The months of March and April, sometimes referred to as the hungry gap, may be a lean time of year for gardeners. However, it need not be. For connoisseurs of squash, there are many types that store well even into early spring months.
As you begin to plan your gardens for this year, consider the storage qualities of squash. The optimal storage period for squash varieties can be significantly different. Not only do some keep longer, but the flavor of many varieties improves with storage. The evaluation team at Seed Savers Exchange evaluates squash for this very purpose.
Squash are typically classified into three different types, representing each of the three most commonly cultivated species. These are acorn (Cucurbita pepo), butternut (C. moschata), and buttercup (C. maxima). Within a species, varieties tend to have similar storage qualities, though there can be significant differences.
Acorn squash usually have the shortest storage life, with excellent flavor immediately after harvest and optimal eating qualities after only a few weeks of storage. Beyond 1-2 months in storage, its flavor and texture begin to decline.
Butternut squash required a longer period of storage to develop satisfactory flavor. Optimal eating qualities are attained after 30 days of storage and last up to 6 months in some cases.
Buttercup squash generally have good eating qualities at harvest, but like butternuts, improve after a month or two in storage and retain good flavor for up to 4-6 months under ideal storage conditions.
The storage quality of squash depends upon many factors besides genetics. Maturity of fruit at harvest, curing, and storage conditions all affect eating qualities and length of storage time. Almost all squash benefit from undergoing a curing process immediately after storage, except acorn types.
The curing process helps heal cuts and scratches and form a protective corky layer over injuries and the cut surface of the stem. Squash should be cured for 1-2 weeks at warm temperatures up to 85°F. Acorn squash should not be cured, as they can become stringy if exposed to warm temperatures. Once cured, store squash at 50-55°F and 50-70% relative humidity.
In our annual squash taste evaluation at Seed Savers Exchange, staff scored the eating qualities of 16 varieties on a scale of 1-5. Some varieties from the catalog that are delicious immediately after harvest include Table Queen, Thelma Sanders, Winter Luxury pumpkin, and Sweet Fall. Great choices for storage are Silver Bell, Sibley, and the old standard, Waltham Butternut. Available through the exchange are Lakota and Blue Ballet, two excellent keepers and very flavorful varieties.
As you flip through seed catalogs trying to decide which squash to grow this season, consider their storage qualities. By selecting several varieties that come into their prime at different storage times, you can ensure a continuous supply of delicious squash throughout the fall, winter, and into early spring!
Squash undergo physiological changes to sugar and starch content during storage that affect flavor and texture. Sugar not only gives a desirable, sweet flavor, but also masks off-flavors associated with certain varieties. Sugar content can be measured using a device called a refractometer, which gives a reading called degrees Brix. Brix is a measure of dissolved sugar in a liquid solution. The higher the BRIX score, the more sugar exists.
Starch, which gives squash a pasty texture, constitutes about two-thirds of dry matter content, or the solids that remain after water has been removed. Dry matter content can easily be measured using a dehydrator by taking before and after weights of a 15 g sample dried for 24 hours. We measured the sugar content and dry matter content of squash for the first time in 2015 both before and during storage.
Together, sugar and starch comprise between 50-70% of the dry biomass of squash flesh with the ratio of each changing in tandem as starch converts to sugar over time. Each has minimum levels for optimal flavor and texture. Squash with dry matter content above 18% and a BRIX score over 11% are considered good eating varieties (Loy and Noseworthy, 2009).
Because starch content and sugar levels change during storage, the optimal time of consumption for squash varieties differs based on the starch and sugar levels at harvest. For example, butternut and buttercup squash require a month or two in storage in order for starch to convert to sugar, and thus making them sweeter. Acorn squash, however, are recommended for immediate consumption because they have sufficient sugar levels at harvest. In addition, their relatively low starch content at harvest means that the texture will degrade fairly quickly.
In our annual squash taste evaluation at Seed Savers Exchange, staff scored the eating qualities of 16 varieties on a scale of 1-5. With the varieties arranged from worst to best, there was a trend between preference, starch content, and sugar content. The top five varieties had dry matter contents ranging from 14-21% and Brix scores of 10-13%. The five least favorite varieties had dry matter contents ranging from 8-17% and Brix scores 6-9%. But remember, taste is subjective.
Silver Bell, a small Hubbard-type, with 21%DM and 12% Brix finished slightly behind Spookie, a pie pumpkin, with 6% Brix and 6%DM. These anomalies may be the result of other constituents affecting flavor and texture or the taste preferences of staff members! It is interesting to note that in our taste trails after 4 months storage, Silver Bell was the favorite.
Seed Savers Exchange is a nonprofit organization located in Decorah, Iowa, with a mission to conserve and promote America's culturally diverse but endangered garden and food crop heritage for future generations by collecting, growing, and sharing heirloom seeds and plants.