Plant Common Name
This sprawling, warm-season annual vine originates from Mesoamerica, from Mexico to Costa Rica. Botanists believe the cushaw squash was first cultivated about 7,000 years ago in southern Mexico. Traditionally the flowers, stems and both immature and mature fruits were eaten. When compared to its close cousins, Cucurbita pepo and C. moschata, the fruits of C. argyrosperma are less flavorful and lower in quality for eating overall but they are decorative.
A diverse species with two natural subspecies, the firm skinned fruits come an array of sizes. Fruits are either globose or have a neck and bulbous end and are largely white with green speckles. Today, several modern winter squash, pumpkin or gourd cultivars are the result of hybridizing cushaw squash with other cucurbit species.
Two types of cushaws dominate gardens. Silver seed types are bitter and unpalatable and largly grown for their oil-rich seeds. In contrast, the callicarpa or cushaw types are grown for their tasty squash. All forms are visually appealing and attractive for decorative fall displays.
The rambling or climbing plants can grow quickly to a very large size and have many large, broadly oval to heart-shaped, green leaves. Each leaf is coarse, hairy and can irritate the skin if touched. Like most cucurbits, separate male and female flowers appear on the same plant. These blossoms are large, golden yellow to orange, trumpet-shaped and pollinated by bees. The male flowers open first on the vine, followed by the female flowers, distinguished by bulbous ovaries at their bases which develop into fruits following pollination.
Cushaw squash fruits tend to mature with hard rinds that are either smooth or slightly ridged. Rind color is naturally white or white with long green stripes or speckles. Cut the fruit open to see the internal white, yellow or orange flesh. A few types may be harvested when the fruits are immature and tender, but most are treated as winter squash, ripening in late summer to fall. Each fruit contains a cavity filled with numerous elliptical, inflated seeds with scalloped edges. These may be roasted and eaten, or dried and saved for the following year's garden.
Directly sow seeds of Cucurbita argyrosperma into mounds of rich, porous soil when the danger of frost has passed.
Warm, moist soil and a long growing season are needed for good growth and fruit development. Full sun is required. The fruits are typically ready for harvest from 90 to 120 days after sowing. To reduce the risk of fungal problems, avoid unnecessary wetting of vine stems and leaves. Monitor closely for stem borers (although this species seems to be naturally resistant to damage), leaf bugs and beetles. As fruits mature in autumn, deer, birds and rodents may browse them, so protect as needed. Mature cushaw squash fruits should be harvested before heavy frosts when their color is solid, the rinds firm, and the vines begin to brown and die back. Cut carefully from the vine, leaving a short stem for easy handling and to discourage fruit rot. Take care not to cut or bruise the skin, and store the fruit in a cool, dry, frost-free location.