Squash

History

Summer and winter squash are members of the Cucurbitaceae family, also known as the gourd family, which includes crops such as cucumber, cantaloupe, watermelon, and gourd (Figure 1).

The species Cucurbita pepo includes most summer squashes (Scallop, Yellow Crookneck, Yellow Straightneck, and Zucchini); winter squashes (Acorn, Delicata, and Spaghetti); and field and pie pumpkins and gourds. This is the most diverse species in the Cucurbitaceae family in terms of fruit appearance, size, and flesh color. The species Cucurbita maxima includes the largest-size squashes and pumpkins: fruits that generally store very well, like the Buttercup, Hubbard, and Kabocha. Cucurbita moschata includes squashes and pumpkins that also store well and are very flavorful, such as the winter squashes Butternut and Calabaza, along with specialty varieties like the Cushaw squash.

The name squash is derived from the Massachusetts Native Americans who named it “askutasquash,” which means “eaten raw or uncooked.” C. pepo and C. moschata are the earliest varieties, thought to have originated in Mexico and Central America about 9,000 years ago. Squash is essential to the native diet of these peoples, along with corn (maize) and beans. Hence, the traditional Native American or Indigenous peoples’ companion growing method called “Three Sisters” was born. In this growing method, pole beans were trellised on corn stalks while squash covered the ground to prevent weeds. These two species, C. pepo and C. moschata, were dispersed throughout North America by Indigenous peoples before the discovery of the New World. C. maxima is thought to have originated further south near the Andes Mountains in Argentina, Bolivia, and Chile, and was not spread as early as the other two species (the earliest documentation was in 1591). This species needed plentiful warm weather to grow and did not thrive in Europe. See Figure 2.

Historically, Native Americans planted this crop to cover the ground and prevent weeds beside corn and snap beans. The corn stalks serve as a natural support for snap bean plants. This native companion growing method is called “Three Sisters” (see Figure 3).

Squash remains an important vegetable in Southern cuisine as it grows well in warm climates. The Mirliton or Chayote squash originated in the Americas and is another member of the Cucurbitaceae family. This is an important crop for traditional diets across Mesoamerica and is very popular in Louisiana. The common name in this region, Mirliton, is the Creole-French translation of Chayote. Mirliton squash is still used in Creole cooking today, commonly stuffed with seafood or meat, and is a popular seasonal dish for the holidays.

Varieties

Squash is a warm season, frost-sensitive annual crop with many varieties ranging in color, shape, size, and taste. This crop can be divided into two main types (1) summer squash and (2) winter squash.

Summer squash are defined as fruits harvested in an immature stage before the rind becomes hard. Summer squash varieties are harvested and consumed fresh in the summer season and are mostly bush-type plants. The skin is tender and easily penetrable, and fruits are harvested young, normally only a few days or less than a week after pollination. Summer squash can be divided into four main types: (1) scallop or patty pan, (2) yellow crookneck, (3) yellow straightneck, and (4) zucchini (see Figure 4).

Scallop or patty pan squash have small, saucer-shaped fruit about 3-7 inches in diameter with scalloped edges. This type of summer squash tends to be very productive, with common skin colors of white, green, and yellow. Several varieties are recommended for Louisiana, including Benning’s Green Tint and Early White Bush (both of which are heirlooms) and a miniature variety named Peter Pan.

Yellow crookneck and straightneck squash can be differentiated by either a curved or straight fruit neck, respectively. Most varieties have smooth skin, but some crookneck varieties have bumpy skin. It is important to harvest yellow summer squash when they are tender, as they may quickly develop a tough texture and seeds that are mature and more pronounced (but still edible). Heirloom varieties include Early Summer, Dixie, and Early Prolific.

Zucchini squash are generally very productive and produce larger fruit with green skin, although several yellow-skinned varieties such as Gold Rush and Sebring are recommended for Louisiana. Heirloom varieties include the Italian Cocozelle and Costata Romanesco, along with the Mexican Tatume.

Winter squash are physiologically mature fruit with a hard rind that cannot be penetrated with a fingernail, containing visible seeds at harvest.  Despite the name, winter squash varieties are also grown and harvested during the summer season, and then cured and consumed throughout the winter season. This type has mostly vining habits, but bush-types are available. Winter squash include many types recommended for Louisiana: (1) acorn, (2) buttercup, (3) butternut, (4) calabaza, (5) delicata, (6) Hubbard, (7) kabocha, (8) spaghetti, and (9) specialty (see Figure 5).

