It is time to plant pumpkins

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Last Updated: 
February 19, 2003

Pumpkins are actually a type of winter squash, with a hard rind. Seed companies offer all sizes and shapes of pumpkins, from the tiny Jack Be Little variety—which grows to only three to four inches—to the huge trophy-sized Atlantic Giant.

Pumpkins are a warm season crop, explained Ross Penhallegon, horticulture agent with the Oregon State University Extension Service. They usually need about two months of warm growing days with temperatures above 75 degrees to set and grow a plentiful yield. Most varieties need a lot of garden space, but small fruited varieties can be grown on a trellis. One or two plants will produce enough for a family of four.

Pumpkins should be planted after the danger of frost has passed and the soil is thoroughly warm. Pumpkins love fertile soil. Before planting spade the soil about a foot deep and mix in a well-balanced fertilizer. Then plant two or three seeds in a group about an inch apart in moist soil. Cover the seeds with a half inch of moist soil and firm it lightly over them, then place another half inch of soil loosely on top.

If you plant to grow more than one or two pumpkin vines, space groups of seeds four feet apart along the row. If the soil remains moist, do not water again until seedlings become well-established. Too much water will slow plant growth and encourage fungus diseases. When the plants have three leaves, remove the extra plants, leaving the strongest one in each group.

When the plants form runners, Penhallegon recommends giving them more fertilizer. For every 10 feet of row, scatter one to two cups of ammonium sulfate or other source of nitrogen such as manure, fish, or blood meal in the irrigation furrow. Rake it in lightly, then irrigate thoroughly. Keep moisture-robbing weeds under control.

Male and female flowers must bloom at the same time for pollination to occur. Early buds may drop off, but fruit will set from later female blossoms as long as bees are present to carry the pollen from the male flowers.

Harvest pumpkins using a sharp knife, when the stem becomes hard and woody, about three months after planting. Cut them off the vine leaving two inches of stem. Pumpkins will keep up to six months in a cool dry place.

Insect pests that occasionally attack pumpkin plants include aphids, mites, whiteflies, leafhoppers, and squash bugs. Since early pest detection and treatment result in better control, inspect your plants frequently.

Oregon seed companies that offer novelty and mainstay varieties of pumpkin seed include: Nichol's Garden Nursery, 1190 North Pacific Highway, Albany, OR 97321-4598 and Territorial Seed Company, P.O. Box 157, Cottage Grove, OR 97424-0061.

Author: Carol Savonen