Why Are My Pumpkins Rotting on the Vine? What to Do

Pumpkins are a versatile fruit native to the Americas. They have been a valuable part of the human diet for thousands of years. These meaty fruits are great for making sweet and savory dishes. Many people also love carving and painting pumpkins as part of Halloween decorations.

Sadly, pumpkins tend to rot on the vine before they are ready for harvesting. This can reduce or deny you quality yields at the end of the planting seasons. To prevent losing the fruits of your labor, this post explains possible causes and solutions to this problem.

Why are my pumpkins rotting on the vine?

There are several causes for pumpkins rotting on the vine.

Fungal diseases

Black rot, also called Gummy stem blight, is a common culprit in cucurbit crops. This fungal disease is prevalent in pumpkins and squash. Although it affects all the above-ground parts of the plant, fruits are the most affected. Black rot is caused by the fungus Didymella bryoniae.

Symptoms of gummy stem blight include:

  • Dark, water-soaked lesions on the stems
  • Circular, tan lesions on the leaves
  • Gummy brown ooze that exudes from the lesions
  • Wilting and death of the plant
  • Curled and mottled yellow to reddish brown leaves
  • Rot of the rind, flesh, and interior seed cavity

Excess moisture

Excess moisture in the soil resulting from the rain or overwatering can cause rot in pumpkins. Soggy soils create perfect conditions for fungal diseases to thrive. Saturated soil has less air space, which reduces the availability of oxygen for the roots. This can cause roots to suffocate and die.

Unlike plants, fungi don’t need high levels of oxygen. All that spores need is water to thrive. Fungi produce various enzymes that can degrade the cell walls of plant roots. Once the cell wall is compromised, the fungus can gain access to the rest of the plant.

So, the combined effect of fungi growth and poor oxygen supply around the roots will easily kill the plant. Since fruits heavily depend on nutrients and water from the soil, they will simply wilt and rot when the supply is cut.


Pests like squash bugs, aphids, and even some small mammals feed on pumpkins. They can damage the pumpkin’s skin by chewing or boring holes to suck sap or gain access to the soft flesh. These wounds create openings for pathogens like fungi and bacteria to enter the pumpkin resulting in rot.

Heavy pest infestations can weaken the entire pumpkin plan. Since they feed on sap, the plant’s lifeline, it makes it more susceptible to diseases that cause rotting. Some pests even burrow and feed inside the vines of pumpkins. This typically disrupts the flow of water and nutrients into the fruits.

Frost and cold temperatures

In most states, pumpkins are harvested at the end of October or early November right before heavy frosts begin. According to the University of Illinois Extension program, cold temperatures and frost can cause pumpkins to soften and rot before harvest time.

When temperatures dip below freezing (32°F or 0°C), ice crystals can form within the pumpkin’s flesh. This damages the cell walls and tissues, creating mushy spots and openings for pathogens like fungi and bacteria to enter.  These invaders can then quickly spread and cause rot.

Even if the temperature doesn’t drop low enough for freezing, cold weather can still stress the pumpkin vine. The leaves may die and fruits will automatically follow suit. Pumpkins that are harvested before they are ripe will also not store well and their flavor won’t be tasty.

How to Keep Pumpkins from rotting on the vine

Various strategies can help prevent pumpkins from rotting on the vine.

1. Provide proper watering

Undoubtedly, pumpkins need consistent moisture, especially during flowering. However, avoid overwatering as this creates perfect conditions for fungal growth. Simply water deeply at the base of the plant, allowing the soil to dry slightly between waterings.

2. Good air circulation

Proper air circulation prevents moisture from building up around the pumpkins. Space your seed well when starting and prune excess leaves around developing fruits. As pumpkins grow, place a board or hay beneath it. This prevents direct contact with the moist soil.

3. Inspect regularly

Inspect your plants regularly for signs of fungal diseases. Gummy stem blight can be controlled when identified early.  If you see any suspicious lesions, remove infected plant parts to stop the spread of the disease. You may consider using a fungicide but follow label instructions carefully.

Regular inspection is also a weapon against pests. This gives an early chance to deal with pests before they cause extensive damage. Insecticidal soap, neem oil, or other organic pest control methods can help in controlling pests on your pumpkins.

4. Careful handling

Handle your pumpkins with care when pruning, weeding, or harvesting. Careless handling can cause bruises, which can become entry points for rot. When pruning, leave a few inches of the stem attached to the pumpkin.  

5. Harvest timely

Don’t wait too long to harvest your pumpkins. This can expose them to harsh weather conditions. However, don’t pick them too early before they become ripe. Harvest when the stem begins to brown and dry out. A hard rind with a uniform orange or deep yellow color is also a sign of ripe fruits.

6. Healthy practices

When selecting pumpkin seeds, go for those with high resistance to diseases. Conduct soil testing before plating to determine if there is any disease. Additionally, don’t plant pumpkins in the same place year after year. Practice crop rotation to prevent the risk of soilborne diseases.

Final thought

Pumpkins are one of the easiest to grow even for a beginner. They don’t need any constant coddling. The vegetable grows healthy and fast when provided with regular watering, full sun, and moderately fertile soil. Pumpkins rotting on the vine is one of the common challenges many gardeners face. You can prevent this problem by ensuring proper watering, adequate spacing, and regular inspections.

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