Acorn squash, a variety of Cucurbita pepo, is classified as a winter squash despite its relatively quick maturity. Its firm, dark green skin and sweet, nutty flesh make it a popular addition to the late-season garden. A thorough understanding of the plant’s developmental cycle allows for timely intervention and proper care at each stage. Following the specific needs of the squash from planting to harvest ensures the highest yield of quality fruit.
Germination and Early Seedling Care
Acorn squash seeds can be started indoors several weeks before the final expected frost, or directly sown once the soil temperature is consistently warm. For successful germination, the soil temperature must be at least 60°F, as this warmth-loving crop struggles in cooler conditions. Seeds should be planted about one inch deep and covered loosely with soil to ensure good contact.
For direct sowing, planting seeds in hills is common, placing three to four seeds per hill. Hills should be spaced three to four feet apart to accommodate the sprawling vines. Seedlings emerge within six to twelve days, first showing their temporary cotyledon leaves. Once the first set of true, lobed leaves appears, thin the planting to only the strongest seedling per spot or hill. Removing the weaker plants prevents competition for light, water, and soil nutrients.
Vine Development and Flowering
After establishment, the acorn squash plant enters a period of rapid vegetative growth, sending out long, trailing vines that can spread several feet. The plant’s expansive nature requires consistent access to water, about one inch per week, to support the rapid production of leaves and stem tissue. While many varieties grow on the ground, some compact cultivars can be supported vertically on a sturdy trellis, which conserves garden space and keeps the fruit off the soil.
The onset of flowering is characterized by the appearance of bright yellow blossoms of two types: male and female. Male flowers, which are borne on thin stems, typically appear first and drop off after a day or two, serving primarily as a source of pollen. Female flowers are identifiable by the miniature, unpollinated ovary visible at the base of the flower where it meets the vine.
Successful fruit development relies on the transfer of pollen from a male flower to the stigma of a female flower, usually accomplished by bees. If natural pollinators are scarce, the grower can hand-pollinate by taking a male flower, removing the petals, and gently touching the anther to the center of the female flower. The plant continues to produce both types of flowers, but female flower production, which requires more energy, can be delayed if the plant is stressed by insufficient water or high nitrogen fertilizer.
Fruit Set and Maturation
Following successful pollination, the small ovary at the base of the female flower, which is botanically a fruit, immediately begins to swell. This marks the beginning of the fruit set stage, where the tiny, green squash starts its journey toward full maturity. The maturation phase is an extended period, typically lasting 50 to 60 days from fruit set until the squash is fully ripe.
During this time, the fruit changes from a pale green to a deep, dark green hue. Simultaneously, the thin, soft outer layer, or rind, begins to harden, a process necessary for the squash to be classified as a long-storing winter variety. The plant must maintain health throughout this phase, as a consistent supply of nutrients and water ensures the fruit develops its sugars and firm texture. Disruption can lead to premature ripening or a compromised rind that will not store well.
Knowing When and How to Harvest
Determining the precise moment for harvest involves recognizing several physical indicators that signal full maturity. The deep, dark green color of the skin should be uniform across the entire fruit, sometimes developing a slight orange blush or yellow spot where it rested. The rind should feel hard and firm to the touch, resisting indentation when pressed with a fingernail.
Another reliable sign of readiness is a dull, hollow sound when the squash is gently tapped, contrasting with the higher pitch of an unripe fruit. The stem connecting the squash to the vine should also begin to dry and harden. To harvest, use a sharp tool to cut the stem at least two to three inches above the fruit, leaving a generous piece attached. This small piece of stem, known as the “handle,” helps prevent moisture loss and seals the fruit from potential rot-causing pathogens during storage. A brief curing period of seven to ten days in a warm, dry location after harvest further hardens the skin, extending the squash’s shelf life.