All pumpkins are a type of winter squash, but some are simply grown as decoration. Most home-grown pumpkins are cultivars or hybrids of the Curbita pepo species, but there are also other pumpkin species you may run across, including C. maxima, C. argyrosprema, and C.moschata. The species readily cross-pollinate, and many commercial varieties are carefully developed hybrid types. Like most squash, pumpkin is a low-growing vining annual with large, coarse leaves. The plants flower with yellow blooms in July and August, producing rapidly growing fruits that are left to ripen on the vine for the fall harvest. Pumpkins require quite a long period of frost-free weather (75 to 120 days) to mature, and they also need warm soil temperatures (at least 60 degrees Fahrenheit) for the seeds to germinate. For this reason, they are typically seeded into the garden as soon as the soil is sufficiently warm in the spring. In regions without the necessary long growing season, pumpkins are often started from seeds indoors two to four weeks before the last spring frost. Pumpkins can be grown in containers, although they require very large pots to accommodate the plant’s mature size. Keep in mind that pumpkin vines can grow up to 20 feet long with a spread of 15 feet; because of this, most gardeners choose to plant pumpkins directly in the ground in an open space.
Pumpkin Plant Care
Light
Like other types of squash, pumpkins require full sun (at least six hours of light per day) to produce and mature their fruits. Turn the pumpkins slightly about once per week to keep their growth symmetrical. Do this gently—it’s important not to snap the vines.
Soil
Pumpkins prefer rich, loamy, well-draining soil. Before planting, it’s recommended to mix in a good amount of organic material such as compost or peat moss. Soil pH should be slightly acidic, falling in the range of 6.0 to 6.8.
Water
Having success when growing pumpkins is largely about giving them plenty of food and water, as both are essential for harvesting large fruit. Use caution around the growing vines during waterings, as they are surprisingly delicate. Give your plants at least 1 to 2 inches of water per week, especially when they’re blooming and setting fruit. Watering should preferably be done through drip irrigation or ground-level soaking rather than from overhead.
Temperature and Humidity
Like all squash, pumpkins need heat—and lots of it—to produce good fruit. Pumpkins grow best at temperatures between 65 and 95 degrees Fahrenheit. Very humid conditions can foster fungal diseases when combined with heat, so it’s important to keep a close eye on your plants if you live in a humid area.
Fertilizer
Pumpkins feed heavily in order to develop their extensive vines and large fruit. Feed these plants every two weeks. Begin with a high-nitrogen fertilizer (10-5-5 ratio) when the plants are about 1 foot tall to support good foliage growth. Just before the plants begin blooming in summer, switch to a high-phosphorus and potassium fertilizer (5-15-15 ratio) to support fruit development.
Pollination
Pumpkins are not self-pollinating, meaning they need to be hand pollinated or pollinated by insects like bees. To manually pollinate your plants, locate the male and female flowers. Male flowers have straight, thin stems, while female flowers have a round section that appears similar to a small bulb directly below the flower on the stem. Pollination must occur while the flowers are open, which only lasts for a few hours (so it must be timed properly). Remove the stamen from male flowers, then gently apply it to the pistil of female flowers until they are covered in pollen. Once your pumpkin flowers are pollinated, the flowers will die off, allowing small pumpkins to grow from the female flower stems.
Types of Pumpkins
The best pumpkin varieties to choose will depend on how you plan to use them. Some pumpkin varieties good for cooking include:
‘Cinderella’: This variety is so named because it looks like the deep-ribbed pumpkin that transformed into Cinderella’s coach in the classic animated movie. It has thick, custard-like flesh that works well in all types of cooking.‘Lumina’: This white pumpkin works well for baking, and its rind is also suitable for carving.‘Sugar Pie’: This variety is excellent for pies since it has sweet, fine-grained flesh. It can also be used in soups and casseroles.
