How to Grow Brussels Sprouts

Published December 4, 2019
Stalk Of Brussels Sprouts

Brussels sprouts are easy to grow when you know how and when to plant them. This cabbage family member is chocked full of vitamins and protein.

When to Grow Brussels Sprouts

One of the biggest mistakes many people make when first trying to grow Brussels sprout (Brassica oleracea var. gemmifera) is to plant for a summer crop. Just like any cabbage, Brussels sprouts is a cool weather crop.

Time to Plant Tasty Brussels Sprouts

Since Brussels sprouts has a long maturation period of 80-100 days, depending on variety. Planting them in the spring is not feasible for zones with long growing seasons and summer heat. Depending on your hardiness zone, you may be better off waiting to plant Brussels sprouts in late summer so the buds will be ready to harvest in late fall or early winter.

Calculate Planting Time Backwards

You'll need to calculate your planting time by counting backwards from your typical first frost in the fall. You will then step back from that date four months (80 days growing period).

When to Plant in Zones With Short Growing Seasons

If the growing season is short for your hardiness zone, you can plant Brussels sprout indoors about three weeks before the typical last spring frost. This will give you a broader window of growing time, enough to allow the buds to mature and go through at least one frost.

Snow on Brussels sprout

How to Grow Brussels Sprouts

Now that you know the proper timetable for planting, you're ready to get your supplies together. You may wish to start seedlings indoors and then transplant. You can easily direct sow in a raised bed or row garden. However, Brussels sprouts fair better in a raised bed since you'll be allowing the plants to continue to grow into the cold-season growing period.

Start Brussels Sprouts Indoors

If you live in a region with a short growing season, you may benefit by planting seeds indoors on 3-4 weeks before the last frost date in the spring.

  1. You will need a planting tray divided into individual cells.
  2. Fill each cell with seed soil mix.
  3. Plant two seeds per cell.
  4. Plant seeds ½" deep.
  5. Water after planting.
  6. Keep soil moist.
  7. Use a grow light.
  8. Plants need 8 hours of darkness each night.
  9. You can use a heat mat to stimulate germination.
  10. When the second set of true leaves emerge, you can fertilize with diluted solution (one-half normal strength).
  11. Use diluted fertilize once a week.
  12. Seedlings are ready to transplant when they are 5"-6" high.

Harden Off Brussels Sprouts

You'll need to harden off the plants before you can transplant them. This will take about a week.

  1. Set the plants on a flat surface underneath a tree or other shaded area.
  2. You'll leave the plants protected in the shade for two hours and return them inside under the grow light.
  3. The next day increase the time to four hours.
  4. On the third day you can put the tray of seedling in the sun for 30 minutes, expanding the next day to an hour.
  5. Continue to increase the amount of time in the sun until you can leave the plants out all day and night.
  6. Your plants are ready to be transplanted into a container/pot, raised bed or row garden.

How to Transplant Brussels Sprouts in a Container

The best size container for a single Brussels sprout is a 5-gallon container that is at least 12" deep. A 14" diameter is an ideal sized container. Set one plant per container.

  1. If you're planning a container garden for your Brussels sprouts, fill the container with potting soil.
  2. Make a well in the soil for placing the plant using your hands or a handheld cultivator.
  3. You will remove the plant from its cell, by inserting a pencil or screwdriver into the hole and pushing gently to ease the plant from the cell.
  4. You can support the plant by grasping the leaves to lift it from the cell. This will prevent you from accidentally damaging the plant stems where the buds will form.
  5. Place the plant roots first into the hole and fill with soil until the roots are covered and the soil surrounding the plant is level with the rest of the soil in the container.
  6. Press the soil around the plant with your hands pressing firmly, but gently to anchor it in the container.
  7. Water thoroughly and let the plant rest and adjust to its new home. Continue to water enough to keep the 1"-2" top layer of soil moist.

How to Transplant Brussels Sprouts in Raised Bed

If you're using a raised bed to grow Brussels sprouts, you can transplant them the same way you did with the container. Square-foot gardeners will put one plant per square.

