Flowering Brussel Sprout Plant? Here’s Why it Bolted and How to Stop it

The Brussels sprout (Brassica oleracea, variety gemmifera) is a biennial plant. In other words, it needs two growing seasons to reach maturity. But in those 30-31 weeks, some of these plants bolt and bloom because of the increasing temperature and day length.

Should you cut the flowers off your Brussel sprouts? The best way to stop your flowering Brussel sprout plant from bolting is by picking the mature Brussel sprouts promptly. In this way, you will also extend the harvesting season. Sometimes, you may even need to cut some of the bottom leaves, especially if no new sprouts are forming.

Why Does My Brussel Sprouts Have Flowers?

Like other biennial plants, the flowering Brussel sprout plant creates a tall seed stalk to propagate via seeds. Those yellow flowers represent the end of the plant’s life cycle as it prepares itself to generate as many seeds as possible. On the other end, people want the plant to stay in a vegetative stage to keep harvesting its sprouts.

But how does a Brussel sprout plant knows it is time to make flowers? The counter-intuitive answer is not what you may think!

As you may be aware, this plant must go through a chilly season to produce the sough-after mini-cabbages that end up on our tables. But because it reacts to low temperatures to make the sprouts, the plant also knows when the weather changes and the temperatures rise.

During the wintertime, the plant enters a stage known as vernalization. And the cold is the real reason why this plant starts flowering!

As soon as the temperature goes above 75C, the juvenile Brussel sprout plant remains in a vegetative stage. And because this is a biennial plant, the plant goes through a whole year in nature. After another cold season, the mature plant devernalizes and opens its sprouts to make seed stalks. So, it uses the cold temperature as a trigger to start flowering.

How To Stop Brussel Sprout From Bolting


The only way to stop a flowering Brussel sprout plant from bolting even more is to harvest it on time. As mentioned, a Brussel sprout plant flowers because it devernalizes. But it can also start producing flowers because of excessive stress.

A Brussel sprout plant needs two to eight weeks of cold as it vernalizes to produce flowers. But as a member of the Brassicaceae family, it requires a large amount of nitrogen to grow. On a side note, this is why, often, beginners cannot get tall plants.

On top of that, this plant likes fertile, well-drained soil rich in minerals, especially Calcium. Calcium deficiencies will result in undeveloped or burned sprouts, which do not taste as good either.

You can help the plant avoid pests and adverse conditions that may induce early flowering by:

  1. amending the soil.
  2. cutting the yellow leaves.
  3. removing any leaf that displays signs of decay. (Also, the fallen ones may attract insects and other pests)
  4. rotating your crop to keep high nitrogen levels.
  5. using plastic mulches in the wintertime to prevent water from evaporating and reduce weeds.

How To Harvest Brussel Sprouts

Flowering Brussel Sprout Plant

The sprouts are ready when they are golf-ball-size. Regarding the instructions, they are pretty simple:

  • 30-40 days before harvesting the baby cabbage look-alikes, cut the top off. (A plant takes 100 days to mature.)
  • If you want to pick the ripe ones one at a time, start from the bottom and go up.
  • If you prefer to harvest the whole plant, wait for the 100th day, pull everything out and trim the leaves to collect them.

Can You Eat Flowering Brussel Sprouts?

Some people eat Brussels sprouts raw, but it is better to cook them. For one thing, they may cause intestinal gas. But the taste changes, too. Regarding the flowers, you can add them to your salad. But first, check the flower and remove any seed!

Can you eat Brussel sprouts that have bolted? When the Brussel sprouts open up to make seeds and reproduce, the smaller leaves below the flowers remain edible and tasty. They taste like Kale or Broccoli, depending on the varieties you eat.

Because the plant is near its end, the other larger leaves get tough and bitter. Plus, the flowers produce seeds, which you can collect to later press and turn into oil. But yes, all the parts are edible, including the flowers.

2 thoughts on “Flowering Brussel Sprout Plant? Here’s Why it Bolted and How to Stop it”

  1. Thank you for this information the only question I have is that, my Brussels have grown up to 2/3foot high which is amazing especially when it is the first time growing them, we planted late last year all wS well and I got excited about seeing pea like balls growing on the stalk, now 9 months later and no veg appearing I now have a 2/3foot sprout plant looking lovley with a lot of yellow flowers, can I save my 9month old plants? This is my first full year growing veg and I am loving whatching everything grow, I live in North West of England (UK) if this helps, thank you for your time taken to read this have a lovley day and good luck gardening this year xxhelenxx

  2. Hi and thanks for this really informative video. Living in S.E. PA, and bought Burpee
    starter plants put into raised beds of mushroom soil with aged manure in Sept, but
    now (end of April) the plants (covered with tented light fabric all winter), though beautiful and lushly leaved are only 2.5 ft tall, have bolted on top and where sprouts should have grown, there are flowering stalks. Any thoughts about why there were never any sprouts at all on any of the 12 plants? Sure I missed something important, but no clue what in this first go at brussel sprouts.

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