Acorn (round, mostly dark green) and delicata (cylindrical, yellow or cream with green stripes) squashes are smaller, ribbed fruits. Butternut squash are high-quality, bell-shaped fruit with tan-colored skin and flavorful dark orange flesh. Fewer buttercup, calabaza, and Hubbard squash varieties are recommended for Louisiana. Buttercup squash produce smaller, high-quality, green-skinned fruit; calabaza squash produce medium-large, round, ridged fruit in a range of colors; and Hubbard squash produce large orange, green, or gray oval-shaped fruit. Kabocha squash, a Japanese variety, is similar to buttercup squash with globe-shaped, green- or orange-skinned fruit. Spaghetti squash is a popular pasta substitute, as the flesh separates easily from the skin and may be cooked and used like spaghetti. It is medium-large, and oval-shaped, with yellow skin. Specialty squash, like the Caribbean heirloom Cushaw Green Striped, is also recommended for Louisiana.

Squash have either open-pollinated (including heirloom) or hybrid varieties. Seeds from heirloom varieties have been saved for at least 50 years, can be saved each season and replanted, and are open-pollinated. Squash have male and female flowers on the same plant (monoecious) that are only open for a single day and require multiple insect visits to produce a full, well-developed fruit. If saving seed, different varieties need to be separated by a distance of 800 feet-1/2 mile to prevent cross-pollination. Generally, it is not recommended to save seed for future planting with hybrid varieties as they are usually not expressed properly in the next generation.

Pumpkins are also a type of winter squash, but are more difficult to grow in Louisiana due to the hot and humid climate, which causes high pest and disease pressure. Normally pumpkins are planted in the early summer (late June, early July) in order to be harvested and ready for Halloween and the fall season. While they won’t be covered in detail in this guide, some recommended pumpkin varieties for Louisiana include: Aladdin, Appalachian, Aspen, Atlantic Giant, Autumn Gold, Baby Bear, Baby Boo, Big Autumn, Big Max, Big Moon, Casper, Charisma, Cinderella, Connecticut Field, Darling, Early Abundance, Frosty, Gold Medal, Gold Rush, Gooligan, Howden, Jack-Be-Little, Jack-O-Lantern, Jumpin Jack, Munchkin, Orange Smoothie, Peek a Boo, Prankster, Prize Winner, Silver Moon, Small Sugar, Sunlight, Sorcerer, Spirit, Spookie, Spooktacular, Trick or Treat, and Triple Treat.

It is recommended to select disease-resistant varieties whenever possible. See the recommended summer and winter squash varieties for Louisiana in Table 1.

Table 1. Recommended Squash Varieties for Louisiana

When and How to Plant

Squash should be direct seeded outside during the recommended planting dates based on summer or winter type (refer to the Squash Planting Guide, Table 2). As warm season crops, squash seeds germinate best in soil temperatures between 70-95 degrees F (optimum of 85-95 degrees F; minimum of 60 degrees F). There should be no danger of frost. The use of a soil temperature map can help guide planting decisions. For fall plantings, be sure to plant selected varieties with enough time to mature before the first frost date for the region (mid-November for North LA, late November for South LA, or mid-December for New Orleans).

Refer to the Squash Planting Guide, Table 2 for the recommended spacing based on summer or winter squash and growth type (bush, semi-bush, or vining) when planting seeds outside. Sow seeds 1 inch deep, cover with soil, and water in. Seeds should emerge in about 5-7 days.

Alternatively, bush varieties of summer and winter squash may be planted in 12-inch hills of 3-4 plants following the same spacing recommendations. Sow 5-6 seeds in a small circle, and thin to 3 seedlings once a few true leaves develop. Here is a video showing how to plant seeds using the hill method.

Table 2. SQUASH PLANTING GUIDE

Where to Plant

Squash is a warm season crop; well-draining, loose soil, and full sun (6 hours/day) are recommended. Squash plants prefer a soil pH between 6.0 and 6.8 but will tolerate a pH as low as 5.5 or as high as 7.7. It is recommended to plant squash in box beds or in traditional raised garden rows that are about 12 inches tall to ensure good drainage and to prevent disease. In all types of gardens, it is recommended to add a 2- to 3-inch layer of compost, peat, rotted hay, or other organic matter and mix into the soil to optimize plant health. This is especially important for squash plants, which thrive in soils high in organic matter and nitrogen. Fish emulsion fertilizer may be used if leaves are yellowing.

Plastic mulch — or a plastic fabric/film — is recommended to increase soil temperature, yield, fruit size and quality, while controlling weeds and conserving moisture. Mulching will also help to deter common squash pests like cucumber beetles.

