If you grow pumpkins in your garden, then you know that there is nothing more frustrating than seeing pumpkins dying on the vine. Sometimes the pumpkins will rot, sometimes they will turn yellow, and sometimes they will simply fall off the vine.
So, why are your pumpkins dying on the vine? Over watering, diseases, and pests can all cause your pumpkins to die on the vine. Competition with nearby plants, including other pumpkins, can cause your pumpkin plant to drop some of its fruit. Soil conditions, including pH and nutrient levels, can also cause pumpkins to die on the vine.
Sometimes it is difficult to tell which problem is causing your pumpkins to die off. We’ll go through some of the common ones in more detail here, along with ways you can solve the problem and prevent it in the future.
There are several mistakes you can make when watering your plants, but the most common is over watering. In effect, you are “killing your plant with kindness” by adding more water than it needs. For more information, check out my article on over watering your plants.
When you add too much water, the soil stays wet for too long. Over time, this causes root rot, especially if your garden has clay soil, which drains poorly.
When the roots of your pumpkin plant rot and die, the plant is unable to absorb water from the soil. So, as strange as it may seem, overwatering can eventually lead to the same symptoms as a lack of water, including yellow leaves and wilting vines.
Luckily, there are some measures you can take to prevent the problem of over watering. First, if your garden has clay soil that drains poorly, be sure to mix some organic material (compost) into the soil before planting. To learn how to create your own, check out my article on making compost.
After you mix compost into your garden, create mounds (3 feet in diameter) and plant the pumpkins on top of the mounds. This will allow for better drainage of the soil, so that it doesn’t stay wet and cause root rot.
Finally, keep the soil moist, but not soaking wet. The best way to do this is to feel the top 2 or 3 inches of soil with your hands. If it feels dry, add more water.
Also keep an eye on the weather forecast. If a big storm is coming, avoid giving the pumpkin plants a heavy watering – let nature do it for you.
Usually, you will want to water in the morning when it is still cool, so that the sun doesn’t evaporate the water. Make sure to water near the ground and avoid splashing the leaves, since wet leaves promote disease in a plant.
If you find that your pumpkins are growing fine, but end up rotten on the bottom, then try this fix. Put a small piece of wood (a plywood board would work) under each pumpkin that appears on the plant.
This will prevent the pumpkin from touching the moist soil, leaves, or grass, and hopefully prevent rotting of the fruit.
It is also possible to under water your plant, but you will see signs of this long before the pumpkins fall off the vine. Signs of under watering include yellow leaves, shriveled or wilting vines, and soil that feels dry to the touch.
Pumpkin plants are subject to a number of diseases, even if you water them properly and give them the right nutrition. Let’s take a look at some of the more common ones.
Your young pumpkins will turn black and rot on the vine. An early sign to look for is the appearance of bronze patches on the pumpkins, or reddish-brown spots with bumps or black dots in the center of the spots.
Your fruit will have wet-looking spots that are circular and sunken. You may also see pink spores.
Brown spots with yellow on the outside appear on leaves. These spots become “crispy” and then fall away. The fruit may develop white spots or rot on the vine.
Large yellow patches appear on leaves, which then get larger and turn brown. A purple mold develops on the bottom of leaves.
White or gray patches appear on top of leaves, which slowly turn brown and die off.
The leaves on one side of the plant wilt, curl up, and die. If you cut open a stem and see dark streaks, then your plant has fusarium wilt.
The roots will feel mushy, and will be black or gray. Unfortunately, the only way to tell is to dig to find the roots, which may disturb the plant.
The leaves will turn yellow, starting with the oldest (the leaves closest to the vine) and moving to the youngest.
Blossom End Rot
A brownish-black spot appears on the bottom of the fruit, due to calcium deficiency. This can occur if the calcium is depleted in the soil. For more information on how to treat this problem, check out my article on treating calcium deficiency in plants.
More likely is uneven watering or excessive magnesium, both of which can block calcium uptake by the plant. If you add too much Epsom salt to your soil, you can end up with excessive magnesium.
How to Combat Plant Diseases
One of the best ways to prevent the appearance and spread of plant diseases is to practice crop rotation. This means that you do not plant the same crop in the same part of your garden every year.
Ideally, you rotate between four groups of crops in four different parts of your garden. Not only does this prevent disease, but it also prevents nutrient deficiencies in the soil.
If you do end up with a plant disease, your best bet is to sanitize. First, dig up the infected plants, and dispose of them. Do not put them in your compost pile, since some diseases can survive for years in a compost pile.
