Is Your Zucchini Turning Yellow and Rotting? (Here’s why!)

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Is Your Zucchini Turning Yellow and Rotting

Due to its amazing taste and multiple benefits, zucchini has always been a member of most home gardens. Also, this tasteful vegetable is cultivated on a large scale worldwide. However, sometimes this plant may suffer from some disease that causes it is rotting and yellowness. You might wonder why is your zucchini turning yellow and rotting?

Generally, zucchini turns yellow and rotting because of poor pollination, blossom end rot, and diseases or pests. Blossom end rot is typically caused by a calcium deficiency in the fruits. Additionally, when zucchinis’ leaves turn yellow, diseases or insects are highly likely culprits.

Read on to find out more about the reasons why is your zucchini turning yellow and rotting, how to prevent or get rid of the yellowness and rotting of the zucchini some symptoms of defective plants.

You might also enjoy reading: 13 Effective Zucchini Companion Plants To Try Now!

What Are The Characteristics Of a Zucchini Plant?

Summer squash (AKA zucchini) is a member of the Cucurbitaceae family. Its fruit has a unique taste that is loved universally. In some regions, its fruits also prove beneficial as these are used in some tasty recipes.

Interestingly, zucchini, pattypan, yellow squash, and crookneck are all the same species and genus.

The table below contains all the essential characteristics of zucchini. 

Botanical name Cucurbita pepo
Common names (1) – Zucchini (most commonly known in America)
– Yellow squash
– Pattypan squash
– Scalloped squash
– Courgettes (in parts of Europe)
– Vegetable marrow (in the UK)
– Long marrow
– Garden marrow
Life Cycle– Annual
– Tender annual
Soil Drainage– Zucchini requires loose soil, well-drained, and highly fertile
– Abundant and consistent moisture is required from when plants emerge until fruits begin to fill out.
pH requirementsBetween 5.8 and 6.8.
Sun exposure Full sun
Height12 to 36 inches (30.48 to 91.44 cm)
Spread24 to 48 inches (60.96 to 121.92 cm)
Maintenance Easy to Grow
Zucchini Bloom Time– Late summer
– Mid-summer
– Early fall
Flower colorYellow
Time to MaturityIt takes about 35 to 60 days, depending on the zucchini variety.
Harvesting ZucchiniThe best way to harvest zucchini fruits is by cutting the stem to a point where you leave 2 to 3 inches (5.08 to 7.62 cm) between the fruit and the undamaged stem, according to the University of Florida.
– Frequently harvesting will keep your zucchini plant more producing fruits.
– Ensure you wear protective gardening gloves when harvesting your zucchini.
Companion Planting– Nasturtiums
– Corn
– Peppermint
– Parsley
– Spinach
– Beans
– Dill
Avoid Growing With– Potatoes
– And other cucurbits
– Squash bug 
Striped cucumber beetles
– Squash vine borer 
Diseases– Bacterial wilt (AKA Erwinia tracheiphila)
– Powdery mildew 
– Scab 
– Downy mildew
USDA Hardiness Zone3 to 9
Region of OriginNorth America
Table Displays An Overview of Zucchini Plants Characteristics –

Why Are Zucchini Turning Yellow And Dying?

Though a commonly cultivated plant of the squash family, zucchini may cause headaches due to certain problems. Some problems with this crop result in the death of the plants or yellowing.

Here are some reasons that may cause such issues. 

1- Poor Pollination 

One common issue that may cause yellowing of the zucchini plant’s leaves or fruit is poor pollination.

Poor pollination, in turn, results in weak fruit that may eventually drop before they are ripened. This premature dropping of the zucchini fruit is called fruit abortion.

Those areas that feature less exposure to those insects that cause pollination of the zucchini feature the yellowing of the fruit more. 

Tips On Hand-Pollinating Zucchini:

Hand-pollinating zucchini is an easy method that requires a gentle touch and a steady hand. There are two ways to accomplish this. 

