Why do my broccoli leaves turn yellow? [Reasons & How to Fix]

Broccoli, America’s favorite vegetable, is extremely easy to grow and requires minimal effort, which also makes it the perfect choice to grow by yourself. But one of the main problems people face while growing broccoli is, the yellowing of the broccoli leaves. We will find out various reasons why do my broccoli leaves turn yellow?

There are 8 reasons why are my broccoli leaves turning yellow? And here are these:

  1. Not watering your plant properly
  2. Lack of nitrogen
  3. Other nutrients deficiency
  4. Over maturation of your broccoli plant
  5. Problems with roots
  6. Insufficient sunlight
  7. Using too much fertilizer
  8. Fungal infection, pests, and diseases

Why are my broccoli leaves turning yellow

If you are wondering why your broccoli leaves are turning yellow, here are a few reasons you can look into.

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1. Not watering your plant properly

Remember, both over-watering or watering too little, can cause problems. If your broccoli plant is over-watered, then the roots cannot breathe properly as it limits the supply of oxygen.

Similarly, if the broccoli pant is watered too little, this would result in slow growth and brown and dry leaf edges. If you want to check whether or not your plant is receiving a sufficient amount of water, you can check the soil a few inches below the surface.

A good time to check would be either in the early evening or morning. If you feel that the soil is dry or warm, this means your plant needs more watering.

 An ideal amount would be about 1 to 1.5 inches of water, weekly.

2. Lack of nitrogen

Broccoli, just like other green leafy vegetables, requires a high level of oxygen for its optimal growth. So in case, your broccoli plant isn’t getting sufficient nitrogen, this could lead to the yellowing of the leaves of your broccoli plant.

Thus, if your soil isn’t rich in nitrogen, you can use fertilizer, that is high in nitrogen to grow your broccoli.

However, if you don’t want to use any chemical fertilizers for your broccoli plant, there are some alternatives you can choose from – for eg, you can grow leguminous plants in your garden.

Rhizobium bacteria present in the root nodules of these leguminous plants convert the nitrogen present in air into water-soluble nitrogen compounds called nitrates.

Another option could be to add compost to the garden beds where you are growing your broccoli.

Similarly, other nutrient deficiencies include calcium deficiency iron deficiency magnesium deficiency, zinc deficiency.

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3. Other nutrients deficiency

Just like nitrogen deficiency can cause the leaves of your broccoli plant to completely turn yellow, similarly, other nutrient deficiencies could also be a reason for the yellowing of your broccoli leaves. Potassium deficiency, for eg, can make the leaf’s edges of your broccoli plant go yellow.

Nutrient deficiencySolution
1. Calcium deficiencyAdd lime if your soil is acidic or add gypsum if the soil is alkaline.
2. Iron deficiencyTest the pH level of the soil and if it is 7 or above, try to lower it down.
3. Magnesium deficiencyAdd fertilizer that is rich in Magnesium sulfate
4. Potassium deficiencyUse of fertilizers that is rich in potassium.
5. Zinc deficiencyUse of fertilizers containing zinc

4. Over maturation of your broccoli plant

Broccoli is ideally planted in early spring and harvested in summer. It usually takes 48 days 115 days to mature. The broccoli florets will start to mature, once they have grown to their full size, and thus they need to be harvested on time.

The leaves of the broccoli plant, however, don’t get affected much by maturation, until and unless the season ends for it.

You will get to know that your broccoli has fully matured when the main, central broccoli head stops growing further and is deep and vibrant green in color with tiny, tightly packed buds.

Thus, you need to harvest them before these buds open and start to show small yellow flowers.

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5. Problems with roots

Compacted roots or damaged roots of the broccoli plant often reduce the movement of nutrients, water, and oxygen, which in turn might result in the yellowing of the broccoli leaves.

If possible, you can check the root health of your plant. Healthy broccoli plants have whitish-yellow roots. Damaged and rotten roots will have a foul smell and will be darker in color.

Root rot can be yet another reason for your broccoli leaves turning yellow. This condition is more common in indoor plants. As we can already make out from the name, it is a condition where the root of the plant rots.

It is usually caused in cases where there is poor drainage, waterlogged soil, or it can also be caused due to some fungi, such as Armillaria mellea, Clitocybe tabescens.

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6. Insufficient sunlight

We all know that plants require sunlight to be able to do photosynthesis. So, in case your broccoli plants are not getting enough sunlight, the leaves of your broccoli plant will start to turn yellow.

The solution for this would be to simply ensure that you are growing your broccolis in an area where sufficient sunlight is available to them.

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7. Using too much fertilizer

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Fertilizer can help you in growing healthier and better plants, however, if you use an excess of it, it will do the exact opposite.

Fertilizers, if used more than required can result in stunted growth of your broccoli plants, and can cause yellowing of the leaves and other problems.

You can tell that you have used too much fertilizer if you see a layer of fertilizer sitting on the surface of the soil.

All you have to do is, remove that visible layer present on the topsoil and water them sufficiently. Wait for a minimum of 1 month, before using fertilizer again.

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8. Fungal infection, pests, and diseases

  • Fungal leaf spots – Small and brown spots with yellow margins on broccoli leaves can be symptoms caused by fungi, causing leaf spots. In such cases, you can remove the infected plant material. Try to avoid splashing water on the leaves, as this could spread the fungi. After this, you can also spray myclobutanil, tebuconazole, or Bacillus amyloliquefaciens, to reduce the chances of future disease.
  • Anthracnose – Anthracnose is caused by the fungi – Colletrotrichum and Gloeosporium. If your broccoli plant is infected by this fungi, the tip of the leaves will turn yellow, then tan, and finally, dark brown. This will eventually extend to the entire leaf and the leaf will die. To prevent further disease, picking off the infected leaves can help. You can also spray chlorothalonil or tebuconazole after this to reduce the chances of future infection.
  • Pests – Pests such as thrips, whiteflies, mites, aphids, mealybugs, etc can pest infestation, which could lead to yellowing of the leaves of your broccoli plant. Neem-based insecticidal sprays can prove to be useful in such cases. You can also boil some neem leaves in water and use this to spray over the broccoli plant. Make sure that the water cools down before you spray them.

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The leaves of broccoli plants can turn yellow for a variety of reasons. One possibility is that the plant is not getting enough nitrogen. Another reason might be that the plant is too hot or dry. A lack of water can also cause leaves to turn yellow.

Finally, some pests or diseases can cause broccoli leaves to change color. If you are concerned about why your broccoli leaves are turning yellow, consult with a local gardening expert or agricultural extension agent for help diagnosing the problem and finding a solution.