especially during rainy summers. This dusty, white mildew appears on the leaves and is prevented, first and foremost, by choosing resistant varieties; secondly, by spacing plants properly to provide adequate air circulation and allow plants to dry quickly; and thirdly, with regular applications of potassium bicarbonate-based fungicides or compost tea. Although powdery mildew seldom kills plants (it’s primarily an aesthetic issue), when combined with pest issues or other plant stressors, it can result in plant death or decreased production.
“The weather has always been our biggest challenge,” says Voll. “Rainy, wet seasons make it tough with diseases like powdery mildew and also at harvesting time. But hot and dry makes it harder for watering and keeping the size up on the pumpkins.”
As the growing season progresses, the pumpkin fruits will begin to set and mature. You’ll know they’re ripe when the rind hardens and the vine begins to die. When the fruit is fully ripe, the skin should be tough to puncture with a fingernail, and the mature skin color should be fully developed. When harvesting pumpkins of all types, leave the stem on as long as possible. If it breaks off, the fruit will start to rot at the stem base, and the storage capacity is greatly diminished.
All types of winter squash, including pumpkins, are best stored on cardboard sheets in a cool place like a basement or a root cellar. Depending on the variety, expect a shelf life of anywhere between two months and one year.