Floating fabric row covers are also recommended for this crop to improve growth and deter pests during the seedling stage. Row covers should be removed when plants enter the flowering stage of growth to optimize pollination. Do not use row covers if cucurbits were previously planted in the same area, as squash vine borers overwinter in the soil and may be trapped under the covers.

Each season, rotate plant families — avoid planting crops from the same plant family in the same area of the garden — to reduce disease and pests. A longer crop rotation is recommended for Cucurbitaceae crops to reduce pest pressure and risk of disease.

Plant Care

Watering

Squash plants should be watered enough to avoid plant wilt, as this may cause blossom drop. If the weather is dry, watering once or twice a week should be adequate, being especially sure that water demands are met during the fruit development stage. Adjust the watering schedule based on soil type: more frequently for sandy soils and less often for clay soils. Deep watering is important to strengthen the root system. Avoid wetting the plant foliage. Summer squash plants require more irrigation than winter squash.

Fertilization

Do not overfertilize squash with nitrogen. Excessive nitrogen may cause vining crops like squash to remain in a juvenile state and delay flowering and fruiting. Uneven watering may result in blossom-end rot of summer squash, a disorder resulting from calcium deficiency. Inconsistent watering causes calcium to be poorly dissolved in the soil and unavailable for uptake. If blossom-end rot persists with even watering, conduct a soil test and discuss results with a local county extension agent.

Organic fertilizers such as compost, fish emulsion, composted poultry litter or manure, worm castings, and blood or bone meal originate from living organisms. They are far more environmentally sustainable and safe than traditional synthetic fertilizers. They naturally release nutrients more slowly and over a longer period of time. When applying organic fertilizer, it is important to use in unison with compost, cover crops, and crop rotation, which all work together to build soil health. Learn how to convert inorganic fertilizer recommendations to organic fertilizers here.

Alternatively, a synthetic fertilizer may be used at a rate of about 1 pound (2 cups) of 13-13-13 for every 25 feet of row or 75 square feet. Broadcast, or sprinkle evenly, over the soil and then mix in about 3-6 inches deep using a rake. Supplemental sidedressing, or reapplication of synthetic fertilizer, is recommended when plants begin to run (change to a vining habit). Sidedressing is the addition of fertilizer to the soil around already established plants when the plant begins to fruit or vine, primarily to provide nitrogen. When using synthetic fertilizer, sprinkle 2 tablespoons around each plant, keeping it about 6 inches away from the plant stem; water into the soil. Additional sidedressing may be applied every 3-4 weeks. Because of their slow, steady release of nitrogen, crops fertilized with organic fertilizer do not usually need to be side dressed. Fish emulsion provides a quick-release, organic form of nitrogen, if needed.

Weeds

Plastic mulch will control most of the weeds; hand-pull weeds close to the plant, especially in the planting holes. If using tools to weed, avoid hoeing deeper than 1 inch so as not to damage shallow roots.

Insect Pests and Diseases

Aphids are common insect pests for squash plants and can transmit harmful viruses. Other common squash insect pests include cucumber beetles, spider mites, squash bugs, and squash vine borers. Squash plants are susceptible to aphid-vectored viruses (e.g., cucumber, watermelon, and zucchini yellow mosaic viruses and papaya ringspot virus), fungal diseases (e.g., anthracnose, downy and powdery mildew), and physiological disorders (e.g., blossom-end rot). Some squash varieties are resistant to specific diseases and these should be selected and planted — especially if the garden has been afflicted by one or more diseases in previous growing seasons. Generally recommended tools for prevention are using reflective mulches; avoiding overhead irrigation; improving air circulation; and crop rotation. See Table 3 to aid in diagnosis and management of some common squash insect pests and diseases.

Table 3. ORGANIC AND NATURAL MANAGEMENT FOR COMMON SQUASH INSECT PESTS AND DISEASES

Harvest and Storage

Summer squash fruit should be harvested when the fruit is young and tender. Most varieties should be harvested when the fruit is glossy and between 4-8 inches long. It is recommended to clip the fruit with shears, leaving a small, 1-inch stem attached (avoid twisting/breaking the stems). Use gloves when harvesting summer squash as most plants have small spines. Consistent harvesting and removal of overmatured fruit is essential for optimal production length; aim to harvest 2-3 times per week. The fruit is bruised easily and should be handled with care postharvest. Summer squash should be stored between 41-50 degrees F (95% humidity) for 1-2 weeks.

