The Brassica Episode

January 31, 2023 Angela and Mandi
The Brassica Episode
Show Notes

The brassica family includes cole crops, descendants of the mustard family and wild cabbages. This includes broccoli, cauliflower, romanesco, kale, brussels sprouts, cabbage, and collards.

(cabbage is actually a member of the mustard family- but we lump it into brassicas!)

Soil and Temperature

These crops prefer well drained soil, kept moist. The seeds require slight warmth to germinate at 65 degrees Fahrenheit or more, but prefer to grow in cool conditions. If grown in peak summer, and not provided with cooling shade, they’ll bolt. Bolting means going to seed, or sending up flower heads before a true crop is produced for harvest.

Tip: Know your growing environment! If your temperatures where you are seeding stay in the 60-70 range you may not need any bottom heat for germination. If you do use heat mats (and we do!) just remember to remove the trays when you have germination. Forgetting to do so can contribute to weak and leggy seedlings. 

When to Sow and Transplant

Sow 6-8 weeks before last date of frost in seed trays. Direct sow when temperatures are warmer. Can be transplanted out three to two weeks before last frost date when left unprotected. If row cover or a hoop house is provided, can transplant into the garden much earlier.

Tip: Grow where you have NOT grown like crops in the past couple of years- this goes for the whole brassica family. 

It is safe to generalize the statement that brassicas want a soil pH of about 6-7.

Tip: I have found over the years that crops like broccoli and cabbage enjoy a little “extra love” when the plants are in your garden and roughly 4-5 inches tall. We side dress with some well aged compost. 

Growing and Harvesting

Harvest broccoli and cauliflower when heads reach roughly 5” across, variety dependent. To blanch cauliflower heads, tie the leaves residing directly below the head together above the crown. This will blanch the cauliflower for a whiter color. According to some folks, as brussels sprouts grow, leaves can be pruned off to allow more sunlight to reach the small cabbage heads along the stalk. This is said to increase sprout size. Cabbage should be harvested before the head splits, usually at around 6” in size (again variety dependent).


  • Note the kale experiment 
  • Perennial

Troubleshooting: Any damage (usually pest related or rough handling when removing pests) to the central growing point can lead to a stunted or no head growth. The outer leaves will still grow so it may seem “okay” but they too will be tough and non-edible. 

Perennial choices exist for brassicas:

Angela purchases her’s here:

  • 9 Star Broccoli (bushing growth habit and is white like cauliflower)
  • Tree Collards
  • Walking Stick Kale
  • Daubenton's Kale
  • Kosmik Perennial Kale

Pests: Slugs, snails, cabbage moths

To deter cabbage moths, use row cover before moths appear throughout the growing season-

  1. Companion planting broccoli with garlic, chives and nasturtium helps to deter cabbage moths. Plant thickly.
  2. Mulching the garden is great but leave a small bit of soil exposed around the stem of brassicas to avoid slug and snail access

Tip: Spend 10 minutes a day with a morning tea or coffee and pick off any cabbage worms (small green worm like terrible creatures) and dispose. We also like to keep a butterfly net in garden storage to catch any you miss!