What to plant in December — zone 9b
Zone 9b averages its last spring frost around February 15 and its first fall frost around December 15. Everything below is timed from those two dates, so it stays useful whether you're planting for summer or for a fall harvest.
Start indoors
- Start onions and leeks indoorsaround Dec 7
Alliums need 10-12 weeks under lights before they go out — the earliest sowing of the year.
- Onionaround Dec 7
10 weeks of indoor growth before your last frost (02-15). Match day-length to your latitude — long-day north of 37°, short-day south.
- Rosemaryaround Dec 7
10 weeks of indoor growth before your last frost (02-15). In zone 6 and below, grow in a pot and overwinter indoors near a south window.
- Pepperaround Dec 21
8 weeks of indoor growth before your last frost (02-15). Pinch first flowers on transplants so the plant invests in roots before setting fruit.
- Parsleyaround Dec 21
8 weeks of indoor growth before your last frost (02-15). Soak seeds 24 hrs before sowing. Cut outer stems and it comes back for years in mild zones.
- Chivesaround Dec 21
8 weeks of indoor growth before your last frost (02-15). Divide the clump every 3 years — one plant becomes six with no effort.
- Oreganoaround Dec 21
8 weeks of indoor growth before your last frost (02-15). Harvest just before flowering for the strongest flavor. Dries beautifully.
- Thymearound Dec 21
8 weeks of indoor growth before your last frost (02-15). Needs sharp drainage — plant in gravelly soil or a raised bed edge. Never wet feet.
- Sagearound Dec 21
8 weeks of indoor growth before your last frost (02-15). Prune hard in spring to prevent woody stems and keep the plant productive for 5+ years.
Dormant care
- Check season-extension geararound Dec 21
Patch row cover, cold frames and hoops now so a late freeze can't catch you unprepared.
Plant to overwinter
- Garlicaround Dec 1
Cloves go in about two weeks before first frost — they root now, sleep, then bulb next summer.
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