With pumpkins on display almost everywhere you look each autumn, it can be easy to assume that pumpkins are an easy crop that practically grow themselves. But pumpkin plants can run into various problems throughout the growing season, with yellow, unhealthy-looking leaves among them.
There are 8 main causes for pumpkin leaves turning yellow:
- Not enough water
- Nutrient deficiencies
- Lack of sunlight
- Excessive heat
- Insect attacks
- Plant diseases
- Genetic type
- End of natural life cycle
In this article, you’ll learn more about each cause of yellow pumpkin leaves and what you can do about it. In many cases, you can still save your pumpkin plants and have a good harvest.
Let’s jump in!
8 Reasons for Pumpkin Leaves Turning Yellow
1. Not Enough Water
The first (and most common) for pumpkin leaves yellowing is that your plant is not getting enough water. Vine drooping, leaves and vines wilting and feeling slightly soft to the touch are other signs that there’s not enough moisture to keep your plant healthy and strong.
The best way to gauge soil moisture is to feel it for yourself. Stick your finger down into soil about 2 inches deep. If the soil feels dry all the way down, it’s too dry for your pumpkin plants.
This might help:
Solution: Water Deeply and Frequently
Pumpkins are vigorous growers, and they do best in moist soil, well-draining soil. In general, pumpkins need about 1 inch of water per week.
However, the type of soil you’ve got can be a significant factor here. The sandier the soil, the more watering the pumpkins will require. If there’s clay, less watering is required because clay tends to hold on to moisture. Take a close look at your soil to get a rough idea of the sand/clay components you have to work with.
Soil that’s high in sand will be very loose and crumbly. To find out if your soil has a lot of clay, roll a small handful of damp soil between your hands to form a ball, then squish the ball. If the soil forms a ribbon, you’ve got a pretty heavy clay component.
Invest in a good soaker hose and run the water long enough to moisten the soil deeply. Not only will a soaker hose save you time in manual watering, but the design also keeps the leaves dry, preventing diseases and scalding in hot temperatures.
2. Nutrient Deficiency
Another cause for pumpkin plant yellow leaves could be a nutrient deficiency in the soil. Pumpkins require nitrogen for early vine growth and root development, potassium when pumpkins are growing and other trace minerals for various plant functions.
Any deficiencies in these nutrients can cause slowed growth of the pumpkin plant and pumpkins, as well as pumpkin leaves yellowing. And where the yellow discoloration shows up on the leaf can be a clue about which deficiency you’re dealing with:
- Yellowing on the entire leaf is a nitrogen deficiency (this is the most common cause of pumpkin leaves yellowing)
- Yellowing on the leaf margins indicates low potassium
- Yellow near the leaf central vein could be a lack of magnesium or iron
Solution: Apply Fertilizer
Use the right fertilizer for the right growing stage of your pumpkin vine. These come in a variety of formulations and concentrations, so always follow the manufacturer’s instructions for diluting and applying fertilizer for the best results.
Start with manure or compost in the soil before planting.
From germination up to right before the flowers form, use a fertilizer high in nitrogen to boost healthy green foliage. Blood meal, like this one from True Organic, is ideal.
Once blooming starts, the situation calls for phosphorus. So a bone meal fertilizer, like this one from Jobe’s Organics, is best.
3. Lack of Sunlight
Pumpkins are sun-lovers, and they require at least 6 hours of direct sun every day. If they get less, your pumpkin plants can’t photosynthesize optimal amounts of sugar, leading to slow growth and yellowing leaves.
A lack of sunlight is often due to something blocking the sun’s rays from reaching the pumpkin patch:
- A house shadow
- Overhanging trees
- Nearby bushes
- Taller garden plants
Solution: Increase Sunlight Exposure
Increasing sunlight exposure may not be the easiest thing to do- especially if there’s a house or tree that’s the issue.
Trim back any shady tree branches that you can, and also give overgrown bushes or shrubs a good pruning. You may also want to consider moving shrubs/bushes to a different location if they’re not too large.
But even if there’s not much you can do about the sunlight exposure this year, don’t count it as a total loss. Once you’ve learned where the most sunlight hits your yard and garden, you can plan where to plant your pumpkin plants next year.
4. Excessive Heat
The optimal range for pumpkin growth is 65 degrees 95 degrees Fahrenheit. Depending on the USDA hardiness zone you live in, it can get challenging at times to foster their growth.
If daytime high temperatures stay above 95 degrees for more than a few days in a row, pumpkin vines can suffer and start turning leaves yellow.
Solution: Shade, Mulch and Water
You don’t have control over the weather that comes your way, but you can take some steps to control the conditions in your pumpkin patch. If temperatures are getting too high for your pumpkin plants, try these strategies to help them out through the hot spell:
- Water more frequently. High temps mean more water loss through evaporation and soil will dry out faster.
- Add mulch around pumpkin plants. Mulch helps maintain soil moisture levels between waterings and keeps soil temps a little cooler.
- Consider adding temporary shade. Some dark garden fabric or a tarp tied across some garden stakes can provide some much-needed shade during the hottest part of the day.
5. Insect Attacks
Insect attacks could be another cause of pumpkin leaves yellowing. The two most common pests are:
- Squash bugs
- Squash vine borer
Squash bugs resemble stink bugs, and they tend to gather on the undersides of leaves. Their eggs are small, red, and round and found in groups on leaf undersides.
