Brussels sprouts are cool-season crops that are typically grown in the fall, winter, and early spring.
When to plant brussel sprouts
The best time to plant brussel sprout seedlings outside is in late spring/early summer, about 100-130 days before the first expected frost. This means starting the plants by seed indoors and then moving them out. In most regions, this means planting them in about mid-June.
We would expect to harvest Brussels sprouts by about mid-September in our zone 5 climate. These plants are part of the Cabbage family most of which love to grow cold in the spring but Brussels sprouts need to finish cool for best results. This can be tricky in hot climates.
How to plant brussel sprouts
Here are the steps for planting Brussels sprouts:
Go to a reliable garden center and ask about growing Brussels sprouts in your area and if they can recommend the best varieties to try. In hot climates, it is good to select heat-resistant varieties.
Count backward based on the total days to harvest for your variety as indicated on the package and plan to seed your plants indoors at about the right time to get in a harvest by about mid-September. This is usually about mid-May to plant seeds.
Follow my seeding indoors guidelines to have the best success.
Ken’s seeding indoors guidelines
Use high-quality seed: Make sure to use high-quality seed that has been stored properly. Old seed may not germinate well, so make sure to use seed that is within the recommended storage time.
Plant at the right depth: Make sure to plant the seeds at the right depth. Most seeds should be planted at a depth of about twice their diameter. Check the seed packet for specific planting instructions.
Keep the soil moist: Keep the soil moist after planting the seeds. This will help to ensure good seed germination. Make sure to water the soil regularly, but avoid overwatering, as this can lead to seed rot.
Check the temperature for seed germination: Most seeds prefer a temperature of about 78°F, but some may require slightly higher or lower temperatures. Check the seed packet for specific temperature requirements. Use a seedling bottom heat mat for fast germination and get the seedlings off the heat once most have germinated.
Check if your seed needs to be pre-soaked before planting.
Use a small fan over your seedlings to prevent diseases and mimic the real world.
If your seeds keep drying out cover your flat with kitchen wrap or a clear plastic lid that comes with many seedling trays, for a day or two to get the seeds going but don’t leave it too long as the seeds will mold.
Transplanting brussel sprout seedlings
Once the plants are up and ready to plant out, (should be about mid-June) choose a sunny location with well-draining soil. Brussels sprouts prefer slightly acidic soil with a pH between 6.0 and 6.8.
Prepare the soil by adding compost or aged manure to improve soil fertility and texture. Brussels sprouts require rich, moist soil to grow well.
If direct seeding into the garden, sow the seeds about 1/4 inch deep and 1 inch apart. If starting the seeds indoors, transplant them into the garden when they are about 4-6 weeks old and have developed several leaves.
Space the plants about 18-24 inches apart in rows that are 2-3 feet apart.
Caring for brussel sprouts
Water the plants regularly, keeping the soil consistently moist but not waterlogged.
Fertilize the plants with a balanced fertilizer every 4-6 weeks throughout the growing season.
Pest and disease issues
Brussels sprouts are susceptible to a number of pests and diseases. Common pests include aphids, cabbage loopers, and cabbage worms, while common diseases include clubroot and black rot.
To prevent these issues, it is important to practice good garden hygiene, including rotating crops, removing any plant debris, and keeping the garden weed-free. In addition, you can use organic pesticides and beneficial insects, such as ladybugs and lacewings, to help control pests. I highly recommend covering the plants with insect mesh to keep the bugs out right from the start.
Soil amendments
Grow brussels sprouts in rich, moist soil to achieve success. To improve the soil, you can add compost, aged manure, or other organic matter to increase soil fertility and improve soil texture. In addition, you can add lime in rainy areas or sulfur in dry arid areas to adjust the soil pH to the preferred range of 6.0 to 6.8.
Before you go…
In summary, planting Brussels sprouts in mid-June in a sunny location with well-draining, slightly acidic soil and regular watering and fertilizing will result in a successful crop. It is important to practice good garden hygiene to prevent pest and disease issues and amend the soil with organic matter and adjust the pH as needed. When people ask me when to plant brussel sprouts I always respond “When the soil is comfortable to the bare bottom!”