Why Is Your Broccoli Flowering? What You Need To Know

Broccoli is an excellent source of iron, folic acid, antioxidants, fiber, Vitamin A, and minerals such as potassium. It is a cool-season, sun-loving plant that thrives in spring and fall in moderate or cooler weather. Therefore, you only have a short window for your broccoli to grow well before they start flowering.

Your broccoli is flowering due to unfavorable soil conditions, inclement temperatures, or nutrient deficiency. Broccoli naturally flowers at maturity as part of its plant cycle. However, unsuitable conditions stress the roots, causing premature flowering, a process known as bolting. 

When broccoli starts flowering, it might stop growing. Therefore, it is vital to prevent your broccoli from flowering. So, let’s take a look at the causes of flowering, how to avoid it and what you can do with your flowering broccoli.

Causes of Flowering in Broccoli

When your broccoli flowers before the heads mature, it might signal a poor harvest. There are several causes of flowering in broccoli, and they are all preventable. They include:

It Is Too Hot Outside

The primary cause of flowering broccoli is too much heat. Broccoli thrives in cool weather with temperatures ranging from 65°F to 75°F (18°C to 24°C). Therefore, most farmers or gardeners only have weeks or a few months of the best weather for broccoli. 

As summer progresses, the sun intensifies, days become longer, and the heat increases. The broccoli roots start overheating, and the plant focuses on self-preservation. Although the plants will not die off immediately after the weather exceeds 90°F (35°C), the change will affect them.

When broccoli starts flowering, the head stops growing, and the stem overgrows rapidly and produces flowers. The plant will become bitter and inedible, and your broccoli will start dying. Therefore, you must protect your broccoli plants from too much heat.

You can also plant your broccoli indoors then transplant it. You will get a head start on the planting season, and your plants will mature before the heat becomes excessive.

The Broccoli’s Soil Is Too Cold

Although it is not very common, low temperatures can cause your broccoli to flower. If your soil is less than 50°F (10°C) over several weeks, your plants will flower and ruin your chances of a great harvest. If you live in a snowy climate, you can prevent this by waiting a few weeks for the ground to thaw and the temperatures to become consistently warmer.

Your Broccoli Plant Is Stressed

Although temperature change is a stressor, several things can affect your broccoli plants and cause them to flower. These are:

  • Longer days: Broccoli plants perceive the change as summer rolls in and the days become longer. They sense the impending end of their growing season and speed up their maturity process, even if the head is yet to mature.
  • Transplant shock: It is often necessary to transplant your broccoli, but it can be stressful for the plants. Your broccoli will grow better if you transplant it before it establishes its roots. The longer you wait before you transplant the seedlings, the more stressful the move will be for the plants.
  • Lack of nutrients: Broccoli plants feed heavily on nitrogen. Lack of nitrogen and other essential nutrients in the soil affects the healthy growth of your broccoli plants.

Signs That Your Broccoli Is About To Flower

To prevent flowers, you will want to know the signs of flowering before it happens. The following are the indicators that your plants are about to flower:

  • Flowering stems: Often, flowering broccoli produces a tall stem. The stem grows very fast, quite tall, and eventually flowers.
  • Stunted heads: The heads will remain small and weak when your plants start flowering.
  • Flowering head: For broccoli with significantly large heads, bright yellow flowers will start blooming on the broccoli heads.

How To Prevent Your Broccoli From Flowering

Once your broccoli starts flowering, the main head does not continue growing. Therefore, it is crucial to prevent your broccoli from flowering and delay the process as much as possible. Here are some things you can do to keep your broccoli from flowering.

Mulch the Area Around Your Broccoli

Heat is one of the significant stressors of broccoli that cause it to flower. However, hot weather only affects broccoli when the heat reaches the roots. Mulching with thick layers of organic mulch like straw keeps the soil cool and protects the roots from excess heat.

The mulch helps insulate the soil, retain moisture and eliminate direct sunlight. It provides an additional layer that soaks up the sun and prevents the ground below from becoming too hot.

