Brussels Sprouts are a member of the Brassica family, making them a relative of cauliflower, broccoli, and cabbage. They are often referred to as mini cabbages, since the plant looks like many small cabbages growing on a stalk. Like other members of this family, Brussels sprouts are a cool season crop that thrives in cooler temperatures. This beloved vegetable is a biennial plant, which means that it will come back for a second season to finish its full circle of development. However, it is typically grown as an annual instead. In this article, we will discuss both seasons of the Brussels sprouts growing stages, so you know what to expect as your plant goes through its lifecycle. These strange looking plants are quite rewarding to grow, so test your green thumb with Brussels sprouts this season!
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What are the Brussels Sprouts Growing Stages?
The Brussels Sprouts growing stages are germination, seedling stage, vegetative growth, sprout development and harvest. The second season of the Brussels Sprouts lifecycle will consist of bolting and seed production. Each stage of growth marks a unique time during development and is essential to the plant’s overall success. Understanding the different stages of development will provide you will helpful insights into your plant, allowing for optimal growth and harvests!
The Germination Stage
After you select your variety of seeds, you will be able to start growing them. Germination will occur once the planted seed absorbs moisture, which will soften the harder outer shell. This will allow for water and nutrients to be taken in and a small stem with two leaves, called cotyledons, to emerge. This small stem and leaves will grow upward toward the light until they each the soil’s surface.
You should start Brussels sprouts seeds indoors 4 to 6 weeks before the last frost date occurs in your area. This will give your plant extra time to develop for a longer growing season. Germination will typically occur within one week but may take two. The optimal temperature for germination of this plant will be between 45°F to 85°F.
The Brussels sprouts seedling stage begins as the small leaves and stem break through the soil while reaching toward the light above. The seedling will continue to grow, as true leaves begin to be produced. True leaves are the leaves that grow after the first set of baby leaves. They are larger and will have a more typical Brussels sprout leaf appearance. The roots underneath the surface will continue to grow and expand, anchoring the plant into the soil.
During the seedling stage, it is important that plants get adequate water and sunlight. You should keep the seedling’s soil moist and ensure the plant receives at least 6 to 8 hours of sunlight per day, optimally more. Once the risk of frost has passed, you can move the plants outdoors. Don’t forget the hardening off process in order to slowly acclimate the plants to the outdoor environment. The seedling stage is the most vulnerable stage of the plant, so be sure to protect it from any damage.
Tip: Be sure to space your Brussels sprouts properly according to your seed packet. This plant can grow quite large and bushy and will require adequate space for growth.
Vegetative Growth Stage
The vegetative growth period of the Brussels sprouts growing stages is a time of significant development for the plant. During this phase, the plant will focus all of its energy on developing new leaves and lengthening its main stem, while increasing its overall size. You will see the plant begin to grow a lot of large leaves as the plant grows taller. The average height of this plant will be 2 to 3 feet tall. The large leaves help the plant capture energy from the sun during photosynthesis, as well as provide shade for the upcoming sprout growth. The roots will continue to develop under the soil to adequately anchor the plant into the ground and provide proper nutrient and water uptake.
Fertilizing with a nitrogen rich fertilizer is important during this stage since the plant is using a lot of energy to produce foliage. You should do this once every 3 to 4 weeks. It is important that a Brussels sprout plant receives adequate water during this stage as well, especially during hot temperatures. The plant should get 1 to 2 inches of water per week. Utilizing mulch around the base of the plant will help the soil retain moisture.
Tip: Brussel sprout plants often require additional support due to their height and growth pattern. Staking them is recommended.
Sprout Development Stage
The sprout development stage is an exciting part of the Brussels sprouts growing stages, as this is when you finally get to see the edible portion grow. The plant shifts into putting the majority of its energy into the growth of the Brussels sprouts at this point. You will begin to see small buds start to form along the main stem, right next to where the base of the leaves connect. These small buds are called axillary buds due to their growth occurring in the leaf axils of the plant. They will slowly grow larger and larger, with tightly packed leaves. Each small bud will form into its own individual sprout that can be consumed.
It’s important to not apply too much nitrogen to the soil during this stage because it can impact the growth of the sprouts. Too much nitrogen can cause the sprouts to be of poor quality, loosen, or split.
Tip: If the sprouts on your plant are not growing well, this may be due to too much heat or inadequate water or nutrients within the soil.
The harvest stage is the most rewarding period of the Brussels sprouts growing stages, where you can finally pick some of your hard earned vegetables and taste them! This stage marks the completion of the sprout’s growth on the stem. Since the sprouts will mature at different rates, the harvest stage will typically last for multiple weeks. The sprouts on the bottom of the stem are typically the first ones to begin to develop. Therefore, they are usually the first ones that are ready to harvest. Brussels sprouts will be ready for harvest when they are:
- 1-2″ in diameter
- Bright green in color
Once the Brussels sprouts are ready for harvest, gently grab onto one and twist it off of the main stem. Alternatively, you can cut it off of the main stem with a knife or garden shears. If left on the plant for too long, the small heads will begin to turn yellow, become tougher and not taste as good.
Tip: The taste of the sprouts are enhanced when they experience cooler temperatures, so light frosts can make them taste sweeter.
Since Brussels sprouts are a biennial vegetable, they will come back for a second year. The plant does not produce edible Brussels sprouts in the second season like it did in the first year. The second year will consist of bolting and seed production. If you want to collect seeds from your Brussels sprouts, allow the plant to continue to the next season. People often opt to dig them up after the first year and are therefore, usually grown as if they are annuals.
Bolting is where the plant begins to focus on reproduction rather than sprout growth. When a Brussels sprouts plant is ready to bolt, a flowering stalk will shoot up from the center of the plant. This will have many buds that will open into flowers. The flowers will need to be fertilized by pollinators or from the wind. Once this occurs, the seeds will develop and mature within the pods.
The final part of the Brussels Sprouts growing stages is seed production. Once the flowers have been fertilized and the seeds have matured, the seed pods will dry out. At this point, you may collect the pods to harvest the seeds for future use.
Brussels sprouts. Cornell University