Raising pumpkins can be a most unpredictable enterprise, says David Nagel, horticulture specialist for Mississippi State University's Extension Service.
“A major factor in the health of a pumpkin crop is how much rain a field receives,” he says. “A field that either receives a lot of rain or doesn't drain well will be susceptible to fungus or rot. Also, some fields may have serious virus problems and some may not, due to the many viruses carried by insects, which vary in how and when they attack crops. There's nothing so worthless as a pumpkin come Nov. 1.”
A pumpkin is a type of squash, and there are 60 different types of winter squash and 15 different type of pumpkins. As opposed to summer squashes, Nagel says, pumpkins will store for long periods.
Pumpkins need well-drained soils, he says, and they require a pH above 6.2. They'll start to die after 48 hours in water.
A pumpkin crop should be fertilized with a split nitrogen application, says Nagel. “A side-dress fertilizer application is recommended when vines begin to run. Soil test for P and K, and use potassium nitrate to side-dress if K is low, especially on sandy soils,” he says.
Some growers spray Boron after the pumpkins begin forming, but research hasn't proven the reliability of such a practice, although it doesn't appear to do any harm, horticulturists say.
Spacing requirements for pumpkins are as follows: bush is 10 to 18 square feet per plant, semi-vining is 12 to 32 square feet per plant, and vining is 25 to 50 square feet per plant.
“In some cases, that means one plant per 5 row feet, and in most cases that means planting by hand. You can adapt a planter with one hole drilled in a disc, or by using an old planter and taping up all of the holes but one,” says Nagel.
Insects and diseases always are problems in pumpkin production, he says.
“There are lots of them. The main problem with growing pumpkins, in fact, is a large number of production-limiting diseases. It's a given that you'll spray for diseases and that you'll spray for insects.”
Foliar diseases are common in pumpkin production, he says. “Downey mildew attacks when it's wet, and powdery milder attacks when it's dry, so you can't win. The same is true for viruses. There is no genetic resistance in pumpkins, which means you've got to control the thrips and aphids that carry the viruses. Those growers planting into sandy soils also need to sample for nematodes.”
Treatment coverage is as important as the material used, he adds. “Water is cheap, so make sure you get good coverage. If you cover every leaf with fungicide, the disease won't take hold.”
Timing also is critical, he says. “The best time to control insects is before they become insects — when they are egg masses.”
Nagel recommends getting one hive of honeybees per acre of commercial pumpkin production. However, the presence of hives also means that insecticide timing becomes even more critical.
Pumpkins generally are harvested about 100 days after planting. “The days to harvest number is extremely dependent on weather conditions. It can take anywhere from 60 days to 120 days for a variety to mature, depending upon temperature and rainfall conditions.”
There's one market for pumpkins, and that's Halloween, Nagel says. “It's better to be a little early than just-in-time. Most varieties today are bred to look good, not to produce a lot of food, because folks will pay a lot more money for decorating than they will for eating.”
He advises growers use color as their guide. “When they get to be the right color, the pumpkins are mature, and it's time for harvest. The general guideline for the Mid-South is to plant on the fourth of July and harvest on Oct. 1. Harvested pumpkins should be stored in a cool, dry area with temperatures between 50 and 55 degrees and relative humidity between 50 and 75 percent.”
There is a market for pumpkins, says Nagel. However, as a grower you can't guarantee the market you'll make a crop due to virus, insect and disease pressure.