Why My Zucchini Leaves Are Turning Yellow - Reasons & Solutions

Written by Ivy

Dec 27 2022

Why My Zucchini Leaves Are Turning Yellow - Reasons & Solutions

In most climates, growing zucchini is simple. The normally dark green leaves, however, sporadically turn yellow and begin to die. This blatant sign of a problem with your plant should be taken seriously.

A zucchini leaf can become yellow due to nutrient and soil imbalances, excessive or insufficient water use, damaged roots, inadequate sunlight, and a variety of diseases and pests.

Why Are My Zucchini Leaves Turning Yellow?

There are a number of reasons why zucchini plants can develop yellow leaves, but these six problems seem to be the most frequent ones.

Here are six possible reasons for your zucchini leaves turning yellow and what to do about each one:

1: It Isn't Getting Enough Sunlight

A zucchini plant will begin to go dormant as the fall sun sets, and the leaves will start to turn yellow. It's best to let nature take its course in this case because it's a natural progression.

However, during the growing season, any indication of yellowing leaves may point to the zucchini plant not receiving enough sunlight.

Full sun, or at least 6 to 8 hours of direct sunlight each day (more is preferable), is what zucchini need to grow. The leaves on your zucchini plants may be turning yellow because of overshading.


There isn't much you can do about it other than dig up the plants and move them if your zucchini plants are located in a shaded area of the garden. (Take care not to harm the roots, as we will cover below.)

If your zucchini plants are in pots, relocate the pot to a more sunny spot. Some artificial lighting may be helpful for the zucchini plants in the greenhouse.

2: Overwatering Or Underwatering

One of the most frequent causes of yellowing leaves on zucchini plants is either too much or too little water. In this case, both overwatering and underwatering may be to blame.

Here are the differences between each and how to handle each.


Water is necessary for all plants to survive, including zucchini. To grow and thrive, however, zucchinis don't require a lot of water.

Zucchini roots that have been drowned will become stunted and unable to support the plant properly if you overwater them.

The leaves won't be able to produce chlorophyll correctly and will begin to turn yellow because the roots are unable to supply the plant with what it requires.

When growing zucchinis in heavy, clay soil, pay close attention to how much water you are giving them.

Clay soils are particularly prone to overwatering because the tightly packed soil particles trap water and prevent it from draining away.


Waiting until the soil dries out should be your first course of action if your ground is saturated. You can start watering again moderately after the soil has sufficiently dried out. The weekly water requirement for a zucchini plant is only 2 to 3 cm (1 inch).

Sticking your finger into the soil and feeling how moist it is will allow you to quickly determine whether your zucchini plants are receiving enough water. It is time to give them water if the top 2 cm to 5 cm (1 to 2 inches) is dry. In the event that it is still damp, recheck in a day or so.

If your soil is clay, adding compost before planting and using it as a mulch throughout the growing season will greatly assist in releasing the tightly compacted soil and allowing extra water to drain away.


Zucchini leaves can turn yellow if they don't get enough water. When the roots of the zucchini plant absorb water, they also take in nutrients from the soil to feed the plant (and create chlorophyll).

Water is necessary for plants to produce chlorophyll, so without it, the leaves will begin to yellow and die.

Here, sandy soil may work against you because water will be able to easily wash through the loose soil particles. Make sure to regularly check your soil to make sure it isn't drying out if you're growing zucchini in sandy soil.


Simply begin watering your zucchinis to fix the situation. Using the aforementioned principles, drink water in moderation.

If you pour a lot of water on your dehydrated zucchinis, the majority of it will either wash away or you'll end up overwatering them.

Always water regularly.

Once more, compost can help your sandy soil retain water. Composting will humus to sandy soil and help bind the sandy soil together. You won't lose as much water to runoff thanks to both of these helping with water retention.

3: Damaged Roots Can Cause Yellowing Leaves

Perhaps you recently relocated your zucchini plant, but now the leaves are turning yellow. Another possibility is that you worked next to the plant and now the leaves are yellowing and wilting.

If so, you may have harmed your zucchini plants' roots. Once the roots have been harmed, they won't be able to give the plant all the food and energy it needs to continue growing well and healthily. Some of the leaves begin to wither as a result.


Unfortunately, there isn't much you can do to change this. Try to avoid putting the plant under any additional stress by removing any yellow, dying leaves to prevent them from rotting and allowing disease to spread.

In order to reduce the strain on the healthy roots, make sure the zucchini receives enough water.

Why My Zucchini Leaves Are Turning Yellow

4: Nutrient and Soil Deficiencies That Cause Zucchini Leaves to Turn Yellow

Chlorophyll is produced in large part by the element iron. Although a zucchini plant only requires a small amount of iron to produce healthy, green leaves, there are a number of reasons why your plant cannot get enough iron.

First, the iron content of your soil may be low. However, a much more likely problem is that the roots are unable to access the iron in your soil because it is trapped there.

If there is too much calcium, manganese, phosphorous, copper, potassium, zinc, or any combination of these elements, the iron may become bound in the soil and unavailable to the plant.

The cause of yellowing zucchini leaves may also be insufficient nitrogen. It's important to make sure your zucchini are getting enough nitrogen because it's necessary for healthy stem and leaf growth.

Additionally, check the pH levels in your soil. The pH of the soil should be between 6.5 and 7.0 for zucchinis. Yellow leaves may result from more alkaline soil.