Pumpkins good for carving include:
‘Connecticut Field’: This variety is most often grown commercially for Halloween use. This standard orange pumpkin weighs between 10 and 20 pounds. It is not a great pie pumpkin, but it makes a great Jack-o-lantern with an easy-to-carve rind.‘Jack-O-Lantern’: Aptly named, this variety has a relatively thin rind that glows when a light source is placed inside the hollowed shell.‘Howden’: This variety is slightly elongated, weighing up to 20 pounds. Its flesh is also good for cooking.
Unusual novelty pumpkins are also available in many varieties, including:
‘Atlantic Giant’: This is a great variety for those who want to try their hand at growing mammoth pumpkins. Individual pumpkins have been known to exceed 1,000 pounds.‘Wee-Be-Little’: This miniature, baseball-sized pumpkin grows on bush-like vines.‘One-Too-Many’: This variety has creamy skin with red veins. It makes a good pie pumpkin, and it can also be used for carving or decoration.‘Red Warty Thing’: With bright orange-red skin, this pumpkin is covered with knobby “warts.” It is great for carving and can also be used in cooking.
Pumpkins vs. Squash
Aside from their obvious differences in shape, pumpkins and squash are separate plants despite coming from the same scientific genus. The main difference is in their stems; pumpkins have thick, jagged stems that are hard to the touch, while squash has a thin, hollow stem. Additionally, pumpkins have a sweeter flavor when used in cooking, and they are more often used in dessert dishes than savory meals.
Harvesting Pumpkins
Pumpkins are long-season growers. Most need somewhere between 90 and 110 days to mature. If you live in a short-season climate, make sure you choose a variety that will have time to mature in your garden. Don’t rush harvesting; your pumpkins won’t last long or taste great. A piece of cardboard or a wooden board placed under the fruit will prevent it from rotting while it matures. Wait until the color is uniform and the shell doesn’t dent when pressed with a fingernail. At this point, the vines should have begun to dry and shrivel. Watch for when the tendril closest to the pumpkin turns brown. That’s the peak time to harvest. Pumpkins can withstand a light frost, but gardeners should always harvest before a hard frost. Cut them off the vines with a pruner, leaving 2 to 4 inches of stem. This is not a handle—it’s there to help the pumpkin cure and to keep any disease from entering where the stem joins the pumpkin. Pick the pumpkin up from the bottom and try not to break the stem off. Pumpkins are quite similar to other winter squashes. They will not store through the winter, but you should be able to hold onto them for a month or two. They need to be cured to store well. Place them in a warm, sunny spot (about 80 to 85 degrees Fahrenheit) and space them far enough apart so they don’t touch. Allow them to cure for about 10 days. After curing, they can be stored in a cool, dry spot (about 50 degrees).
How to Grow Pumpkins in Pots
In most cases, growing pumpkins directly in the ground is much more favorable than growing these plants in pots. However, some growers opt for containers when they’re short on space in the garden and want to give it a try. Most importantly, remember that pumpkins require a lot of room to grow successfully—so you should have a large patio or section of your yard dedicated to housing the vines. Choose a container at least 10 to 20 gallons in size (opt for more space when growing a large variety of pumpkins). Terracotta or unglazed ceramic pots are best, as these materials do not hold excess moisture. Ensure the pot has plenty of drainage holes on the bottom. Once temperatures have consistently reached 65 degrees Fahrenheit, plant your pumpkin seeds 1 to 2 inches deep in the soil. Water the plants with about 1 inch of water per week, then begin fertilizing with a high-nitrogen fertilizer when seeds sprout. After the foliage is growing healthy, start using a high-phosphorus and potassium fertilizer.
Pruning
Pruning pumpkins is an important step to remove any fruits from the vine that are not growing healthy. Trimming back unnecessary growth is also helpful to control the size of large plants. Wait until your plant’s vine is at least 10 feet long before pruning. As the pumpkin fruit begins to form at the base of the flowers, use clean gardening shears to snip off all but a few of the developing fruits in order to direct energy to the remaining pumpkins. This is especially useful if your goal is to grow large jack-o-lantern pumpkins. Keep any vines that include pumpkins you plan to grow to maturity, and bury the cut end of the vine in soil.