If you mulch when the weather is hot, it will keep the soil warmer in the cold season. Row covers are also an option, but they must be the kind that retains heat. Additionally, you can put cardboard below the straw to help suppress weed.

Water Your Broccoli Regularly

Broccoli does not grow well when the soil moisture fluctuates. Watering your broccoli plants frequently with cool water (not freezing) will consistently moisten the soil. The ideal weekly water amount is between 1-1.5 in (2.54-3.81 cm). 

Excess water is as harmful as insufficient water. If the water is too much and the soil is too moist, hold off for a few days and rework your watering schedule. Check on any broccoli plants you may have in containers since they dry out quicker than those in the ground.

You could also use row covers. However, get the ones that reduce the amount of sunlight and heat, not those that retain it.

Transplant Your Broccoli Early

The best way to protect broccoli roots from too much heat is to plant seedlings early. However, do not plant too early because the excessive cold will kill your plants. Wait for all the risk of frost to pass before you plant. You can grow the broccoli indoors and transplant it later to gain an advantage ahead of the season.

If your broccoli starts indoors, transplant it before it establishes and binds its roots to the pots. The ideal seedling size to transplant is 2.5 inches (7 cm). If the delicate seedlings cannot withstand erratic weather, you can move them to bigger-sized pots until the right time for transplanting them.

After transplanting, provide extra nutrients to help your plants adapt to the new environment. 

Keep the Soil Fertile

Plant your broccoli in healthy soil to help it grow fast and develop deep roots before the weather becomes too hot. 

Before planting, mix in some compost or other rich organic material to improve the soil. Use a test kit to check the nitrogen levels in the ground. If the nitrogen is insufficient, add blood meal and mix with the soil before planting.

After transplanting your seedlings, wait three weeks before adding high-nitrogen fertilizer to the soil. When the heads begin to form, add liquid fertilizer such as fish emulsion or any other type with high nitrogen and low phosphorus concentration. 

After harvesting the main head, apply more fertilizer to help properly form side shoots and smaller heads. If using containers, your broccoli will need fertilizer frequently since the soil retains fewer nutrients than an in-ground garden. 

Follow the manufacturer’s guide whenever you add any fertilizer because excess nitrogen loosens broccoli heads.

Create Shade

No vegetable can thrive without any sunlight. Broccoli needs a minimum of six hours of daylight daily. Look for a spot that receives this much sun or an airy, well-lit space that receives indirect or reflected light most of the day. 

Creating shade will protect your broccoli from too much direct sunlight that often triggers flowering. You can use netting, shade cloth, row covers, or plant taller plants around your broccoli. Tall, leafy plants like asparagus and zucchini will provide the necessary shade for your broccoli.

Sow in Succession

You can plant a few seedlings every week instead of sowing all of them at once. Varying the planting time means that hot weather will find your broccoli plants at different stages of growth. Therefore, they will react differently to the warmer temperatures, and you can prevent losing your entire harvest to flowering.

Plant Bolt-Resistant Varieties

Several broccoli varieties resist bolting. Growing the bolt-resistant variants is an excellent option if you think your broccoli will not be ready when the summer heat checks in.

You can choose a heat-resistant variety that will not flower during hot weather. Another option is to plant a fast-maturing variety that will grow and mature in its season.

Harvest Frequently and Early

Broccoli grows new side shoots every time you harvest the head. Unlike the head, the side shoots do not flower quickly. As the hot summer months approach, consider an early harvest of your broccoli heads before they flower. This way, you will still have a chance to harvest the regrowth.

Watch out for tiny yellow flowers or opening buds. Pick the crowns before the flowers bloom in full on your broccoli heads.

Use Row Covers

In most cases, broccoli will do well without much protection. However, it sometimes needs shielding from the elements. Since broccoli grows best in cool climates, unexpected freeze or heat waves can damage the plants.

Installing row covers will protect your plants and the soil from direct sunlight, heat, or frost. They will also keep your plant productive for longer. Although they may slow down the maturation process, they significantly affect the soil temperature and keep the plants from flowering when the weather becomes too warm.

Cover your broccoli with row covers if temperatures are about to dip for extended periods. Cover the plants overnight with a floating row cover if the cold wave will be brief and only for an evening.

