Broccoli Florets Turning Brown | 3 Causes and How to Fix Them

Growing your own broccoli is a delight because there is nothing quite the same as fresh veggies that you grow yourself. If you’re in the middle of growing these delicious heads and you notice the broccoli is starting to turn brown, what should you do?

The top 3 reasons why broccoli turns brown include brown bead due to a lack of nitrogen or water, rot due to bacteria or viruses or boron deficiency.

The fact is that there are numerous reasons why broccoli will start to turn brown, but there’s no need to panic because there are also ways that you can prevent broccoli from turning brown in the first place. In this article, we’ll go over why broccoli turns brown and what you can do about it so that your broccoli stays fresh and green all the time.

1. Brown Bead Due to Lack of Nitrogen or Water

Brown bead is not that uncommon in certain vegetables and usually affects the entire head of broccoli. It can be caused by numerous things, including certain diseases, extreme temperatures, or even poor growth. If you see flowers that are turning brown and don’t seem to be growing any bigger, it is possible they could have brown bead.

The buds on your head of broccoli will usually turn yellow first and then brown. Not only does it make the broccoli look unappealing, but it can cause rot growth if the weather turns damp and wet.

Usually, brown bead is the result of lack of nitrogen or even water, but it can also be caused by too much sunlight and heat.

To greatly reduce the chances of your broccoli getting brown bead, here are a few tips to follow:

Choose fast growing varieties

Choose broccoli varieties that mature faster and therefore avoid the worst part of the summer heat and sun. These include Spigariello Liscia, Atlantis, Monflor, and Spring Raab. The Spigariello Liscia broccoli, for instance, grows to full size in just 45 days.

Water regularly and evenly

Water regularly and evenly, feeling the top inch or two of soil first to see if it’s dry. If it is, go ahead and water the plant and let the water soak down to a depth of two or more inches.

Remember that sandy soils will need to be watered more often because they drain faster. And when you water broccoli plants, water from below and during the morning hours.

Feed them with nitrogen

Make sure your soil has enough nitrogen. Keep in mind that broccoli is a heavy feeder and needs lots of nutrients, including nitrogen. Aim for 10-10-10 fertilizer in the pre-season, calcium nitrate (15.5-0-0) during post-transplant, and supplement the fertilizer on a regular basis in the meantime.

2. Rot Due to Bacteria and Viruses

Viruses and bacteria can cause broccoli to rot, and this usually affects the leaves on the plant. There are numerous types of rot that your broccoli may suffer with, including the following types:

Black rot

Black rot is caused by a bacteria known as the Xanthomonas campestris and occurs in warm, humid conditions. Black rot is usually spread by infected seeds or even insect movement, and you can prevent it by using crop rotation and by planting members of the brassica family in different spots in the garden every year.

Alternaria leaf spot

Alternaria leaf spot is caused by a fungus, this one causes small spots on the leaves that are usually either gray or brown. They may also have concentric rings. This type of rot can be prevented by planting members of the brassica family in different spots in your garden every year.

Ring spot

Ring spot is caused by a virus and is more common in cool, moist conditions, especially during the fall months. It usually starts out as purple spots on the leaves, which later become brown with olive green borders. To stop this from happening, simply use crop rotation and don’t plant members of the brassica family in the same spot each year.

Downy mildew

Downy mildew is caused by a fungus, this type of rot loves moist conditions and starts out with gray mold on the bottom of the leaves. To prevent the disease, water the broccoli from below so the leaves don’t get wet, and follow the same rules as above for crop rotation and the location of the brassica family broccoli.

3: Boron Deficiency

Boron deficiency can cause broccoli to turn brown, and almost always it happens in the stalk (stem) of the plant. Boron is an important nutrient for broccoli and helps with plant growth, although it is needed in much smaller amounts than the “big three” nutrients (NPK, or nitrogen, phosphorus, and potassium).

You’ve likely already noticed that planting broccoli in the same place many years in a row can cause deficiencies in the broccoli, as mentioned above, and this includes deficiencies in nutrients such as boron.

If you’re wondering what a lack of boron looks like, it usually appears as stems that are hollow, cracked, discolored, and corky. If the pH of your soil is too low (too acidic) or too high (too alkaline), it can result in a boron deficiency.

The good news is that you can easily test the soil to learn how much boron is in there and therefore how much you need to add to it. Keep in mind that soil that is sandy or too dry will lose boron faster due to leaching.

For more tips on how to grow broccoli at home, check out this video.


Broccoli that turns brown is always suffering from some sort of deficiency, and you can learn more about the deficiency by first noticing if the brown parts are in the head, stalks, or leaves of the plant. Once you know what you’re looking for, it’s a lot easier to determine what to do about it.

Just remember that it isn’t normal for broccoli to turn brown at any stage, so the sooner you notice the problem and do something about it, the sooner you can return to having fresh, delicious, green broccoli to enjoy.

None of the remedies are difficult or time-consuming, so you should be able to get rid of the problem quickly and easily.