Pumpkin is a warm-season vegetable that can be grown throughout much of the United States. Besides being used as jack-o'-lanterns at Halloween, pumpkins are used to make pumpkin butter, pies, custard, bread, cookies and soup.
Pumpkin is a very tender vegetable. The seeds do not germinate in cold soil, and the seedlings are injured by frost. Do not plant until all danger of frost has passed, and the soil has thoroughly warmed. Plant pumpkins for Halloween from late May in northern locations to early July in extremely southern sites. If pumpkins are planted too early, they may soften and rot before Halloween.
Vining pumpkins require a minimum of 50 to 100 square feet per hill. Plant seeds one inch deep (four or five seeds per hill). Allow 5 to 6 feet between hills, spaced in rows 10 to 15 feet apart. When the young plants are well-established, thin each hill to the best two or three plants.
Plant semi-bush varieties one inch deep (four or five seeds per hill) and thin to the best two plants per hill. Allow 4 feet between hills and 8 feet between rows.
Plant miniature varieties one inch deep, with two or three seeds every 2 feet in the row. Rows should be 6 to 8 feet apart, with seedlings thinned to the best plant every 2 feet when they have their first true leaves.
Plant bush varieties one inch deep (1 or 2 seeds per foot of row) and thin to a single plant every 3 feet. Allow 4 to 6 feet between rows.
Pumpkin plants should be kept free from weeds by hoeing and shallow cultivation. Irrigate if an extended dry period occurs in early summer. Pumpkins tolerate short periods of hot, dry weather pretty well.
Bees, that are necessary for pollinating squash and pumpkins, may be killed by insecticides. When insecticides are used, they should be applied only in late afternoon or early evening when the blossoms have closed for the day and bees are no longer visiting the blossoms. As new blossoms open each day and bees land only inside the open blossoms, these pollinating insects should be safe from contact with any potentially deadly sprays.
Pumpkins can be harvested whenever they are a deep, solid color (orange for most varieties) and the rind is hard. If vines remain healthy, harvest in late September or early October, before heavy frosts. If vines die prematurely from disease or other causes, harvest the mature fruit and store them in a moderately warm, dry place until Halloween. Cut pumpkins from the vines carefully, using pruning shears or a sharp knife and leave 3 to 4 inches 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 fruit because many varieties have sharp prickles on their stems.
Avoid cutting and bruising the pumpkins when handling them. Fruits that are not fully mature or that have been injured or subjected to heavy frost do not keep. Store in a dry building where the temperature is between 50 and 55°F.
Powdery mildew causes a white, powdery mold growth on the upper surfaces of the leaves. The growth can kill the leaves prematurely and interfere with proper ripening.
Cucumber beetles and squash bugs attack seedlings, vines and both immature and mature fruits. Be alert for an infestation of cucumber beetles and squash bugs, as populations build in late summer, because these insects can damage the mature fruits, marring their appearance and making them less likely to keep properly.
Q. The first flowers that appeared on my pumpkin plants did not form fruits. Why not?
A. This condition is natural for cucurbits (such as cucumber, gourd, muskmelon, pumpkin, squash and watermelon). The first flowers are almost always male. The pollen on these first male flowers attracts bees and alerts them to the location of the blooming vines. By the time the first female blossoms open, the bees' route is well established and the male flowers' pollen is transferred to the female flowers by the bees. Male flowers bloom for one day, then drop off the plants. The male flowers may predominate under certain conditions, especially early in the season, or under certain kinds of stress. The small fruits, visible at the bases of the female flowers, identify them. There is no swelling on the bases of the male flower stems.
Q. How can I grow pumpkins that weigh more than 100 pounds?
A. Use one of the jumbo varieties. Plant in early June and allow 150 square feet per hill. Thin to the best one or two plants. High fertility, proper insect control and shallow cultivation are essential. Remove the first two or three female flowers after the plants start to bloom so that the plants grow larger with more leaf surface before setting fruit. Allow a single fruit to develop and pick off all female flowers that develop after this fruit has set on the plant. Do not allow the vine to root down at the joints near this developing fruit because these varieties develop so quickly and so large that they may actually break from the vine as they expand on a vine anchored to the ground.
Q. My grandmother made pies with a green-striped, long-necked pumpkin. Is this variety still available?
A. Yes. The variety is Green-Striped Cushaw. Because it has a unique texture, some cooks prefer it for custards and pies.
Q. Will pumpkins, squash and gourds cross-pollinate and produce freak fruit if I interplant several kinds in my garden?
A. Pumpkins, squash and gourds are members of the vine crops called "cucurbits." The name is derived from their botanical genus classification of Cucurbita (often abbreviated C.). There are four main species of Cucurbita usually included in the pumpkin, squash and gourd grouping. The varieties within a botanical species (which may be referred to as pumpkins, squash or gourd) can cross-pollinate. Varieties from different species do not. For example, zucchini crosses with Howden's Field pumpkin, acorn or spaghetti squash, small decorative gourds, or Jack-Be-Little miniature pumpkins because they are all members of the same botanical species (C. Pepo).
However, cross-pollination does not affect the taste, shape or color of the current season's fruit. Crosses show up only if seeds from these fruits are saved and grown the following year. Butternut squash, Small Sugar pumpkin, White Cushaw pumpkin, and Big Max pumpkin could all be grown in the same area without crossing because each variety comes from a different species. Because bees carry pollen for distances of a mile or more, in suburban areas where many gardens are in close proximity, fruits must be bagged and pollinated by hand if pure seed of non-hybrid varieties is desired.
Q. What is the difference between a pumpkin and a squash?
A. It is all in what you call it. Varieties of each of the four species, discussed in this section are popularly called "pumpkins," and varieties of each are called "squash," more by tradition than by system. In fact, orange color sometimes helps determine what is a pumpkin. Two varieties of the same species, C. maxima, hold the records for the world's largest squash and pumpkin. The variety called squash is gray to green and larger one called a pumpkin is pinkish to orange. Shape may vary slightly, but these two freely inter-pollinate and are botanically pretty much identical. Unless you are dealing with specific rules or regulations at a show, you can pretty much interchange the words squash and pumpkin, though you can expect a fight with purists, no matter what you do.