What To Do With Flowered Broccoli

Once your broccoli starts flowering, your hopes of a great harvest diminish. However, all is not lost as there are several uses for your flowering broccoli. These include:

  • Make a salad: Fortunately, all parts of broccoli are edible, though not all of them are as delicious as the head. Cut off the flowers and add them to a salad or eat them raw.
  • Harvest: You can harvest it if the head is slightly mature and has not wilted yet. You might end up with a small and bitter harvest, but it is worth trying. If you get to it early, it could be tasty.
  • Allow it to regrow: Once you remove the flowers, the side shoots might continue growing, though they will be smaller. Keep providing your plant with suitable conditions and caring for it if it is still growing.
  • Collect seeds: Instead of removing the flowers, you can leave them to attract bees for pollination. You can also wait until the flowers become seed pods and dry, then you collect seeds to plant in the next season.

What You Need To Know Before You Grow Broccoli

Broccoli is a versatile vegetable for home cooking and packs rich amounts of vitamins A and D. When planting, you will want to grow full, healthy heads that do not flower too soon and lose their flavor. Here are some things you need to know about cultivating broccoli to increase your chances of a bountiful harvest.

Plant Your Broccoli in the Fall

The secret to healthy, great-tasting broccoli is the planting season. Broccoli flourishes in cool weather and produces healthy, sweeter heads than those that grow in other seasons. You can plant broccoli in either fall or spring, but the best season is in fall because weather conditions during spring are unpredictable. 

Long, cold springs cause young broccoli seedlings to form small heads. 

If temperatures rise in early spring, the broccoli suffers heat stress and flowers prematurely. Premature flowering makes the heads harder and bitter with small, less palatable florets. If you want your broccoli plants to last in the later spring or summer, plant a heat-tolerant variety that can withstand the summer heat.

You can calculate the best time to plant your broccoli during fall. Plant seeds between 85 and 100 days ahead of the anticipated first frost in the fall if you grow them in the garden

If you use transplants, check the number of days before maturity for that variety and add ten days. To get the ideal time to plant, count backward from the anticipated date of the first fall frost.

Plant Your Broccoli in Fertile Soil With Full Sunlight

Growing healthy broccoli requires full sun and fertile, well-drained, consistently moist, slightly acidic soil. 

Organic matter and the proper pH, ranging from 5.8 to 6.5, ensure a steady supply of essential micronutrients such as boron. A soil test is also necessary because boron deficiency causes hollow stems in broccoli, while excess boron is toxic to the plant.

There are specific spacing conditions for planting broccoli in the fall. If you are growing on a raised bed, the plants need a spacing of between 15-18 in (38.1-45.72 cm).

For rows, the seedlings should be between 18-24 in (45.72-60.96 cm) apart. Row spacing should be 24-36 in (60.96-91.44 cm) to allow room for watering, weeding, fertilizer, and harvesting. Plant the transplants deeper in the soil in the garden than you did in the pot.

Use The Proper Fertilizers For Broccoli

Before planting, mix the soil with a coating of aged manure or a 2 to 4-inch (5.08-10.16 cm) layer of rich compost because broccoli is a heavy feeder. Rabbit manure is an excellent choice, but compost or aged manure will still produce big, tasty heads.

After harvesting the main head, add some nitrogen-rich fertilizer like fishmeal to stimulate the growth of side shoots. You can also add tagged manure to the soil around the base of the plant.

Keep Your Soil Healthy To Prevent Pests

While row covers may provide a buffer against pests, the best protection is healthy soil. Well-balanced, nutrient-rich soil will keep pests away and help your plants to thrive. Additionally, infestations are usually more common in spring than in fall.

The two types of pests that primarily affect broccoli are aphids and cabbage loopers. Aphids often hang on the underside of leaves and cause yellow, curled, or deformed leaves. If the pests are on a few leaves, remove and dispose of them. 

If the aphids are widespread, you can knock them off the leaves with a powerful spray of water. Another remedy for aphids is to use insecticidal soap. However, you have to use the soap multiple times since it is only effective against aphids that are active when you use it.