  • You can gently pick the male flower and push it into the female flower.  
  • You can use a small paintbrush. Using a small paintbrush is the preferred way for most gardeners because it will not cause damage to your plants.
  • To ensure insect pollination, try to grow other plants near zucchinis, such as companion planting, which can attract more pollinators to your zucchinis. Some good companions for zucchinis include nasturtiums, corn, oregano, rosemary, and peas (check the table above for more ideas). 

See also: How To Grow Broccoli Indoors (A step-by-step guide).

2- Blossom End Rot

Blossom end rot is another major reason that may cause the yellowing of your zucchini plants or may cause premature fruit dropping. One of the major causes of this plant disease is a deficiency of calcium in the soil where you have planted these plants. Deficiency of some other nutrients may also result in this issue. 

Blossom end rot is caused by low soil pH or stress on zucchini plants due to unusually harsh weather (cool or hot), drought, or even wet soil conditions, according to North Carolina University.

The Blossom end rot not only results in yellowness of the plant leaves and other parts but may also cause poor growth that will result in short plants. Also, this may result in malformed foliage. This issue also affects the chilies, eggplants, cucumbers, and tomatoes

Tips For Preventing Blossom End Rot:

  • Act before it is too late; prevention is always better than remedies. If your zucchinis have already turned yellow, it may be too late. 
  • Maintaining consistent soil moisture levels is required to stop blossom end rot, according to Cornell University.
    • Water during dry weather because most vegetables need between 1 to 1.5 inches (2.54 to 3.81 cm) of water every week from irrigation or rainfall to grow well.
    • If there is a shortage of rainfall where you live, water your plants once or twice a week.
    • Water your zucchini uniformly and thoroughly.
  • Before planting your plants, add an appropriate fertilizer that includes low nitrogen. Adding too much nitrogen will lead to a growing imbalance between the roots and the leaves.
  • Adding lime to balance the soil pH is another way to prevent blossom end rot on zucchini. As you can see in the table above, zucchini thrive in pH between 5.8 and 6.8. You can buy a Soil pH Meter on Amazon to test your soil.

3- Pest Attacks

Pests are also reasons for many diseases, and blossom end rot is one of them. So, those pests that are not involved in pollination will surely affect the plants negatively. These insects will cause the transformation of different viruses that, in turn, will cause poor nourishment of the plant’s fruit and flowers.

Aphids are one of those insects that commonly affect such plants. According to Purdue University, Phytophthora capsici is a fungus that can destroy a field of squash.

See also: Everything You Must Know To Grow Green Beans Indoors Successfully.

Tips For Preventing Pests On Your Zucchini:

  • Squash bug
    • Handpick
    • Compost or bury plant remains after harvest.
  • Squash vine borer
    • Remove them by hand and destroy them.
  • Striped cucumber beetles
    • Make adequate netting or cheesecloth tents.
    • You can also use floating row covers over young plants.
    • Place at planting and remove at flowering.

4- Cucumber Mosaic Virus 

A virus that may cause the premature fruit dropping or dying of your zucchini plants is the ‘Cucumber Mosaic Virus. This virus is caused by a certain type of aphid that usually feeds on the foliage of the zucchini. 

5- Zucchini Diseases

  • Bacterial wilt (AKA Erwinia tracheiphila)
    • Remove and destroy infected plants.
  • Powdery mildew and Scab
    • Avoid wetting leaves if possible.
    • Water early in the day to allow the aboveground parts to dry as quickly as possible.
    • To improve air circulation, avoid crowding zucchini plants and eradicate weeds around plants and garden areas.
  • Viral disease
    • Remove and destroy the whole infested plant surrounding soil and soil clinging to roots immediately.
    • Eradicate wild cucumber and milkweed nearby.
    • Plant-type Multipik to hide symptoms on fruit.
    • More importantly, control aphids early in the season by washing them off with water early in the day.

How Do You Successfully Revive a Dying Zucchini Plant?