If you see a dark insect with metallic green and clear wings with an orange or red-spotted abdomen, this is a squash vine borer. Larvae of the squash vine borer are white to gray and about an inch long, and they will burrow into plant stalks.
Solution: Treat Infestations
To deal with squash bugs, take a container of soapy water out to the pumpkin patch and manually knock the bugs into the water. Be sure to look carefully over each pumpkin plant, turning leaves over to get a good look underneath.
If you spot any eggs, remove and destroy them. This video from OYR Frugal & Sustainable Organic Gardening does a great job demonstrating an easy technique for getting rid of squash bug eggs:
To prevent future squash bug problems, be sure to keep the garden clean. According to the University of Minnesota Extension, removing dead plant matter and leaves is the best way to prevent a squash bug infestation.
Also, planting your pumpkins early in the season can help protect against squash bug damage. Squash bugs usually strike in early to mid-summer, and older, established plants are better able to withstand an attack. Stop by our post on the best time to plant pumpkins to learn more about planting times for your area.
Unfortunately, if you’ve already got squash vine borer larvae feeding on your pumpkin plants, you may not be able to save them. If you think the infestation is in its early stages, do this:
- Take a sharp knife and make a shallow slit up the affected stem. You’re looking for the larva, and if you see one, gently pull it out and dispose of it.
- There are often more than one larva in a stem, so continue making a slit and removing the larvae until you see healthy plant tissue.
- Carefully cover the slit stem with fresh soil. Hopefully, the pumpkin plant will send out new roots from the buried stem section.
Adult squash vine borer moths are drawn to yellow containers filled with water, where you trap them for removal. Braconid wasps are a natural predator of the squash vine borer, and planting flowers that form multiple small blooms is a great way to attract them:
- Sweet alyssum
- Plants in the carrot family: Queen Anne’s Lace, dill and fennel (allow to flower)
- Herbs that have gone to flower
You can also cover your pumpkin vines with lightweight fabric in mid-summer (when the adult squash vine borers are active) for 2 weeks.
6. Plant Diseases
Another reason behind pumpkin plant yellow leaves is some common plant diseases, often these three:
- Downy mildew
- Verticillium wilt
- Bacterial wilt
Downy mildew looks like yellow spots on leaf top and gray, fuzzy growth on the undersides.
Verticillium wilt can cause discoloration of the roots and stems to a light brown, but this takes several weeks before the pumpkin plant will die.
Sudden wilt contributes to dark roots and will cause quick death of pumpkin plants.
Solution: Treat the Disease or Destroy Affected Plants
If you’re dealing with downy mildew, examine the plant to see how far advanced the disease is. If only a few leaves are affected, remove them and spray the rest of the plant with a copper fungicide or a mixture of 1 tablespoon baking soda to 4 cups of water.
For plants that are severely infected with downy mildew, your best bet is to pull the plant and discard it in the trash.
If verticillium wilt or sudden wilt is the problem, you will, unfortunately, not be able to save your pumpkin plant. Pull it immediately and dispose of it in the trash, not by burning or composting.
For future disease prevention, follow these tips:
- If you plant pumpkins every year, rotate where you plant your pumpkin patch. Some diseases live in the ground, just waiting until a fresh batch of pumpkin plants is available to infect.
- Avoid overwatering, and don’t get the leaves wet when you water.
- Don’t overcrowd your pumpkins (or any garden plants, for that matter). Too many plants in one area stifles natural airflow and blocks sunlight from reaching the lower leaves.
7. Genetic Type
In some rare cases, a pumpkin plant may have a few yellow leaves or stems but still grows and produces pumpkins as expected. No other problems like wilting or dying plants, leaves turning brown, and pumpkins still grow normally.
Solution: Monitor Growth
It could just be what’s called a “precocious yellow”, or genetic variation in the pumpkin plant. According to the University of New Hampshire Extension, a ‘B’ gene that affects squash and pumpkins turns fruit stems and a few leaves yellow.
Nothing to worry about though-it’s mostly only cosmetic!
8. End of Natural Life Cycle
It’s nearing the end of the growing season, your pumpkins are big and colorful, but the pumpkin leaves are turning yellow.
It also looks like the vine is starting to dry out and die. Should you be concerned? Good news: No!
Solution: Get Ready to Harvest
When the pumpkin leaves start turning yellow and the vine starts drying out and dying off, it probably means your pumpkins are ready for picking.
If you touch a pumpkin and it’s firm, the skin is bright orange (or appropriate for the type of pumpkin you planted), it’s time to harvest your pumpkins!
But if one pumpkin is ripe, don’t assume all your pumpkins are ready for picking. Check each individual pumpkin before harvesting as they can ripen at slightly different times.
Frequently Asked Questions about Pumpkin Leaves Turning Yellow
Pumpkins are a fun plant to grow with many uses, but they can be a bit finicky at times. Pumpkin leaves turning yellow doesn’t mean death is imminent, just that something is going on that probably needs addressing.
Hopefully, you’ll be able to find the answers to your pumpkin leaves turning yellow using the tips above. We learn best in a community, so let us know in the comments if you have any other questions or what you found and fixed the problem!