Cabbage loopers destroy plants by nibbling large holes in the leaves. If your broccoli suffers an attack of the loopers, the easiest way to remove the caterpillars is to remove them physically. You can also cover the plants with a thin net to keep the caterpillars at bay. 

If physical removal does not work, bacillus thuringiensis var. Kurstaki will solve the problem. This naturally occurring bacteria will stop the pests from eating away your plant but is safe for beneficial insects.

Protect The Broccoli From Cold Temperatures

Exposing broccoli to freezing temperatures causes chilling injury. The buds turn purple, and the heads might soften, though they remain edible. You could still thaw and enjoy frozen broccoli, but you should not leave heads to freeze and thaw constantly.

Get floating row covers to protect your plants from cold weather and provide extra heat. The covers will shield your harvest from heavy freezing and extend the growing season to four weeks longer. You can also protect your broccoli with a cold frame or tunnels, which increase daytime temperatures by up to 30º F (16º C).

Harvest Your Broccoli Promptly

Broccoli takes approximately 85 to 90 days to form the first head. To retain the flavor, harvest your broccoli heads when the buds start swelling before yellow flowers start showing. Watch the head closely because the buds start flowering as soon as the head begins spreading open.

Harvest the central head by cutting off the stem at an angle between 5-8 in (12.7-20.32 cm) from the head. This cut enhances the production of side shoots for more harvest. The side shoots are sweet and tender, and you do not have to wait until the main heads are large. Harvest the small heads while they are tight and firm.

You can harvest broccoli several times during the growing season. Generally, you can harvest broccoli up to three times within three months. However, how long you can gather your plants will depend on the elements. In cool weather, you can harvest broccoli repeatedly. In hot weather, the plants become unproductive.

Does Broccoli Regrow After Flowering?

Broccoli does not regrow after flowering. Some parts might continue growing, but they will not be as productive as you would like. After flowering, the main head becomes bitter, begins to wilt, and stops growing.

Usually, broccoli plants have smaller heads known as side shoots. These shoots grow around the central head and can sometimes continue growing after the plant flowers. However, they do not grow big, and the harvest will be smaller than the main head. Also, they often become bitter.

While parts of a broccoli plant continue growing, the main plant does not grow after flowering. Once it flowers, growth stops because the plant focuses its energy on producing flowers and seeds.

Is Flowering Broccoli Edible?

Flowering broccoli is edible. If the buds on your broccoli are still tight, you can snip off the few flowers present, then prepare your broccoli as usual. The bright yellow flowers are also edible and tasty. They have a mild, pleasant flavor and some high-end food markets sell them as a delicacy.

The natural growth cycle of a broccoli plant progresses from flower buds to blooms to seeds. The leaves, tender stems, and the unopened buds that form the head are the edible parts.

The edible buds bloom into yellow flowers if you do not trim them for consumption. These flowers attract small bees and a host of other pollinating insects. After pollination, the flowers produce seeds.

If you do not harvest your broccoli in its tight bud stage, go ahead and harvest it even with blossoming flowers. You can use them as an attractive addition to your salad or an edible garnish in other dishes. Completely open flowers wilt and lose their texture when steamed, while partially open buds do not change shape. 

You can eat broccoli flowers cooked or raw. However, they do not appeal to everybody’s palate. Some people enjoy the distinctive texture and enjoy the nutty flavor, while others describe them as grainy and bitter.

Unfortunately, letting your broccoli flower has a downside. Once it blooms, it loses its nutritional value. Eating it does not provide the same health benefits as eating regular broccoli. 

Final Thoughts

It is sad to watch your broccoli start to flower before you harvest it. Fortunately, now that you know the signs of a broccoli bloom, you will be able to recognize any signs that your plant is about to start flowering and harvest it before it’s too late.

Be sure to keep an eye on your broccoli, fertilize it, and monitor the outdoor temps to prevent flowering. If you follow these instructions, you’ll be enjoying flowerless florets all season!

Alexander Picot

Alexander Picot is the principal creator of TheGrowingLeaf.com, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

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