Harvesting and Storing
Winter Squash and Pumpkins

This article by James E. Motes appeared in
“Hort[iculture] Tips,” May 1995, published by
Oklahoma State University Cooperative Extension Service.

Squash and pumpkins are still very much alive even after they have been removed from the vine. The objective of curing and storing is to prolong the life of the fruit by (1) slowing the rate of respiration, and (2) protecting against storage rots.

Rate of respiration is most effectively controlled by lowering the temperature of the fruit. For each 18-degree F drop in temperature, the respiration rate is cut in half. However, chilling injury can occur to some fruits stored below 50 degrees F.

Even though relative humidity (air moisture) has little effect on respiration, a relatively high rate (70 to 75 percent) is needed to protect against excessive shriveling. Relative humidity greater than 85 degrees F can enhance disease development.

When to Harvest.

Mature squash and pumpkins are more successfully stored than immature fruit. Butternut, Acorn, and Hubbard types have very hard skins, and will resist puncture by your thumbnail when they are mature. Additionally, as squash matures, the fresh, bright, juvenile surface sheen gives way to a dull, dry-appearing surface. Most of the orange colored pumpkins will have softer skin than those mentioned above, but will exhibit the same surface appearance alterations.

Dead vines are not necessarily an indication of maturity in squash and pumpkins, even though growth ceases when this occurs. When vines die prematurely, from disease, etc., their fruit are most likely immature and of low quality, and generally do not store as well as those grown on healthy vines.

Guard Against Injury.

Special care should be exercised to guard against scratches, cuts, or bruises to the fruits. Not only are they unsightly, they also provide an easy entrance for various rot-producing organisms. Rough surfaces in the handling path should be padded with old carpeting or similar material. Large fruit, like pumpkins, should not be stacked on top of each other. Do not store pumpkins, particularly large fruited types, on hard surfaces such as concrete. Padding material, such as grain straw, should be used liberally if fruits have to be stacked during harvest.

Storage Facilities.

Storage facilities should be equipped with accurate temperature and humidity controls. A fan to provide air circulation is also needed.

Except for Acorn types, which lose their quality during curing, evidence tends to support a 10-day curing period at a temperature of 80 to 85 degrees F and a relative humidity of 80 to 85 percent. After the curing period, lower the temperature to 50 to 55 degrees F and the relative humidity as indicated in the accompanying table.

When winter squash are taken out of storage, they should be marketed or consumed immediately to avoid excessive rot development. Black rot, dry rot, and bacterial soft rot are the principal causes of spoilage in stored winter squash.

Table. Ideal Storing Conditions For Winter Squash and Pumpkins
TYPE	APPROXIMATE LENGTH OF STORAGE	RELATIVE HUMIDITY	REMARKS
Pumpkins	2 - 3 months	50 - 75 %	Should be well matured. Don’t store with apples.
Hubbards	5 - 6 months	70 - 75 %	Hold very well in storage
Acorn	5 - 8 weeks	50 - 75 %	At temperatures over 55 degrees F surface will become yellow and flesh stringy
Butternut Buttercups	2 - 3 months	50 - 75 %	Degree of maturity not as important as for other types