Pumpkin Leaves Yellowing? 8 Causes Gardeners Should Know

Fall isn’t complete without a trip to the pumpkin patch to pick pumpkins for baking, carving, and painting. But if you chose to grow your own this year, you’ll want to be on the lookout for potential issues that can affect your harvest. One thing many gardeners encounter when growing pumpkins at home is yellowing foliage. While this is typically an indicator your plants need extra care, the underlying issue can vary. To help you diagnose the cause of yellowing leaves, we asked experts the most common reasons pumpkin leaves change color—and how to fix it.

Inadequate Watering

Pumpkins need consistent moisture to thrive. “Too little water causes plant stress, limiting chlorophyll production and leading to yellowing leaves,” says Ankit Singh, ornamental horticulture educator at the University of Maine Extension. To fix this issue, aim to give pumpkins 1 to 2 inches of water per week, watering deeply and evenly early in the day. “Use mulch to retain moisture and regulate soil temperature,” Singh says.

Age

Sometimes pumpkin leaves turn yellow simply because it’s time for them to do so. “As the pumpkin vine matures, the older leaves yellow because the nutrients are redirected to new growth,” says Linda Langelo, horticulture specialist at Colorado State University Extension. “Every plant has a certain maturity, and there is no fix to stop the older leaves from yellowing.”

Poor Soil Drainage

Although pumpkins prefer moist soil, waterlogged conditions can put stress on the roots of the plant. “This leads to nutrient deficiency in the leaves, as the roots can’t provide the leaves with proper nutrients and chlorophyll production is disrupted,” says Langelo. Our experts say you can rectify this issue by amending the soil with compost to improve drainage and waiting longer periods between watering.

Inadequate Sunlight

Pumpkins are full-sun plants that need six to eight hours of full sun daily. “Insufficient sunlight reduces photosynthesis and chlorophyll production in leaves,” says Langelo. She adds that when sunlight is scarce, chlorophyll begins to break down, leading to pale or yellow leaves. This issue can be difficult to fix once your plants are already in the ground, but trimming nearby plants that cast shade on your pumpkins can help.

Disease

It’s possible the foliage on your pumpkin plants is yellowing because the leaves are infected with a disease, such as fusarium wilt, bacterial wilt, or mosaic virus. If this is the case, Singh recommends removing infected leaves and disposing of them away from your garden. To prevent these diseases, improve airflow by thinning the vines, avoid overhead watering, and rotate your crops annually to avoid pathogen build-up.

Pests

Sap-sucking pests like squash bugs, aphids, and spider mites can remove the sap from pumpkin leaves, causing yellow spots to develop. Langelo recommends spraying the vines with neem oil to mitigate these pests. She also says to rotate your crops annually to prevent squash bugs from damaging your plants next year, as they overwinter in garden debris.

Nutrient Deficiencies

One of the most common causes of yellowing pumpkin leaves is lack of nutrients. “Low levels of essential nutrients, especially nitrogen, iron, or magnesium, can cause chlorosis (leaf yellowing),” says Singh. “Nitrogen deficiency often yellows older leaves first; iron deficiency yellows young leaves with green veins. To address this concern, apply a balanced fertilizer to the soil or amend with compost.

Environmental Stress

Various environmental stresses, such as wind damage and temperature extremes, can cause pumpkin leaves to turn yellow. To limit such stressors, our experts recommend using row covers to protect the plants from heat waves and windbreaks to shield against wind damage.