Soon it will be time to start planting pumpkins. Generally for the eastern U.S., the planting month is July (or between June and July for western growers). Pumpkins are members of the Cucurbitaceae family, which also includes cucumber, muskmelons, watermelons and squash.
Pumpkins can be seeded in a greenhouse to transplant out into the field in about four weeks. However, pumpkins and other cucurbits have tender, fragile stems that can be easily snapped when transported or when removed from the cells. Seeding pumpkins directly into the field eliminates these problems. Since they are a warm season crop, do not seed pumpkins until the soil temperature reaches 60º F at a four-inch depth.
Plants grow best under warm and moist conditions. Pumpkins are monoecious, meaning that both male and female flowers are produced on the same plant. Pollen from the male flowers is transferred to the female flowers with the help of wind and bees. Fruit shape, size and appearance are quite variable, ranging from smooth and small (under three pounds) to ribbed and quite large (more than 90 pounds).
Pumpkins should be grown on well-drained soils having good water-holding capacity. Irrigation is a must to obtain optimum plant growth, uniform fruit set and development. Soil pH should be in the 5.8 – 6.6 range. The best average temperature range for pumpkin production during the growing season is between 65° and 95° F; temperatures above 95° F or below 50° F slow growth and maturity of the crop. Pumpkins require a constant supply of available moisture during the growing season. Water deficiency or stress, especially during the blossom and fruit set periods, may cause blossoms and fruits to drop, resulting in reduced yields and smaller-sized fruits.
Because pumpkins are a warm-season crop, they can be grown on raised beds with black or silver plastic mulch and drip irrigation tubing placed underneath for optimum plant growth and yields. The use of plasticulture in the production of pumpkins will increase soil temperature five to 10 degrees, conserves soil moisture, reduces weed growth and reduces fertilizer leaching under the bed as compared to bare soil. Fertilizer can also be injected through the drip irrigation system throughout the growing season. Yields under the plasticulture system can be twice as much as pumpkins grown on bare soil. Fertilizer recommendations should be based on soil test results, and soil tests should be taken every year.
Pumpkins can be planted as single rows with 30 – 40 inches between plants in the row and eight to 12 feet between rows, depending on plant type. Plant populations at this spacing are approximately 1,600 (for pumpkins in excess of 30 pounds) to 2,800 plants per acre (for pumpkins less than eight pounds).
Good weed control can be achieved with by using labeled herbicides. There are several pre- and postemergence herbicides labeled for pumpkins, depending on specific weed problems requiring control and stage of pumpkin growth. In addition, under mild infestation levels, early cultivation (if possible prior to vine running) can minimize weed problems.
Insect and Disease Control
Troublesome insects for pumpkin include the squash bug, squash vine borer and striped and spotted cucumber beetles. The squash bug adult lays maroon-colored eggs on both the upper and lower leaf surfaces. They suck plant sap from the leaves, resulting in dead, dried brown areas on the leaf margins. The squash vine borer larvae bores into the main stem at the base of the plant, cutting off water and nutrients to the plant. Striped and spotted cucumber beetles can transmit viruses to pumpkin, causing vines to wilt and die. Contact your local county Extension office to find out the optimum times to control pumpkin insects to protect your crop.
Harvest and Storage
Pumpkins are harvested when the rind is hard and not able to be easily punctured with a fingernail. Harvest fruit as soon as they are mature and prior to frost. Harvest by cutting stems off the vine, leaving a four- to six-inch stem attached to the fruit.
If maturity is late, pumpkin fruit with at least 40 – 50% of the fruit surface with orange color will continue to ripen. Use care in handling fruits to avoid wounds. Cuts and bruises in the rind are open to decay organisms that may cause a great deal of loss in the short run. Under proper conditions, wound areas can heal over by producing cork tissue. The protective tissue seems to develop best at relatively high temperatures and in a moist atmosphere.
A 10-day curing period after harvest at 80 – 85º and about 80% humidity before storage is often recommended for pumpkins. Many times this can be done in the field, or in windrows, in order to avoid excess handling and costs. At the end of the curing period, the humidity should be lowered to about 70% and the temperature kept between 50 – 60º F.
It is essential to keep the surface dry during the storage period. Any dry place that is as close as possible to the desired storage temperatures is suitable for storage of pumpkins and squashes. They keep best when not piled on top of each other but this may not be practical for most operations. Try to keep stacks at minimum heights, leaving room for good air circulation. Pumpkins in good condition can be held two to three months without problems. Temperatures below 40º for long periods can cause chilling injury and lead to fruit rots.
There are several marketing alternatives available to the pumpkin grower, including wholesale markets, local retailers (grocery stores), roadside stands and U-pick operations. Some farm stands and U-pick operations have developed value-added activities such as hay rides and harvest festivals to boost sales.
In wholesale marketing, one way growers can sell their pumpkins is to a supermarket chain, dealing with a produce buyer. The wholesale price is the lowest price per pound you will receive as compared with retail selling. Many times, there is no written contract, only a verbal contract. It’s possible that produce buyers can change their minds in an instant and decide they no longer need your produce, after you have incurred packaging and transportation costs.
Produce auctions can be a way for growers to sell large volumes of pumpkins that are not able to be sold through other marketing outlets. This is a way for growers to sell excess pumpkins. Be prepared to receive a low price if there is a large volume of pumpkins on the auction floor. Prices paid can fluctuate at auctions throughout the season, based on supply and demand.
Retail marketing options, such as roadside stands and U-pick operations, provide opportunities for you to receive retail prices for your pumpkins. However, you will have additional expenses for advertising, building and maintaining a facility and providing service to your customers. With U-pick operations, you save on harvest costs but you must be willing to have customers on your farm and have plenty of field supervision to instruct customers how and where to pick.
Farmers markets are another retail option, but market managers should be contacted well in advance of the marketing season to ensure space is available and to find out what requirements have to be followed.