This time of year, pumpkins can be seen all over the place. They are native to the Americas and related to the gourds, cucumbers and melons we all enjoy.
There are basically four species of what we consider to be “pumpkins” — Cucurbita pepo, C. maxima, C. moschata and C. argyrosperma. C. pepo includes what we use for traditional jack-o’-lanterns and pie, as well as all of the soft-skinned summer squashes. All have hard woody stems at maturity. In general, C. pepo is also the most disease and insect susceptible of the pumpkins.
C. maxima can get very large; prize-winning giant pumpkins come from this group. The largest pumpkin entered at the recent Hawaii Island pumpkin contest was a C. maxima grown in Waimea that weighed more than 600 pounds. They are characterized by spongy cork-like stems, a relatively well storage life, and include all of the winter squashes, such as buttercup and Hubbard varieties.
C. moschata are the best keepers in terms of storage and their flesh is often orange and sweet and has the most refined culinary qualities. They can be identified by their smooth, deeply ridged stems. Members include the butternut and cushaw.
C. argyrosperma normally have pale yellow to cream colored flesh. They are not very sweet and typically grown for their seeds. They have enlarged, hard corky stems.
To try your hand at growing your own pumpkins, here are some general pointers.
Pumpkins are heavy feeders and drinkers, and to grow the best fruits, a well-prepared bed is essential. First, find an area with full sunlight, good drainage and air movement. Dig a hole that is 24 inches deep and twice as wide. Add aged manure or compost, fertilizer with superphosphate and incorporate into the soil. Plant three to five seeds about 1 inch deep, and about 6 inches apart, and cover lightly with soil. Water the plants two or three times a week, but be mindful of the weather. Don’t over water. While the vines are becoming established, keep weeds under control by hand weeding, mulching and, possibly, using a weed mat. Pumpkins are generally ready to harvest three to four months after planting, but can take twice that long, depending on the variety.
Once seedlings have two or three leaves, you will want to thin them down to one or two plants per foot. Fertilize them every four to six weeks with 10-20-20 fertilizer. Pumpkins have male and female flowers on the same plant. Male flowers are the first to appear. These blossoms are great deep fried and even better stuffed. The female flowers are identified by the immature fruit directly beneath the flower. Hand pollination may be required in cases where pollinators are not present. This can be done by picking a blooming male flower and transferring pollen to the stigma of the female flower.
A common insect pest of pumpkins is the pickleworm, which likes to feed on blossoms as well as burrow into fruit and shoots. Using insect netting can help keep them out but will also prevent honeybees from getting in and pollinating. If you are going to hand pollinate the flowers, this won’t be an issue. A common disease of pumpkins is powdery mildew, which is a fungal disease that thrives in humid environments with little rainfall.
You may notice white fungal growth on the leaves, petioles and stem of the pumpkin. Avoid watering foliage to help minimize spread.
Determining when to harvest your pumpkin may be tricky. It may be time to harvest when you notice the skin lose its sheen, the tendrils die or when the fruit stem becomes woody. One rule of thumb is the fingernail test. When the fruit resists puncture by your thumbnail, it is ready to harvest. Make sure to leave the stem attached as this will prolong storage potential. An open stem scar can be an invitation to disease and insect infection. As convenient as it may appear, the stem is not the fruit’s handle. To increase the life of your pumpkins, place them in a curing area, with good ventilation and no direct sunlight, for a week to 10 days. Curing aids in the healing of wounds and toughening of the rind.
Now it’s up to you to decide what to do with your pumpkin — turn it into a jack-o’-lantern or pie, or use it as a decoration for trick-or-treaters or the Thanksgiving table. As a historical note, the pumpkin pie of the Pilgrims was more like pot pie. The top of the pumpkin was cut open and the seeds removed. The void was filled with fruit, spices, sugar and milk and with the top replaced, the pumpkin was baked on wood coals. Pumpkins are very nutritious and their bright orange flesh is full of beta carotene, a precursor to vitamin A. Pumpkins are also a good source of potassium and dietary fiber.
For recipes using pumpkin and other vegetables grown in Hawaii, visit ctahr.hawaii.edu/oc/freepubs/pdf/B-97.pdf. For more information on home gardening, visit ctahr.hawaii.edu/uhmg/EastHI/index.asp or any of Cooperative Extension offices islandwide.