Then, cover the soil with clear plastic, and weigh down the sides of the plastic with rocks. Leave the sun to do its work for several weeks, by heating up the soil and killing any pathogens that may be present.
Leave the affected soil unplanted for a season, and be sure to sterilize any tools you use in your garden. To sterilize your tools, wash them with soapy water or bleach solution (10% bleach).
For more information, check out my article on how to sterilize your garden soil.
To prevent disease in the future, choose crop varieties that are disease-resistant.
Pumpkin plants are not immune to pests either. Here are some common ones that you might see in your garden. If these pests do enough damage to the plant, it may drop some of the fruit in an attempt to conserve energy and survive.
These are tiny insects that are green, gray, or black. They gather on the bottom of leaves, sucking the juice out of leaves and vines. Sometimes, ants will tend them like livestock in order to access the sweet “honeydew” that aphids excrete. For more information, check out my article on how to get rid of aphids.
These yellow or orange beetles will “skeletonize” leaves, meaning they eat the soft parts between the veins of the leaves.
These bugs are brown and somewhat oval-shaped, and they suck juices out of stems and leaves, much like aphids. Damaged leaves have pale green or yellow specks, which indicate areas where squash bugs have been feeding.
Squash Vine Borers
A sign of these insects is a hole in the stem, with yellow “sawdust” around the opening. Squash vine borers can disrupt the flow of water to the leaves, flowers, and fruit of the plant. The vines can wilt suddenly if squash vine borers are present.
If you see silver or gray trails through your leaves, which start small and get larger, then you have leafminers. These little maggots (baby flies) create tunnels inside the leaves.
These insects are bright white, and when they are present, you will see a clear, sticky residue on the leaves. You may see a black coating that can be rubbed off (sooty mold), which grows due to the sticky residue.
Combating Garden Pests
There are some ways to prevent pests from ruining your pumpkin plants. Pesticides are one option, but I would only use them as a last resort.
Many of these pests have natural enemies that can keep them in check. For example, ladybugs are natural predators of aphids, so releasing some ladybugs into your garden can help to control the aphid population.
You can also try companion planting, which means planting pumpkins together with other plants that drive off pests. For example, marigolds are thought to deter beetles.
The way you are planting your garden can also have an impact on the health of your plants. If you plant your pumpkins too close together, or too close to other plants, then they could end up competing with one another for water and nutrients.
If the plants are overcrowded and competition gets fierce, some of the plants may drop some of their fruit, in order to conserve resources and focus on survival and growing fewer pumpkins to maturity.
Each pumpkin plant should have about 50 square feet of space if it is a vine, or 12 square feet if it is a bush. For a vine, this means planting pumpkins about 5 feet apart.
Other Causes of Dying Pumpkins
There are a few other factors that can cause pumpkins to die on the vine or drop off the plant. Let’s take a look at each of them in turn.
The ideal pH range for a pumpkin plant is around 6.5. If the soil pH is too high or too low, it may prevent the plant from absorbing certain nutrients from the soil. For more information, check out this article from Research Gate on nutrient availability by soil pH.
To find out you soil pH, you can buy a test kit online or at a local garden center. You can also send your soil to be tested at your local agricultural extension. To learn more, check out my article on soil testing.
If the pH is too high (alkaline), you can add sulfur to lower the pH. If the pH is too low (acidic), you can add lime (calcium carbonate) to raise the pH.
If you know that your soil pH is correct, then you may have an imbalance of nutrients in your soil. For instance, excessive magnesium can prevent a plant from absorbing calcium, even when there is plenty in the soil.
A nutrient deficiency can occur if you plant the same crop in the same place in your garden every year, but fail to replace nutrients with fertilizers or compost.
The best way to tell if you have a nutrient imbalance or deficiency is to do a soil test and check the results. You can find fertilizers or soil amendments that will address specific nutrient deficiencies online or at garden centers.
Sunlight and Temperature
Pumpkins like full sun, meaning that they need 6 to 12 hours of sunlight per day. Also, wait until all danger of frost has passed before you plant your pumpkins, since frost will kill them.
Ideally, the soil temperature will be 60 to 65 degrees Fahrenheit, and nighttime air temperatures will be over 55 degrees Fahrenheit.
Hopefully, you have a better idea of what is causing your pumpkins to die on the vine, how to solve the problem, and how to prevent it in the future.
I hope this article was helpful – if so, please share it with someone else who can use the information. If you have any questions to ask or advice about growing pumpkins to share, please leave a comment below.