Guide to Growing Better Brussels Sprouts

Growing Brussels sprouts can be very rewarding, but also requires patience and a knowledge of the soil you are planting them in regardless if you are growing two plants in your backyard garden or growing a crop across 100 acres. Let’s explore how to grow healthier and tastier Brussels sprouts by understanding common issues and the importance of soil health and proper fertilization techniques. 

Preparing the Soil for Brussels Sprouts

Brussels sprouts are nutrient-hungry, long-season brassicas. Their roots need to stretch deep into the soil to draw up calcium, nitrogen, and other key nutrients. But without living, structured soil, they’ll struggle to access what they need, leading to stunted growth, pest problems, or bitter-tasting sprouts.

In the absence of a soil test, apply a balanced fertilizer to your soil such as GROWPRO 5-8-8 before planting to provide season-long nutrients for these hungry plants. Also, apply a biological inoculant such as Rejuvenate and BioQuest Foundation to help structure the soil and make the soil minerals more available to the plants. 

Conducting a soil test is the best way to understand what your soil lacks in terms of nutrition and biology. 

Ideal Soil Conditions for Brussels Sprouts:

• pH: 6.5 to 7.5 
• Texture: Loamy, well-draining 
• Organic Matter: At least 3-5% 
• Key Nutrients: Calcium, Boron, Nitrogen, Sulfur

Location

Brussels sprouts do best in full sun with rich, well-drained soil. Start by choosing a site that hasn’t grown brassicas in the past year or two to avoid pest and disease buildup. While encouraging sunlight, be sure there is protection from strong winds with some shelter blocking your crop. 

Your location also needs the space to plant your Brussels sprout plants at least 18 inches apart in rows that are at least two feet apart to give them ample room to grow. 

Best Time to Plant Brussels Sprouts

Brussels sprouts require between 90 to 100 days from transplant to harvest. With this lengthy timeline, it is best to start your Brussels sprouts indoors and then transplant them when ready. In northern climates like Pennsylvania, you will have to start seeds indoors in late winter or early spring and transplant when the soil temperature reaches about 50°F. In more temperate regions, a mid-summer planting for fall harvest works fine.

Fertilizers for Brussels Sprouts

Once your transplants are in the ground, the focus turns to consistent fertilization to ensure steady and healthy growth. 

Brussels sprouts will need a balanced diet of nutrients throughout their development. Conducting and referencing a sap analysis is the best and most accurate way to know your crop is healthy (or not healthy) based on those results. 

It is important to monitor for hollow stems which is a sign of boron deficiency. Monitoring calcium levels is also important because the first place that calcium deficiency impacts is inside the sprout, which can be difficult to spot. 

Also important to monitor for are flea beetles early in the growing season because they can decimate young crops when molybdenum and potassium levels are inadequate or when there is significant transplant shock. As the plant matures, monitor closely for black rot as that can infect Brussels sprouts. 

By keeping a close eye on the physical appearance of your crop and the nutrient levels, you can help prevent many of these common diseases and issues faced by Brussels sprout growers. 

All-Natural Fertilizers for Brussels Sprouts

GROWPRO 5-8-8 is a good general purpose fertilizer for gardeners looking for a balanced fertilizer for their Brussels sprouts. A general starting point for liquid fertilizers to drip irrigation is NPK (such as 7-7-7), calcium, and trace minerals. At the very least, some molybdenum should be applied, since this critical trace mineral is very important for Brussels sprouts, due to their susceptibility to aphids. Rebound Molybdenum is a great option if you need a boost in molybdenum. 

Harvesting Your Brussels Sprouts 

Sprouts are ready to harvest when they reach 1–1.5 inches in diameter, starting from the bottom of the stalk upward. Twist or cut sprouts off the stalk gently, leaving the rest to mature.

For a sweeter flavor, wait until after a light frost—cold temperatures increase sugar content and reduce bitterness.

Once the season is over, don’t forget about your soil. Plant a cover crop blend such as ReCoverIt Nitrogen Fixer to suppress weeds, and feed your soil over the winter.

Common Questions Regarding Brussels Sprouts

We compiled a list of common questions growers have while growing brussel sprouts. If one grower experiences something, it is likely others are too. 

How to Prevent Aphids from Attacking my Brussels Sprouts?

Aphids are one of the biggest challenges in growing Brussels sprouts since chemicals do not do a good job of controlling them. Aphids will crawl inside the sprout where the chemicals cannot reach them. Thus, when growing for market, it is critical to balance the soil and plant nutrients for optimal resistance to these pesky insects.

Aphids are attracted to plants with high nitrates. When plants have low brix levels or have inadequate levels of magnesium, sulfur, boron, or especially molybdenum, the plants will not convert their nitrates properly and therefore become more susceptible to these insects. 

To increase resistance, you can foliar a combination of Rejuvenate and PhotoMag. The Rejuvenate and PhotoMag combination will temporarily provide a sugar source to compensate for the low brix and at the same time also provide the critical nutrients mentioned above. 

Should I Prune The Leaves of my Brussels Sprout Plants?

Once the sprouts on the bottom of the plant are around 1” in diameter, it may be helpful to remove the bottom 6 inches of leaves. This promotes better air flow and less disease pressure. It also encourages more nutrient flow to the remaining leaves.

For more uniform growth of the sprouts, you should also consider pinching off the growing point of the plant when the lowest sprouts are around ¾ inch in diameter. This promotes more uniform growth and maturity of the rest of the sprouts on the plant.

Why Aren’t My Brussels Sprouts Sizing Up? They Grow Leaves, But Tiny Sprouts…

This phenomenon is called bolting. Bolting occurs when the plant prematurely grows flowering stems but hasn’t fully matured. Learn more about bolting and how to prevent it here.