Why is My Broccoli Growing Tall | Troubleshooting Broccoli

Broccoli is a common dish served at dinner time among American households. Despite this, it can be difficult to grow in the garden. Many gardeners end up frustrated as their broccoli plants grow tall and healthy, but fail to produce the lush, dark green heads that are cooked up and served for consumption.

So why is my broccoli growing so tall? Broccoli plants grow tall as a result of stress. These plants require specific temperatures and nutrients to form a head of broccoli and without them; the broccoli plants will bolt upwards in an attempt to reproduce before it dies off.

Why is my Broccoli Growing Tall

So what kinds of stress are these plants receiving? As we talked about earlier, broccoli is somewhat of a tricky crop to grow. It requires specific growing conditions to produce a large, healthy head of broccoli. Many factors go into creating the right environment for your broccoli plants to thrive.


Broccoli is a crop that grows better in cold weather. But contrary to popular belief, the growth of broccoli is not affected by hot weather. Rather, it is affected by the temperature of the soil. Broccoli grows exceptionally well in soils that have temperatures that range between 65 F and 75 F.


Whenever the soil becomes warmer, the broccoli bolts up and begins to flower. If “why is my broccoli growing tall” is a question you have asked before, you now have an answer: bolting.

Bolting is when the cool weather plants such as broccoli begin to grow rapidly. Hence, the transition from the leaf phase to the flowering phase and then to the seed phase occurring very fast. In essence, bolting is a survival mechanism for the plant.


That’s why once the temperatures surpass the survival conditions for the broccoli, it tries to produce the seeds for the next generation of growth quickly. As a result, the broccoli grows tall, woody, and tough.


At this point, the broccoli is no longer edible since most of its energy is reserved for producing seeds. A bolted broccoli is usually tasteless and bitter.

How to grow Broccoli in Hot Weather

young broccoli plant

It is possible to prevent bolting. All you have to do is keep the soil cool throughout the broccoli growth process. Some of the ways that you can ensure the soil remains cool include:

Practice Mulching

 If you want to grow your broccoli during the hot weather, you should greatly consider mulching. The hot weather only affects the plant if it gets to the roots. Therefore, placing a thick layer of mulch will ensure that the broccoli roots remain cool. The result? Your broccoli will not bolt.

Using Row Covers

Place row covers over your broccoli. They will prevent the heat from the sunlight from reaching your broccoli. Your soil will also remain cool. Thus, your broccoli will not flower early. In addition, row covers will even help keep away unwanted pests and diseases!

Frequent Watering

Another way of ensuring the soil remains cool is to water the plant frequently. Broccoli are thirsty plants so keeping them hydrated helps ensure they grow big and stay cool throughout the growing season.

Early Harvests

You can also harvest your broccoli early to prevent the growth of flowers. Since broccoli is a plant that grows again once it is cut, you should also consider frequent harvests. Cutting the main head lets other heads grow while reducing the pace at which the side heads bolt.

Late Harvesting

As mentioned earlier, one of the ways that you can use to ensure that your broccoli does not bolt is through practicing early harvests. Even though your broccoli has well-formed heads, leaving them unharvested longer than is necessary will encourage bolting.

So, what will make you avoid the question “why is my broccoli growing tall?

First, we will look at the signs that indicate that the broccoli is ready for harvest. They include:

Ripe broccoli growing in garden

Present head

This might seem obvious but it is a worthy mention. The initial head has to be present before you decide to harvest your broccoli. Also, the head should be tight and firm.

The head size

The second thing to consider is the size of the broccoli head. Ideally, the size of the head should be between 4 and 7 inches wide when it is time for harvest. Nevertheless, do not rely on the head size alone when determining the time of harvest.

The floret size

The size of the broccoli florets might be the most significant indicator that it is time to harvest. Look at the florets on the outside edge of the head. Are they the size of the head of a match? If yes, then you can harvest your broccoli.

The Color

Another obvious factor to consider is the color of the florets. Deep green florets are ready to harvest. Florets that have a yellow hint are either starting to bolt or bloom. If this happens, harvest the broccoli immediately.

What is the best way to harvest broccoli?

You must use a sharp knife when harvesting your broccoli. Ensure that you swiftly cut the head of the vegetable off the plant with the stem measuring at least 5 inches below the head.

Remember not to saw at the stem since this might ruin the chances of future harvests as a result of damaging the plant. Once the main head is removed, you can start harvesting the side shoots. Remember, letting the broccoli grow larger will only reduce the flavor and increase bitterness.

Inconsistent Watering

Another cause of stress in broccoli plants is inconsistent watering. Broccoli plants must be well hydrated. Thus, do not overwater or underwater the plants. Also, consider the stages of growth for the plant.

If it is a seedling, water regularly. After the plants have been established, only water the plants when needed. For instance, you should water frequently in hot weather but reduce the amount in cool and cloudy weather to avoid rotting the roots.

Nevertheless, water well. Regular watering will keep the soil moist consistently. At least water the plant to about an inch or an inch and a half every week. Make sure that the soil is not sopping wet as well.

Also, if your broccoli heads are developing, avoid getting them wet so that they do not rot.  Once you have made your first harvest, you can promote the growth of the second head by actively maintaining a watering schedule.

Excessive Nitrogen in the soil

Potassium, phosphorus, and nitrogen are the three essential nutrients that promote healthy plant growth. These are also the three central elements found in most fertilizers. Nitrogen is especially very essential to the growth and the yield of broccoli.

Nitrogen is important because it aids in the growth of plant tissue and leaves. It also helps the plants to become lush and green. Therefore, small amounts of nitrogen can result in plants that are yellow, withered, stunted, and unhealthy.

However, a common problem found with growing broccoli is the presence of excessive nitrogen in the soil. Too much nitrogen is bad for broccoli growth because it results in spindly growth and fewer heads.

Excessive nitrogen in the soil usually happens during soil amendment procedures such as the use of animal manure or fertilizers. Animal manure that is not fully composted has high contents of nitrogen.

How do you reduce excessive amounts of nitrogen in the soil?

Planting other plants

The best method involves planting other plants that will consume the excess nitrogen. Other plants will bind the nitrogen in the soil. Plants like cabbage, squash, and corn are especially good at consuming significant amounts of nitrogen.

Hence, grow these plants in the soil spaces that possess significant amounts of nitrogen. However, be aware of the possibility that the said plants will not be healthy. They will also lack sufficient produce. Simply use them as sponges that regulate nitrogen content in the soil.


Mulch consumes a lot of nitrogen when it is breaking down. Therefore, it is an excellent solution for soils that contain excessive nitrogen. Simply lay the mulch over the soil and it will draw out the excess nitrogen.

Particularly, use the cheap and dyed mulch since it works best. You can also use sawdust in place of mulch. Nevertheless, avoid adding excess nitrogen to your soil when gardening. You can test your soil before you plant your broccoli.


If you have been asking “why is my broccoli growing tall?” you now have the answer: bolting. Bolting will occur due to hot weather, inconsistent watering, excessive nitrogen, and late harvesting. While these factors can easily affect the growth and health of your broccoli, they can be slowed by adding more effort.

 Also, remember to use a sharp knife to harvest the broccoli as soon as they are ready. Early harvests provide tasty broccoli and it ensures future chances of good harvests. Getting a good broccoli harvest without bolting is not impossible to achieve after all. 

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