Reasons for Broccoli Leaves Turning Yellow

Americans cherished vegetable; broccoli is a branched green vegetable with purple or frequently green flower buds. It is part of the brassica family, consisting of other vegetables like cabbage, cauliflower, and kales. You can add it to your diet and enjoy it either cooked or raw, as it contains many nutrients.

When thinking of growing broccoli, you need to know that it loves not less than six hours of full sun per day and requires soil rich in Nitrogen and slightly acidic with a pH between 6 and 7. It also needs good moist soil without sogginess, so a place with great drainage is recommended.

It would be best if you prepared the ground before transplanting seedlings or sowing by adding organic matter to the top layers of the soil. In addition, remember to plant the broccoli seeds half-inch deep into the ground and have a spacing of 3 inches apart. To have larger crowns of broccoli, you need to organize the planting into rows and a space of three feet between them.

Scientists have confirmed that broccoli has compounds known as glucosinolates that, once taken, your body can turn into chemicals. The chemical contains anti-inflammatory substances that are of great benefit that can treat different conditions.

When taking your broccoli, you expect it to be green in color, but you will be surprised that it has become yellowish. Perhaps you may wonder if you can go on and eat it or throw it away due to its change of color. But first, let’s consider why the broccoli leaves turn yellow.

Reasons for Broccoli Leaves Turning Yellow

When broccoli leaves turn yellow, it doesn’t mean it is rotting, but it’s degenerating and wilting. It is a common issue and might result from many reasons; some are detailed below.

Irregular Watering of Plant

Over-watering or watering too little can result in your plant developing problems. Frequent Watering of your broccoli will make its roots die as they will lack enough oxygen and thus be unable to breathe efficiently. Likewise, feeding your broccoli with little water will lead to stunted growth, dry leafy edges, and make it turn yellow.

Nitrogen Deficiency

Broccoli is on the top list of plants requiring rich nutrient soil for optimal growth. If your soil lacks sufficient Nitrogen, your broccoli plant will not get the nourishment it should have and therefore lead to the leaves of your broccoli turning yellow.

Fungal Diseases

It is mostly disregarded but unfortunately, it is one of the causes of your broccoli turning yellow. There are fungal infections like Fusarium oxysporum that thrive when the temperature is around 75 to 85 °F, especially in the warm spring. The fusarium yellows have a parent pattern whereby half of your broccoli plant leaves turn yellow or pale and pale green.

Black Rot

There is also a bacteria called Xanthomonas campestris, which causes a disease known as black rot. Due to excess heat or moisture, black rot affects all cruciferous plants and vegetables such as broccoli. You will notice a few yellow dots on the margin of your broccoli leaves at the start, and gradually they will grow bigger, creating a large V-shape. Afterward, you will also notice yellow fluid that will make your plant wilt.


Clubroot is a dangerous disease caused by a soil-borne fungus, Plasmodiophora brassicae, affecting sensitive plants through their root hairs. The roots swell and crack, making them experience difficulty in taking in water and nutrients as required. As the disease advances, the broccoli leaves will turn yellow and, in the end, die.

Inadequate Sunlight

All plants require sunlight to undergo the process known as photosynthesis. That means no plant will grow in a lack of sunlight. So, your broccoli plant needs up to 6 to 8 hours of direct sunlight, and the absence of that will make the leaves turn yellow.

Over Fertilization

Fertilizers provide essential nutrients to plants of different kinds, from trees to vegetables. Broccoli plants are heavy feeders; every couple of weeks, you will be required to at least provide them with a dosage of fertilizer. The fertilizers improve how the soil works, but they can be dangerous to your plants if used in excess. Using more than is required in your broccoli plant will make the leaves turn yellow.

Pest Infestation

Broccoli plants can be infested and turn yellow by pests such as cutworms, flea, aphids, cabbage loppers, mites, larvae, and beetle. The upper and lower surface of the broccoli leaf is mostly the area that young larvae like feeding on and can be evident when they come out from the underside of the leaf through small holes. The plant can also be severely damaged by dark-colored beetles, which are the size of 1.5-3.0 mm. They might reduce the plant’s growth.

Over Maturity

Broccolis takes between 48 and 115 days to mature. Once its florets have fully grown in size, they will start to develop and be ready for harvesting. The moment the central main head of the broccoli stops growing and turns into deep and vibrant green in color and has tightly packed buds but is tiny, you will know that your broccoli is now fully mature. When you leave them for more than the maturity period and don’t harvest them, the tiny buds will open, and small yellow flowers will start to appear.