How To Prevent Nutrient Deficiencies

A sample of your soil should be tested as the first step in addressing nutrient imbalances. In this manner, you are fully aware of the situation and what should be added.

Although most people think that adding fertilizer will correct a nutrient imbalance, doing so may make the situation worse and result in further leaf yellowing.

A lack of iron can be brought on by or made worse by the majority of fertilizers sold for vegetables because they are too high in phosphorous and potassium.

Compost or well-rotted manure, as with most things in the garden, can help your yellowing zucchini leaves. In addition to offering essential plant nutrition, these soil amendments will aid in balancing out unbalanced nutrient levels.

Cow manure is not the best choice if you are trying to treat iron deficiencies in your zucchinis because it is too high in phosphorous, but adding well-rotted chicken or horse manure will give you valuable nitrogen.

If your soil is too alkaline, compost can also help to balance the pH.

The Right soil ph for zucchini Plants

You should measure the pH of your soil in addition to its nutrient content. For zucchini, a pH of 6.5 to 7 is ideal. If it starts to rise above this level, the soil turns alkaline, and your leaves could turn yellow.

Along with being a rich source of beneficial nutrients, compost can also help the soil pH be corrected. So don't be afraid to use it when necessary.

5: Has Been Infected With a Fungal Or Viral Disease

While there are many diseases that can affect your zucchinis, there are three main viruses and fungi that will turn the leaves yellow.

It's critical to properly dispose of the plants after treating a disease and to NEVER compost any plant matter that has been infected.

Identify And Control 3 Common Zucchini Plant Diseases

  • Cucumber Mosaic Virus

The entire cucurbit family, including your zucchini, is susceptible to this virus. This virus will result in splotchy yellow leaves and yellow spots on the stunted fruits.

  • Solution: The cucumber mosaic virus cannot be cured. Any infected plants you find need to be pulled up and thrown away. Prevention is the best form of treatment. Because aphids are the carrier of this virus, consider floating row covers before your zucchini plants flower and companion planting to draw beneficial insects. Follow a crop rotation schedule of three to four years.
  • Fusarium Wilt

The cucumber beetle spreads a fungus that turns leaves yellow. Additionally, its spores have the ability to endure the winter and infect your zucchini the following year.

  • Solution: Draw predatory insects' attention, get rid of any diseased plants or leaves you spot, and use floating row covers. The fungus can be prevented from recurring by using a strict, lengthy crop rotation.
  • Downy Mildew

When it's cool and damp, downy mildew can survive. The fuzzy-looking fungus on the underside of the leaves can be used to identify it in addition to the spotted yellow leaves. The spores can survive for years in the soil and are typically spread by the wind.

  • Solution: Providing a warm, dry environment will help your plants recover from this fungus, which typically does not cause your zucchinis any harm. It's a good idea to space your zucchini plants apart to allow air to circulate and sunlight to dry things out. Additionally, a lengthy crop rotation is crucial.

6: Insect "Pests"

Your zucchini plants are home to a variety of bugs, but some of them do more harm than good.

Here are some of the "bad" bugs that can cause your zucchini leaves to turn yellow.


Aphids not only disperse the cucumber mosaic virus but also consume plant sap and rob leaves of nutrients. If your zucchini leaves are turning yellow, aphids may be to blame because of the black, sticky waste they leave behind.

Spider Mites

By sucking up the sap, spider mites, like aphids, cause the leaves to turn yellow. Indicative spider webs are left on the leaves by spider mites.

Squash Bugs

These insects consume the sap as well and leave behind yellow spots that typically turn brown. By lowering yield or obliterating young zucchini plants entirely, they can cause significant harm.

Squash Vine Borers

As their name implies, these rather large insects consume their way inside the plant, turning the leaves yellow and killing many of the plants. It is best to remove these bugs by hand.


It is time to get rid of these bugs from the garden to safeguard your zucchinis once your leaves turn yellow and you have identified them. The best way to combat bad bugs is with beneficial bugs.

Your zucchini patch will look beautiful and draw in helpful predatory bugs if you use companion planting. Your zucchini will benefit twice from this because these predators are frequently pollinators.

Additionally effective at preventing insects from infesting your zucchini plants are floating row covers. When flowers begin to bloom, don't forget to remove the row covers so pollinators can access the plants and carry out their duties.


Your zucchini plant should produce an abundance of garden-fresh zucchini if you can figure out why its leaves have turned yellow and take steps to fix the issue.

Regardless of the problem you are having, I hope this article will assist you in locating and resolving it so you can resume taking pleasure in your garden's beauty and its abundance.


Why My Zucchini Leaves Turning Yellow With White Spots

fungal disease, powdery mildew, infects zucchini, leaving whitish dust on the leaves of the plant. White spots and powder on zucchinis are most frequently caused by powdery mildew, by far. Among garden zucchini, powdery mildew is a fungus-related disease.

Why My Zucchini Leaves Turning Yellow and Brown

Bacterial wilt is caused by a bacterium, Erwinia tracheiphila, that causes plants to wilt and eventually die. Before they wilt, you might notice leaves turning yellow, then brown, or this might take place after. Another indication that a plant isn't getting enough water is if the entire thing is wilting.

Should I Cut Yellow Leaves Off Zucchini Plant

Remove any yellow leaves that are dying to keep them from rotting and admitting disease, and try and avoid further stressing the plant. In order to reduce the strain on the healthy roots, make sure the zucchini receives enough water.