Family: Cucurbitaceae
Genus and Species: Cucurbita pepo
Climate
Pumpkins are a warm season crop that need good soil, a lot of sun, and plenty of room to grow. Pumpkins are frost sensitive, but fast growing so they do well even in short growing season areas.
Soil
Pumpkins need fertile, aerated soil that is warm enough for germination (70°-90°) and warm enough for growing (65°-75°). Mix compost or well-rotted manure into the bed to ensure plenty of nutrients. Pumpkins grow best in soils with a pH between 5.5 and 6.5. Pumpkins need moderate amounts of potassium and phosphorus and high amounts of nitrogen.
Spacing
Grow pumpkins in a corner of the garden and train the vines to grow outside of the garden. Pumpkin vines are huge and they can take up most of your garden if you are not careful. Space plants 12"-18" apart.
If growing pumpkins in a row, space the pumpkin plants at 18" in rows 6' apart.
Alternately you can grow pumpkins on a hill of soil, compost or manure. When pumpkins are grown in hills make sure there is approximately 50-100 square feet of space per hill for the pumpkin vines to grow. Pumpkin hills should be approx 3' by 3'. Planting pumpkins on hills of rich soil or organic matter helps ensure these heavy feeders get what they need.
Direct Seeding
Direct seeding pumpkins is not recommended in areas with short growing seasons. Pumpkins need at least three months of frost free, warm to hot weather. If you live in a cool climate, start pumpkins indoors.
In areas with longer growing seasons, direct seed pumpkins once the danger of frost is past and soil temperatures are between 70° and 90°. Use black plastic to warm the soil if needed. Sow 2-3 seeds, 1" deep every 12"-18" in rows 6' apart. Thin to one or two pumpkin plants.
Alternately sow 4 to 5 seeds per hill.
Seeding For Transplants
In cool climates start pumpkin seeds indoors one month before the last frost. Sow pumpkin seeds in peat pots as pumpkins do not really like being transplanted. Sow pumpkin seeds 3 per pot and then thin to one plant per pot once pumpkin seedlings are established.
Germination
These seeds germinate best in soils around 70°F and 95°F.
Germination will take 6-10 days.
Transplanting Into the Garden
Transplant pumpkin starts when the soil is warm enough - approximately 70°-90°. Use black plastic to warm the soil. Put pumpkin seedlings with their peat pots into moist, warm soil and water thoroughly.
Watering
Pumpkins need to be watered regularly throughout the growing season. Keep the pumpkins evenly moist and water deeply during dry spells. To prevent mildew, water pumpkin plants at their base, don't water the pumpkin foliage. Watering the pumpkins in the early morning also helps prevent mildew.
Harvesting
Pumpkins are mature when the stems connecting the pumpkin to the vine begin to shrivel. Pumpkins can be harvested whenever they are a deep, solid color (orange for most varieties) and the pumpkin rind is hard. If the pumpkin vines remain healthy, harvest in late September or early October, before heavy frosts.
Harvest pumpkins before the first hard frost. Cut pumpkins from the vines carefully, using pruning shears or a sharp knife and leave 3" to 4" of stem attached. Snapping the stems from the vines results in many broken or missing "handles." Pumpkins without stems usually do not keep well. Wear gloves when harvesting pumpkins because many varieties have sharp prickles on their stems.
Post-Harvest Handling
Wash and dry pumpkins thoroughly. Avoid cutting and bruising the pumpkins when handling them. Pumpkins that are not fully mature or that have been injured or subjected to heavy frost will not store very well.
Storage
Pumpkins can be stored for several weeks in a root cellar but they do not keep as well as other squash varieties. Pumpkins will keep for 2-3 months in temperatures from 50° to 55° and 50%-75% relative humidity. Cure the pumpkins for several days in sunlight before storing them. Bring the pumpkins in at night if there is a frost predicted.
Diseases
Anthracnose, Bacterial Wilt, and Downy Mildew.
Pests
Cucumber Beetles and Squash Vine Borers.
Comments
To grow giant pumpkins use one of the jumbo varieties. Plant the pumkins in early June and allow 150 square feet per hill. Thin the pumkin plants to one or two of the best plants. High fertility, proper insect control and shallow cultivation are essential. Remove the first two or three female flowers after the pumkin plants start to bloom so that the plants grow larger with more leaf surface before setting fruit. Allow a single pumpkin to develop and pick off all female flowers that develop after this pumpkin has set on the plant. Do not allow the vine to root down at the joints near this developing pumpkin because these varieties develop so quickly and so large that they may actually break away from the vine as they expand on a pumpkin vine anchored to the ground.
References
Bradley, F. M. and Ellis, B. W.(Ed.). (1992), Rodale's All-New Encyclopedia of Organic Gardening: The Indispensable Resource for Every Gardener, Emmaus, Pennsylvania: Rodale Press.
Oregon State University, Pumpkin , Commercial Vegetable Production Guides, Last modified 1999-01-02, http://www.oregonstate.edu/Dept/NWREC/pumpkin.html, Accessed 2003-05-21
University of Illinois Extension, Growing Pumpkins, http://www.urbanext.uiuc.edu/pumpkins/growing.html, Accessed 2003-07-09
Smith, E.C. (2000), The vegetable gardener's bible: discover Ed's high yield W-O-R-D system for all North American gardening regions., Storey Books: Pownal, VT.