Preventing yellowing of broccoli

Now that you are more informed on the causes and reasons for the yellowing of broccoli leaves let’s dig deeper into some of the steps you can take to prevent the above problems from happening. The steps will help you deal with each situation effectively.

Nitrogen Deficiency in Soil

Since the broccoli plant needs to be planted in an area with nitrogen-rich soil and your soil might have low Nitrogen, you will need to add a fertilizer rich in Nitrogen. When the fertilizer is added, you will have healthy broccoli and guaranteed high produce.

Also, remember that your nitrogen-rich fertilizer should have a low phosphorous content.

If the cost of nitrogen fertilizer is too high for you, you can resort to cropping rotation with legumes because it’s a biological and economical source of Nitrogen. When you practice crop rotation with legumes for different duration, the Nitrogen will be fixed and start accumulating in the soil and can be extracted.

Over Maturation

The moment you see your broccoli’s main shoot stop expanding and its flower buds start turning green, you need to harvest them immediately because that is the ideal time. If you leave your broccoli to go beyond this point, then know that its leaves will start turning yellow, and the taste will also reduce, and so is the nutrition.

Black Rot and Fungal Diseases

Since there is no remedy for fungi Fusarium, one of the fungi diseases that causes yellowing, the only trick to use is to try and spot them early before they start causing havoc to your plantation. When you detect the fungal disease earlier, you can prevent it from spreading to other plants.

Immediately you spot the appearance of the fungal disease, try and isolate the affected plant with immediate effect. You can also try practicing crop rotation to prevent the repeat of the same and yellowing of the crops in the future.


To prevent clubroot from infecting your plants, you need to regulate the pH of the soil around the plant. The plant infection will most likely happen when the ground you are using for the plantation of the broccoli is acidic. A recommendation is to create a safe surrounding for your broccoli by keeping a neutral pH level between 6 and 7.

In addition, you can also try and remove the infected plant to reduce the impact that might be caused by clubroot on other plants. The soil can trap the disease for ten years; hence you need to clear the environment around your broccoli plant.

Pest Infestation

The best way to deal with this problem is to engage in companion planting. In this method, you will be planting broccoli alongside aromatic plants like sage, mint, herbs, and dill. These other plants will repel insects of different types and keep your broccoli safe from infestation.

You can also try and loosely cover the broccoli plants with some lightweight clothes to prevent the invasion of pests. Another natural way is to regularly check your broccolis for any pest attack on the leaves, and if present, then manually pick them out and carefully remove the affected areas.

Irregular Watering

To prevent the yellowing of your broccoli, you need to have a well-maintained routine of watering your plant correctly. To keep the soil around the plant moist, it requires enough water, and for that reason, you need to dig down up to a depth of over two inches for the water to reach the base of the plant.

If you plant your broccoli in a sandy area, you will need to water them because the sand drains water faster. You can also mix the sandy soil with compost to improve water retention.

Alternatively, mulching can reduce the time spent watering your broccoli, particularly in hot weather conditions. You can try adding some mulch layer over the soil, and the method will assist in retaining the moisture intact in the ground.

Inadequate Sunlight

When planting broccoli, you need to look for cool weather with full sun to get the best when the harvesting time reaches. Too little sunlight can kill the plant, while when there is a bright light that directly hits the entire parts of the plant, it will thrive well. Because the plant rarely does well in an area that is indirect to the sunlight, you are advised to try and have your plantation in an area where it will get at least six hours of daylight in a day while keeping them cool in the heat.

Over Fertilization

To prevent too much use uptake of the fertilizer by your broccoli plant, you need to take in some tips to prevent them from turning yellow.

– Use fertilizers slowly released into the soil to reduce the risk of over-fertilization. These fertilizers gradually release the salts into the soil rather than all at once.

– Use compost to fertilize your broccoli to eliminate the yellowing of the leaves. Using at least 1 to 2 inches of compost layer in one or two years will thrive very well.

– During dry seasons, plants are more prone to turning yellow because the fertilizer becomes more concentrated in the soil, so it’s recommended that you wait until there is an improvement in moisture condition.

– When applying granular fertilizer, you need to deeply and thoroughly water the plants to wash out the fertilizers off the plants.

Once you have grown your broccoli, follow the guidelines to ensure its heads or leaves don’t turn yellow. Conduct inspections from time to time and check the roots and lower leaves to know if there are any problems. Please ensure the soil is of the right PH, you are using enough fertilizer, the water quantity is right, and also pick off the affected areas so that it doesn’t spread to the other plants. You can go ahead and ask the help of a gardening expert to help you solve the problems and later enjoy your broccoli.

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