  1. Remove the plants from the cells, using a pencil to push them free of the cell.
  2. Support the plant by gently grasping the leaves to protect the stem.
  3. Dig a hole in each square of the raised bed.
  4. Place the root ball into the hole while holding the plant by the leaves as you fill it with soil.
  5. Pat the surface firm with your fingers around the plant to anchor it in the bed.
  6. Add mulch around the stem.
  7. Water in a slow flow to soak the soil surrounding the plants.
Brussels sprout stalk

How to Transplant Brussels Sprouts in Row Garden

Once you have laid out your rows with a tiller, you can transplant the Brussels sprouts. Use the same method as the container, except you'll be planting the seedlings in a row, spaced 18" apart.

  1. Remove the plants from the cells, using a pencil to push them free of the cell.
  2. Support the plant by gently grasping the leaves to protect the stem.
  3. Dig a hole in the row using a trowel.
  4. Place the root ball into the hole while holding the plant by the leaves as you fill it with soil.
  5. Pat the surface firm with your fingers around the plant to anchor it in the bed.
  6. Add mulch around the stem.
  7. Water in a slow flow to soak the soil surrounding the plants.

How to Direct Sow Brussels Sprouts in a Raised Bed

To prepare your garden bed, you can add compost to the soil a couple of weeks before transplanting or direct sowing. Compost with a high nitrogen content is recommended. Don't use fertilizer since it will burn and kill the seeds.

  1. Double plant so you have two seeds per square (you'll later thin out the weaker plant).
  2. Plant seeds ½" deep.
  3. Water with a slow flow so you don't dislodge the seeds.
  4. Keep the soil moist but don't over water, since it can make the seeds rot.
  5. When plants are 6"-7" high, thin by discarding the weaker plant.
man sowing seeds in vegetable garden

Direct Sow for Row Planting for Brussels Sprouts

You will follow the same steps for direct sowing in a raised bed, only you'll space the seeds 3" apart. Once the plants are 6"-7" high, you'll need to thin them so you have one plant every 18".

Direct Sow in a Container

You will follow the same method as the sowing in a raised bed. In a few months, you'll have a tall robust Brussels sprout.

Care and Maintenance of Brussels Sprouts

Brussels sprouts take a long time to mature. You can help your plants to mature by watering and fertilizing them regularly.

  • Sun: Full sun is required for a minimum of 6 hours each day.
  • Mulch: Add mulch 1"-2" thick, around plants in a 2"-3" in diameter.
  • Soil: Use well-drained soil high in organic material with a slightly acidic pH of 6.8.
  • Water: Keep the soil moist with regular watering. Don't allow soil to get dry or over water.
  • Staking: You'll need to stake the plants when they get top heavy.
Man Holding Stalk Of Brussels Sprouts

How to Fertilize Brussels Sprouts

This heavy feeder needs to be fertilized using a high nitrogen fertilizer every 4 weeks. This plant enjoys a side dressing either placed on top of soil 3" from the plant stem. You may prefer to dig 2"-3" out from stem 3" deep to bury the fertilizer, so it can slowly leach down to the roots.

Harvest Before Temperatures Drop Drastically

You want to harvest before the temperature drops 20°F and below. You can tell when the plants are ready to harvest since the bulbs will become firm to the touch.

A Frost or Two Sets Flavor

You want at least one frost before you harvest since the shock of the cold gives the edible buds, the sprouts, an almost sweet flavor. The cold temperature forces the Brussels sprouts to release sugars that soften the natural bitter taste.

Knowing When to Harvest Brussels Sprouts

You will need to pinch the top of the Brussels sprout plants when they are between 18"-20" tall. At the same time, you need to cut off what is known as the terminal bud. This is located at the very top of the stalk. Cutting off the terminal bud will prevent the plant from continuing to grow in a upward direction and reroute that energy to form sprouts.

Prune As You Harvest

You will harvest the sprouts by twisting them to break off of the stem. You will need to prune your plants when you begin to harvest the buds. Cut the lower leaves from the bottom part of the plant as you harvest.

Learn How to Successfully Grow Brussels Sprouts

Once you understand the life cycle of Brussels sprouts, you can determine the best way to grow these small cabbages in your garden. If you follow the instructions, you'll be enjoying an abundance of Brussels sprouts well into your next bumper crop!

How to Grow Brussels Sprouts