The autumn season in temperate regions like the mainland is a time for the trees to shed their leaves before the coming winter. Autumn is the last growing season for most plants before chilling frost prevents further plant growth.
The change of seasons is not that drastic in Hawaii, yet we still see some of the effects of autumn, one of which is the arrival of pumpkins and winter squash in the supermarkets. Pumpkins and winter squash differ from summer squashes by producing a hard outer rind upon maturing; thus they can be stored for longer periods of time, especially during the winter.
Pumpkins are associated with Halloween jack-o’-lanterns in October and pumpkin pie for Thanksgiving in November. Pumpkin varieties mature in about 100 to 120 days, so seeds should be planted in July to allow them enough time to grow for Halloween.
Pumpkins belong to the plant family Cucurbitaceae, which includes summer and winter squashes, cucumber and melons. The genus Cucurbita originated in the New World between the southern temperate zone of North America and the northern temperate zone of South America. Different types of pumpkins have scientific names such as Cucurbita pepo, Cucurbita mixta, Cucurbita maxima and Cucurbita moschata.
The word "pumpkin" comes from the Greek word "pepon," meaning large melon. The French converted it to "popon" and then "pumpion." American colonists changed the "ion" to "kin" to make it "pumpkin."
The plants are vines that needs lots of space and a sunny location to grow. The vines produce large leaves that require lots of water yet adequate drainage to prevent root rot.
Pumpkins like loose, loamy to sandy soil with a pH range of 6.0 to 7.0. Organic matter incorporated into the soil helps to retain moisture and provides added nutrients. Home gardeners can incorporate a pre-plant fertilizer such as 1 pound of 16-16-16 analysis per 50 square feet.
The vines are monoecious, meaning there are separate male and female flowers on the same plant. The male flowers contain the pollen and emerge first, usually outnumbering the female flowers by a ratio of 12-to-1 or more. Female flowers must be pollinated usually by bees or by hand.
Popular varieties grown locally are the Japanese pumpkins or "kabocha" types, including Green Hokkaido and Orange Hokkaido. Several orange rind varieties are used for jack-o’-lantern carving and baking.
Pumpkins are sweet, high in vitamin A and can be baked, steamed, used in pies, breads and cakes. The giant pumpkin varieties include Atlantic Giant, Big Max and Big Moon.
Growers of giant pumpkins select one pumpkin to grow on a vine to allow the maximum amount of nutrients to be concentrated on that single pumpkin. The 2011 world’s record was a 1,818.5-pounder grown in Quebec.
The major insect pest is the melon fly, which lays eggs into the pumpkin while the outer rind is still soft. Other pests include pickleworms, aphids, whiteflies, thrips and sometimes rats.
The most common fungal disease is powdery mildew, which affects the leaves of the vines. Developing pumpkins can be covered with fine-meshed floating row covers to prevent insect damage, and careful watering to eliminate or reduce overhead watering helps prevent the spread of fungal spores onto the leaves.
For more information, contact the University of Hawaii Cooperative Extension Service.
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Richard H. Ebesu is the Kauai Master Gardener coordinator. To contact your local UH Master Gardener Program, visit www.ctahr.hawaii.edu/UHMG.
