Zone 9 · Brassicas Growing Guide

When to Plant Brussels Sprouts
in Zone 9

The most patient brassica — needs cold to form tight buttons. Flavour dramatically improves after frost. Definitely a fall crop.

Plant outdoors
Sep – Oct
Start indoors
Jul – Aug
Last Frost
~Jan 31
Days to harvest
90–110 days
Difficulty
Hard
Ready to harvest — Zone 9
Harvest window: Dec – Mar

Planting Calendar

In Zone 9, Brussels Sprouts should be planted outdoors Sep – Oct, after the average last frost date of approximately Jan 31. Start seeds indoors around Jul – Aug for a head start.

Fall/winter crop.

Care Guide

Sunlight
Full sun · 6–8 hrs/day
Watering
Regular
Spacing
18–24 inches
Soil
Rich, fertile, well-draining
Days to maturity
90–110 days
Soil pH
6.0–7.5
plant tip · Zone 9

Fall/winter crop.

Feeding Schedule

How often
monthly
Feed type
high nitrogen then balanced
Key timing
switch to balanced when sprouts form

Long season crop. Feed monthly. Avoid excess nitrogen late season or sprouts will be loose and leafy.

Companion Planting for Brussels Sprouts

What you plant next to brussels sprouts makes a real difference — some plants actively help, others compete or attract pests.

Grows well with
  • Celery
  • Onions
  • Hyssop
Keep away from
  • Tomatoes
  • Strawberries
  • Fennel

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Common questions

In Zone 9, brussels sprouts is a fall-planted crop. Plant outdoors Sep – Oct once temperatures cool in autumn. It overwinters and is ready to harvest around Dec – Mar. No last frost consideration — plant before the ground freezes.
Zone 9 has an average last spring frost of approximately Jan 31 and a first fall frost around Dec 15. These dates vary by specific location — use your ZIP code in the plant app for precision based on the nearest NOAA weather station.
Good companion crops for brussels sprouts include Celery, Onions, Hyssop. Avoid planting near Tomatoes, Strawberries, Fennel, which can compete for nutrients or attract pests.
Brussels Sprouts typically takes 90–110 days from transplant or direct sow to harvest in Zone 9. Expected harvest window: Dec – Mar.

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Brussels Sprouts in other zones
Crop Guides