Growth Stages of Brussel Sprout Plants

When many people think of brussel sprouts, they think back to childhood when their parents forced them to eat that round, green vegetable.

However, most of us that gave them a second chance in adulthood have found them to be a savory, nutritious dish that can be cooked in numerous ways.

Although we all know what brussel sprouts look like on our plate, how do they get there from a seed?

Life Cycle of Brussel Sprouts

Beginning Stages

Brussel sprouts propagate through seeds, and require soil temperatures between 45 – 85⁰F to germinate. They prefer a soil pH of 6.0-7.5 and to grow in an area of full sunlight and abundant moisture.

Sprout seeds typically take between five to eight days to germinate after being planted. After germination, the seed begins to grow a taproot and stem in order to obtain more water and nutrients and to reach for sunlight.

The first two leaves that grow from the stem are called the “seed leaves” or cotyledon. These first leaves enable the plant to gather sunlight and convert it to energy through photosynthesis.

The next leaves that grow out from the stem will be “true leaves” and are the shape that the rest of the leaves on the plant will be.

Vegetative Growth

The heads of the brussel sprouts continue to fold onto each other until they have fully formed, where they then loosen up to make room for the seed stalk to develop.

There are specific conditions needed for this action to be performed: certain temperatures, daylight and growing conditions that are different for each variety of brussel sprout.

Once the seed stalk begins to form, the plant will shoot up in height and flower at the top, reaching two to three feet. On the seed stalk, what we refer to as the brussel sprouts begin to form and mature. These sprouts grow on the stalk until they are about one to one and half inch in diameter and ready for harvest.


Brussel sprout plants reproduce through seeds, which require sexual reproduction. The flower that the plant grows needs pollination from insects or pollen in the wind. Brussel sprouts and other plants in their family can be direct-seeded or transplanted, with the ladder being the preferred method, in order to ensure germination under optimal conditions.

Dormancy and Second Year Growth

Brussel sprouts are biennial crops, which means that they will continue to grow for up to two years. Most gardeners and commercial growers grow the crop as an annual. In order to efficiently harvest the second growing season, “bolting” will have to be properly managed.

“Bolting” is when a premature seed stalk grows in the first year and flowers before the plant is ready to produce a proper crop yield. “Bolting” can be managed by planting at the appropriate time for your area, reducing environmental stressors, and planting seeds with sufficient spacing and plenty of fertilizers.

Do Brussel Sprouts Keep Producing?

The most efficient way to harvest brussel sprouts is by successive harvests of individual sprouts. The best way to do this is by removing the lower leaves and starting to pick the sprouts off starting at the base and making your way to the top as they mature.

If you are harvesting in a colder climate, then sprouts will grow until the temperatures are too cold; while if you are harvesting in mild climates then the plant will grow sprouts longer.

During this grow trial in Santa Clara County, California, brussel sprout plants were planted in April and then harvested 6 times total with the last harvest coming in February, 10 months after the planting date.

When To Plant Brussel Sprouts

The most optimal time to plant brussel sprouts is in the late-spring to early-summer season, about 90 to 100 days before the first frost time in the area. This is due to the plant prefering to grow in cooler temperatures, so those planted during this time will mature with better quality sprouts during the fall when temperatures start to decline.

Sprouts that mature during hotter weather are more likely to be bitter, while those that mature during frost improves flavor. If you are planting in the United States, summers in most areas of the country will be too warm for a quality product.

However, there are some newer hybrid brussels sprouts varieties that have a shorter than traditional growth period and prefer maturing in warmer than usual conditions.

When considering where to plant brussel sprouts, research has shown they prefer sandy loams for early crops and silt, silt loams and clay loams for late crops.

Interesting Facts About Brussel Sprouts

  • Brussel Sprouts, or scientifically named Brassica oleracea, are part of the broccoli family, along with cabbage, cauliflower, and kohlrabi.
  • Although the origins of the tasty vegetable are uncertain, it is widely believed they originated in Brussels, Belgium– hence brussel sprouts!
  • The vegetable is widely common in Europe, esspecially in the Netherlands where they annually grow 82,000 tons.
  • Current research shows that the chemical sulforaphane found in brussel sprouts can help with preventing certain types of cancers.
  • They have cholesterol benefits as well; when steamed, the fiber in the brussel sprouts combines with the bile acids in the digestive track. This allows the bile acids within you to be excreted more effectively, which lowers your overall cholesterol level.
  • They are also high in protein, fiber, potassium, and even vitamin C and A. One cup of brussel sprouts has four times more vitamin C than a cup of orange juice!
  • Not only are they nutritious, but they contain a lot of energy as well. One cup of Brussel sprouts contains 158 kJ of energy which can be translated as 44 watts per hour.
  • In 2015, a group of scientists in London worked with school children on an experiment to really show off how much energy these little sprouts have inside them. They harnessed the energy of 1,000 brussel sprouts and converted that energy to power the lights on a Christmas tree!

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