How to Grow and Care for Crookneck Squash (Yellow Squash)

Enjoy delicious, fast-growing crookneck squash all summer

yellow squash plant

Smartstock / Getty Images

Crookneck squash, named for the slight curves in their necks, are easy to grow in the vegetable garden. This cultivar of Cucurbita pepo, a type of summer squash, is also called yellow squash. The warm-season plants grow fast and have huge leaves with small, sticky spines and a bushy growth habit. Their yellow fruits, which form underneath the leaves, can have smooth or bumpy skins. For the best taste, pick them when they’re small and tender. The plants are so prolific, one or two are usually enough to feed a family.

Botanical Name Cucurbita pepo
Common Name Summer squash, yellow squash
Plant Type Vegetable, annual
Mature Size 2-3 ft. tall, 1-1 ½ ft. wide
Sun Exposure Full sun
Soil Type Loamy, well-drained
Soil pH Neutral to Acidic
Bloom Time Summer
Flower Color Yellow
Hardiness Zones 3-10 USDA
Native Area North America, Central America, South America
Toxicity Can be toxic when grown in the wild
Yellow squash plant

Steve Cicero / Getty Images

Crookneck Squash Plant Care

Crookneck squash are best grown from seeds planted directly in the ground. They like loose, moist, fertile soil but can grow in almost any type of soil. They need warm temperatures to bear fruits.

These fast-growing plants can spread 3 to 4 feet across with leaves that are 1 to 2 feet wide, so give them plenty of room. Read about your variety and space your seeds or transplants as directed on the plant tag or label. Thin seedlings as directed.  

Because they’re bush plants, crookneck squash don’t have to be staked and can grow in large containers or in the ground. However, you may want to put cages around garden plants to keep the leaves from flopping over in bad weather. The fruits usually mature in 45 to 55 days. Keep them picked, and the plants will bear until frost.

Light

Crookneck squash need 6 to 8 hours a day of full, bright sun to produce fruit. The plants can be grown indoors, in large containers with drainage holes and well-draining potting soil, near a bright, sunny window or under grow lights.

Soil

These plants like a soil pH of about 6 to 6.8. They also need organically rich soil that drains easily. If you’re planting in the ground, loosen the soil and remove sticks and other debris. Improve it by working in 3 to 4 inches of compost, leaf mulch, or other organic matter.

Crooknecks can be planted in raised beds or containers in good quality, packaged potting soil. You can also make your own container potting soil.

Water

Crookneck squash plants like to stay moist, but not soggy. If rainfall is lacking, water deeply with 1 to 2 inches of water per week. Avoid getting water on the foliage, which makes it vulnerable to diseases and attractive to pests. Water early in the day so any damp foliage can dry out before dark. This also helps the roots absorb the water instead of losing it to evaporation. Plants grown in containers typically need more frequent watering than those in the ground.

Temperature and Humidity

Crookneck squash grow best in air temperatures of about 65 to 75 degrees Fahrenheit. They grow slowly or stop growing in temperatures below 60 degrees F. At temperatures of 85 degrees F. and above, they produce less fruit and grow more slowly. While the plants tolerate high humidity, it can encourage fungal diseases.

Container-grown plants can be moved indoors during periods of extreme heat and humidity, although they still need six or more hours of bright light daily as well as good air circulation and sufficient water and fertilizer.

Fertilizer

For best results, test your soil to determine what kind of fertilizer or amendments you need to grow crookneck squash, or ask if your local extension service agent can test a soil sample for you. These plants are heavy feeders and need regular fertilizer. Use a balanced formula such as 10-10-10, as directed on the label.  Don’t add extra nitrogen, which encourages foliage to grow at the expense of flowers and fruits.

Are Crookneck Squash Toxic?

Wild crookneck squash contain varying amounts of chemical compounds called cucurbitacins. These bitter, naturally occurring compounds help protect them from being eaten by insects and animals. They can also occur in cultivated squash accidentally pollinated by wild squash. High levels of these compounds can cause toxic squash syndrome, or cucurbit poisoning, but this is rare.

Symptoms of Poisoning

Abdominal pain, nausea, vomiting, dizziness upon standing, and diarrhea are symptoms of toxic squash syndrome. Although it’s unusual, hair loss has also been reported. Do not eat wild squash, and if a cultivated crookneck squash tastes bitter or unusual, spit it out. Do not swallow even one bite. If you have symptoms, call your doctor. Most people recover in a few days.

Crookneck Squash Varieties

  • ‘Early Summer’ is an heirloom crookneck variety with a meaty texture and yellow-gold skin. The plants take about 53 days to mature.
  • ‘Pic-N-Pic’ is a hybrid summer squash that bears heavily. The skins are tender and smooth, and the 8- to 10-inch fruits are ready to harvest in about 50 days. The plants spread 3 to 4 ft. and grow to 30 inches tall. 
  • ‘Sunny Supersett’ squash have sweet, nutty-tasting flesh and thin, smooth skins. The plants resist mildew and have few prickly spines. They bear early, in about 40 days.

How to Grow Crookneck Squash From Seed

For a jump start on gardening season, plant squash seeds indoors in trays or peat pots filled with well-draining potting mix about two weeks before your last frost. Give them 5 to 6 hours of bright sunlight daily and water when the mix feels dry to the touch. If you plant more than one seed per pot, thin to the strongest seedling when it has two leaves. Wait until the weather is reliably warm before transplanting.

You can also sow the seeds directly in the garden when the soil temperatures are 70 degrees F. or higher, or about two weeks after the last frost. Plant them in groups of three in slightly raised hills. Cover them with 1 inch of soil, leaving 18 to 24 inches between the hills and 24 to 36 inches between the rows. Water them in. Thin to the strongest seedling in each group.

Harvesting

Crookneck squash grow at the base of the plants, under the leaves. Harvest often so the plants keep producing.

Most crookneck squash plants have little spines on their stems and leaves, so wear gloves to avoid being scratched. Use a knife or shears to cut the fruits when they are 4 to 7 inches long, or about 45 to 55 days after planting. You can also check to see if the fruits are ready by gently pressing them with your thumbnail. If you see an indentation, they’re ready to pick. (Don’t press hard enough to cut the skin.)

Common Pests and Diseases

Crookneck squash are often plagued by squash bugs, cucumber beetles, squash vine borers, snails, and slugs.  Sap-sucking aphids and whiteflies also are common pests.

Diseases include squash blossom blight, cucumber bacterial wilt, and mosaic viruses.

Check your plants often to manage problems before they become serious. Rotate crops in the Cucurbit family, which includes crookneck squash plants, every three years.