Summer squash blossoms may also be harvested in the morning when fully open. Clip flowers 1-2 inches below the base. Harvest only male flowers (identified by thin stems) if fruiting is desired, but make sure to leave some for pollination of female flowers. Harvesting female flowers (identified by thick stems with immature fruit at the base) comes at the expense of fruit production. See Figure 6 for a comparison of male and female squash flowers. Squash blossoms are considered a delicacy and are commonly prepared stuffed and fried. They are very popular in the Mediterranean area and in Mexican cuisine, as well as in farm to table restaurants in the U.S.

For winter squash, harvest fruit when they are full-sized and the skin is richly colored and hardened (should not be easily dented by a fingernail). Often the stems have begun to dry, and the plant itself has begun to wilt and brown. For some winter squash varieties like Acorn, the bottom of the fruit touching the ground changes color from yellow to cream or gold to orange. It is recommended to clip the fruit using shears, leaving at least a 2-inch stem attached (avoid twisting/breaking the stems). Here is a helpful video on when and how to harvest winter squash. Use care in handling fruit to prevent wounds that may lead to decay and rot in storage.  Use clean and sterilized containers for curing and storage. After harvesting, most winter squash require a curing process in a warm area (80-85 degrees F with 75-80% humidity) for 10 days. After curing, fruits will keep for several months (depending on variety) if stored at around 50-55 degrees F (50-70% humidity). Take care not to store below 50 degrees F as this may damage the fruit.

Preserve squash by freezing or drying.

Squash are Nutritious and Good for You

Rich in Vitamin A

Important for eye health, a strong immune system, and cell growth

High in Potassium

Essential for body function, especially the heart, kidney, nerves, bones, and muscles

Contains Vitamin C

Important for bones, skin, blood vessels

Excellent source of dietary fiber

Important for bowel health, lowering cholesterol, controlling blood sugar, and maintaining a healthy weight

Recipes

Louisiana Harvest of the Month: Zucchini Pizza Boats

Common methods of preparing and cooking summer squash and winter squash

Videos on how to prepare summer squash, acorn squash, and butternut squash

Taste-testing ideas:

• Summer Squash: baked zucchini fries or chips, minestrone soup, ratatouille, zucchini pizza boats, sautéed or grilled squash, summer squash and pasta salad, vegetable chili, three sisters salad, zucchini bread
• Winter Squash: Autumn squash soup, roasted squash, butternut squash and black beans, baked acorn squash with honey and apples, spaghetti squash pasta, roasted seeds

Other websites with many squash recipes:

USDA MyPlate Kitchen: Summer Squash and Winter Squash

Food Hero: Summer Squash and Winter Squash

SNAP-Ed San Francisco: Summer Squash and Winter Squash

Produce for Better Health Foundation

Sources

• Southeastern Vegetable Extension Workers, 2020 Southeastern U.S. Vegetable Crop Handbook
• LSU AgCenter, Louisiana Vegetable Planting Guide
• LSU AgCenter, Louisiana Commercial Vegetable Production Recommendations
• LSU AgCenter, Vegetable Gardening Tips: Squash and Pumpkins
• UF Extension, Planting Guide
• UF Extension, Vegetable Production Handbook of Florida
• Texas A&M AgriLife Extension, Vegetable Varieties for Central Texas
• Texas A&M AgriLife Extension, Easy Gardening: Squash
• Texas A&M AgriLife Extension, Commercial Crop Guides: Squash
• Texas A&M AgriLife Extension, Aggie Horticulture: Squash Named from an Indian Word
• University of Minnesota Extension, Viruses of cucurbits
• UMass Extension Vegetable Program: Disease, Insect, and Mites Fact Sheets
• Alabama A&M & Auburn Universities Extension, Crop Production,
• Purdue Extension FoodLink: Summer Squash
• Purdue Extension FoodLink: Winter Squash
• Branley, Edward. (2015) NOLA History: Mirlitons. Go NOLA.
• Maynard, Donald N & Hochmuth, George J (2007). Knott’s Handbook for Vegetable Growers (5th edition). John Wiley & Sons, Inc.
• Decoteau, Dennis R (2000). Vegetable Crops. Prentice-Hall, Inc.
• Swiader, John M & Ware, George W (2002). Producing Vegetable Crops (5th edition). Interstate Publishers, Inc.
• Sukprakarn, S, Juntakool, S, Huang, R, and Kalb, T (2005). Saving your own vegetable seeds—a guide for farmers. AVRDC publication number 05-647. AVRDC—The World Vegetable Center, Shanhua, Taiwan. 25 pp.
• Seed Savers Exchange, Seed Saving: A Guide to Isolation Distances
• University of Georgia Extension, How to Convert an Inorganic Fertilizer Recommendation to an Organic One, Circular 853