Propagating Pumpkins
Pumpkins are most often grown from seed, as this method is the easiest and most effective way to grow healthy fruit for the harvest. However, it’s also possible to grow new pumpkins from your original plant by trimming its vine, which cuts down the time needed for the cuttings to reach maturity. Here’s how:
Step 1: Locate a vine from your pumpkin that has reached more than 10 to 15 feet long.Step 2: Take the end of the vine (without cutting it) and place it in a container of fresh soil, burying it about half an inch under the soil.Step 3: Water the soil in the container, keeping it moist but not soggy. Do not water the main plant. Ensure the pot receives full sun and fertilize the plant with a high-phosphorus and potassium fertilizer.Step 4: Once the end of the vine begins growing roots in the container (after about one week), it can be trimmed from the main vine using a clean pair of gardening shears.Step 5: Leave the cut end growing above the soil and trim off any large leaves. At this point, you can continue caring for both plants as usual.
How to Grow Pumpkins From Seed
Plant 4-5 pumpkin seeds in a spot with full sun about 1 inch deep in the soil, spacing groups at least 4 to 8 feet apart to give them plenty of room to grow. Keep the soil evenly moist until seeds germinate. Once the seedlings emerge, thin out the plants to keep about two or three (this applies to pumpkins planted in both hills and rows). Water the plants with 1 to 2 inches of water per week at the soil line rather than on the foliage. Apply fertilizer starting when the plants are about 1 foot tall, then prune the end of the vines once they’ve reached 10 to 15 feet in length. Continue watering weekly and fertilizing bi-weekly until it’s time to harvest.
Potting and Repotting
If you start pumpkin seeds in containers indoors, the seeds will need to be transplanted outdoors to the garden or into a larger container. Prepare the new growing location by tilling the soil (if needed), then digging a hole deep enough to contain the plant’s root system. If you’re transplanting seedlings to an outdoor container, fill it with an appropriate soil mixture. Gently remove the plants from each seed-starting pot, then plant them in their new garden plot or container. Water the soil under your pumpkin’s foliage and care for it as usual.
Overwintering
Since the growing season for pumpkins is from early spring to fall, it’s important to harvest your plants before the first hard frost of winter. These fruits must be replanted every year—your pumpkins will not come back in the spring on their own. Thankfully, it’s easy to store pumpkin seeds over the winter to grow new plants from your original harvest.
Common Pests and Plant Diseases
Pumpkins are prone to many of the pests and diseases that affect other types of squash. Most damaging are vine borer insects that can infiltrate the stems and kill the plants. Vine borers are hard to treat, so the best approach is prevention—wrapping the base of the vine where it meets the soil with tin foil or another shielding material. Squash bugs and cucumber beetles can also be a problem with pumpkins. Squash bugs most often affect young plants, causing them to wilt and die. The best preventive measure is to regularly inspect plants and pick off the red eggs or grayish insects. A variety of pesticides approved for pumpkins will kill these insects, but chemical controls should be a last resort. Cucumber beetles are small, striped beetles that eat holes in leaves and cause them to turn yellow and wilt. You can prevent cucumber beetles by using row covers over the plants, but these will need to be removed when it is time for the flowers to pollinate. Powdery mildew is the most common disease of pumpkins. It is caused by fungal spores in the soil splashing up onto the leaves. It is very hard to prevent or treat, though there are mildew-resistant varieties of pumpkins you can grow. Fortunately, powdery mildew is rarely fatal—just somewhat unsightly. Pumpkins can also fall prey to anthracnose—a more serious fungal disease. Anthracnose causes dark, sunken lesions on the leaves, and it can also affect fruits that lie on the ground. It thrives in wet, warm conditions and is spread by rainfall or during watering. Remove and destroy any damaged plant parts as you spot them, and keep the ground free of debris. Once anthracnose is widely present in the soil, you should rotate crops for the next season. Don’t plant any pumpkins or Curbita species in that area for two to three years.