Hardly will there be any plant disease with no cure or prevention at all; the yellowing of zucchini is not an exception. Here are some natural and artificial ways to revive your dying and yellowing zucchini plants. 

1- Companion Planting for Effective Pollination

If you notice that the zucchini plants in your garden are turning yellow or are dying and diagnose the pollination as its cause, you can avoid this easily. One good way to prevent these plants from being yellow and from premature fruit dropping is “companion planting.” 

This method includes planting some other plants near these fruitful plants. These plants will prove true flowering friends of zucchini. When these are near your garden zucchini, they will attract pollinators. These pollinators will effectively carry out the pollination. This is an effective measurement that will prove effective in reviving your dying zucchini. 

2- Hand Pollination

If you are an experienced gardener, you will surely know the hand pollination method. This is an easy way to prevent your zucchini plants from turning yellow if this is due to poor pollination.

Carefully manage the hand pollination of these plants after you’re sure that your hands are clean and tidy. 

3- Provide Your Zucchini With an Adequate Amount of Calcium

If you find out that the zucchini are dying due to blossom end rot, which is mostly caused by calcium deficiency, you can avoid this by adding a sufficient amount of calcium to the soil.

Search for the recommended calcium quantity and maintain that recommended amount through addition or elimination. This will also prove effective in securing your garden zucchini from most damage. 

See also: Best For Turning Granular Fertilizer Into Liquid (A quick guide).

4- Provide Your Zucchini With Proper Type Of Pesticides

If you find out that the yellowing of your zucchini is due to some defective pests, you can avoid this by spraying proper pesticides on your plants in your garden.

This will also help in getting rid of aphids that may cause the cucumber mosaic virus.  

See also: What Are The Main Differences Between Fertilizer And Plant Food?

How Often Should Zucchini Be Watered?

Zucchini requires plentiful and consistent moisture from when they emerge until fruits start to fill out, according to Cornell University.

If the outside weather is cool, water your zucchini plants once a week. However, in dry and hot weather, the watering should increase to two or even three times per week.

How Do You Treat Blossom End Rot in Zucchini?

According to the North Dakota State University, here are the best ways to prevent blossom end rot:

  • Focus on watering: The uptake of calcium depends on water uptake.
  • Irrigate regularly. Avoid the extremes of waterlogged soil and droughty soil. Regularly mulch to help maintain consistent levels of moisture in the soil.
  • Grow your plants shallowly. Avoid damaging the roots of your vines because they need these roots to absorb calcium.
  • Avoid over-fertilization, particularly with ammoniacal nitrogen fertilizers, such as 10–10–10). Generally, ammonium competes with calcium for uptake. It is better to choose calcium nitrate.
  • Avoid adding Epsom salt to your soil because it may create more rot as magnesium and calcium ions compete for uptake into your plants. In addition, a deficiency of calcium causes blossom end rot, and Epsom salt generally contains magnesium sulfate and not calcium at all. 

See also: Best Of Starting Cucumbers Indoors (An ultimate guide).

Final Thoughts

Zucchini is one of the common fruitful plants that is planted in home gardens to use its fruit as a vegetable. However, it’s vulnerable to getting different diseases that may result in its yellowing, premature fruit dropping, wrinkling of leaves, or even death of the plants.

After diagnosing the reasons, you can treat these infected plants with any of the above-mentioned methods.


Hello friends, I am Altiné. I am SO excited you are here! I am the guy behind Plants Heaven is a blog that shares information about preparing, creating, and maintaining gardens in and out of your home, regardless of where you live. My goal is to help you learn to love gardening and reap the benefits that come with it. I am still learning; therefore, the information I share on this site may not always be “expert” advice or information. But, I do my VERY best to make sure the information shared on this blog is both accurate and helpful.

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Due to its amazing taste and multiple benefits, zucchini has always been a member of most of the home gardens. Also, this tasteful vegetable is cultivated at a large scale worldwide. However, sometimes this plant may suffer from some disease that causes it is rotting and yellowness. You might wonder why is your zucchini turning yellow and rotting?