If you’re gardening in zone 9, figuring out when to plant cabbage is your first step to a great harvest. The optimal timing for planting cabbage in this warm climate is all about avoiding the summer heat.
You have two main windows: a fall planting and a late winter planting. Getting these dates right means your cabbage will mature in the cool weather it loves, leading to crisp, sweet heads instead of bolting or poor growth.
When to Plant Cabbage in Zone 9 – Optimal Timing for Planting
The key to success in zone 9 is understanding that cabbage is a cool-season crop. It thrives in temperatures between 60°F and 70°F. Your goal is to schedule planting so the heads develop during these cooler periods, not during the hot summer.
Fall Planting: Your Primary Season
For most zone 9 gardeners, fall is the best and easiest time to grow cabbage. The season offers a long, cool period for growth.
- Start Seeds Indoors: Begin your seeds about 10-12 weeks before your first expected fall frost date. For many in zone 9, this is late July to early August.
- Transplant Outdoors: Move your seedlings into the garden 6-8 weeks before the first frost, typically from late August through September. The soil is still warm, which helps with establishment, but the air is cooling down.
- Harvest Window: These plants will form heads through the fall and winter, ready for harvest from late fall into early spring.
Late Winter / Early Spring Planting
This is your second chance, but it requires more precise timing. You need to get plants in the ground early enough to mature before the summer heat arrives.
- Start Seeds Indoors: Sow seeds in late December or early January.
- Transplant Outdoors: Harden off and transplant seedlings in late January or February, as soon as the soil is workable.
- The Goal: These cabbages will mature in the cool of early to mid-spring, allowing for a harvest before the heat of May or June causes them to bolt (flower prematurely).
Why Summer Planting Fails
Planting cabbage in spring for a summer harvest is a common mistake in zone 9. High temperatures cause several problems:
- Bolting: The plant rushes to produce flowers and seeds, ruining the head.
- Poor Head Formation: Heads may be loose, small, or fail to form at all.
- Increased Pests: Warm weather brings more insects like cabbage loopers and aphids.
Step-by-Step Planting Guide
Once you’ve got your timing down, follow these steps for healthy plants.
1. Choosing the Right Variety
Select varieties known for heat-tolerance and suited to your season. Some reliable choices for zone 9 include:
- ‘Early Jersey Wakefield’ (pointed head, good for spring)
- ‘Charleston Wakefield’ (similar but larger)
- ‘Golden Acre’ (early, compact)
- ‘Savoy King’ (crinkled, sweet leaves)
- ‘Red Acre’ (beautiful purple-red heads)
2. Starting Seeds vs. Buying Transplants
You can do either, but starting seeds gives you more variety control.
- For Seed Starting: Use a seed-starting mix. Plant seeds ¼ inch deep. Keep moist and warm (70°F) until germination, then provide plenty of light.
- For Transplants: Choose stocky, healthy plants without any yellowing leaves or signs of pests. Avoid plants that already look root-bound.
3. Preparing Your Garden Bed
Cabbage are heavy feeders and need nutrient-rich, well-draining soil.
- Work in 2-3 inches of compost or well-rotted manure.
- Mix in a balanced, slow-release organic fertilizer according to package directions.
- Ensure the bed gets full sun (at least 6 hours).
4. Transplanting Seedlings
- Harden off home-started seedlings for 7-10 days before transplanting.
- Space plants 12-18 inches apart in rows 2-3 feet apart. Dwarf varieties can be closer.
- Plant them at the same depth they were growing in their container.
- Water thoroughly immediately after planting to settle the soil.
Essential Care Tips for Zone 9 Cabbage
Consistent care is crucial, especially in your unique climate.
Watering
Cabbage needs consistent moisture for steady growth and to prevent heads from splitting.
- Provide 1-1.5 inches of water per week, more during dry spells.
- Water at the base of the plant to keep leaves dry and prevent disease.
- Using a soaker hose or drip irrigation is highly recommended.
Fertilizing
Feed your plants to support there large leaf and head growth.
- Side-dress with a nitrogen-rich fertilizer (like fish emulsion or blood meal) 3 weeks after transplanting and again when heads begin to form.
- Don’t over-fertilize late in the season, as this can harm head development.
Pest and Disease Management
Stay vigilant. Common issues include:
- Cabbage Worms/Loopers: Handpick or use Bacillus thuringiensis (Bt), a natural bacterial spray.
- Aphids: Blast them off with a strong stream of water or use insecticidal soap.
- Downy Mildew: Improve air circulation, water at the base, and rotate crops each year.
Floating row covers installed right after planting can exclude many pests from the start.
Harvesting Your Cabbage
Harvest when heads feel firm and solid when you gently squeeze them.
- Use a sharp knife to cut the head from the base of the plant.
- You can leave the outer leaves and roots in the ground; sometimes you’ll get a few small secondary heads.
- For your fall crop, a light frost can actually improve the flavor, making it sweeter.
Frequently Asked Questions (FAQ)
Can you grow cabbage in zone 9 year-round?
Not quite. The summer heat is too intense. You can, however, have cabbage in the garden for much of the year by using the fall and late winter planting windows.
What is the best month to plant cabbage in zone 9?
For a fall crop, transplant in September. For a spring crop, transplant in late January or February. The exact best month can vary slightly depending on if you’re in a coastal or inland part of zone 9.
How late can you plant cabbage in zone 9?
For a fall crop, you can risk transplanting as late as early October, but the heads may be smaller if winter cool arrives early. For spring, planting after mid-March is usually too late, as plants won’t mature before it gets hot.
Should I start cabbage seeds indoors for zone 9?
Yes, starting seeds indoors is highly recommended. It gives you a wider choice of varieties and allows you to control the seedlings early environment, ensuring they are strong for transplanting at the perfect time.
Why are my cabbage plants bolting?
Bolting is caused by stress, most often from temperatures that are too warm. If you planted too late in spring or an unexpected heatwave hits, the plant thinks its season is ending and goes to seed. Sticking to the optimal planting times is the best prevention.