Washington State University Extension

Garden Tips


written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA
published- OCTOBER 3, 2014


Ever wonder what’s the deal with giant pumpkins? This year the first place pumpkin at the Washington State Fair in Puyallup weighed in at 1609.5 lb and was grown by Stan Pugh of Puyallup. Purists might argue that these are not really pumpkins but a type of winter squash. I tend to agree, but the term “pumpkin” is subjective.

The pumpkins that folks typically make into jack-o-lanterns have smooth orange skin. The fruit is somewhat ribbed and the stems are furrowed and woody. Botanically they are members of the genus Cucurbita and the species pepo. Cultivated varieties (cultivars) of what I think of as pumpkins are a subgroup of Cucurbita pepo. Other subgroups of Cucurbita pepo include summer squash, acorn, spaghetti, delicata, and ornamental gourds.

The gargantuan giant “pumpkins” grown for fairs and festivals around the country are a subgroup of a different genus, Cucurbita maxima. They tend to have orange or orangish skin with ribbed fruit. Their stems are spongy without ribs. Other true winter squash in Cucurbita maxima include blue Hubbard, banana, buttercup, turban, delicious, and Kabocha squash cultivars.

Yet another species of winter squash, Cucurbita moshata, has some cultivars dubbed “pumpkins.” Generally, C. moshata pumpkins have deeply ridged stems that flare out at their base. The skin may be orange, buff, or green, and the flesh is dark orange and dry. These are type used for making canned pumpkin and pumkin pie. Butternut squash are in a different subgroup of C. Moshata.

Carved Pumpkins: Every fall my children and grandchildren delight in carving pumpkins, the type I call real pumpkins. They go to a lot of work digging out the gooey guts and deciding on carving designs. After all that work, it seems a shame that the pumpkins start to shrivel and mold within a few days and are usually goners a week after carving. I researched credible recommendations regarding how to prolong the life of carved jack-o-lanterns.

Parden the pun, but once pumpkins are cut they are “ripe” for rot. The cut surfaces allow easy entry to molds and rot fungi into the flesh. One simple step in preserving pumpkins is placing placing the carved pumpkins where they will stay cool and out of direct sunlight during the day. Dedicated carvers recommend store prized specimens in the refrigerator to slow down the decay process. Carvers also recommend against placing your pumpkins directly on concrete as this will draw moisture out and lead to quicker shriveling due to moisture loss.

An Illinois Extension educator suggests dunking or spraying the cut surfaces with a 20% bleach solution and blotting it all dry. However she did not offer any proof that it works, so I am skeptical of that approach.

There is also a product available on-line called Pumpkin Fresh containing a borax solution and they indicate it “preserves and protects” and “fights mold and rot.” It is sprayed on the inside and cut surfaces daily to discourage fungi. I find the results of a school science project where a student tested both bleach and Pumpkin Fresh against the control. The “winners” in overall longevity were the control and the Pumpkin Fresh but one had more mold and the other more rot and both were pretty shriveled after two weeks.

I might get some and give it a try this year. Of course that means carving two pumpkins, one to be used as a control. I’ll let you know if it works.

Published: 10/3/2014 12:13 PM

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