When to Plant Collard Greens in Concord, CA
Published: April 24, 2026
Collard Green Planting Dates for Concord, CA
| Start seeds indoors | December 11–18 |
| Last frost (average) | January 15 |
| Transplant outdoors | December 25–January 4 |
| Direct sow outdoors | December 25–January 4 |
| Minimum soil temperature | 45°F |
| Expect first harvest | February 23 – March 10 |
| Fall crop planting | October 22–November 1 |
| Fall crop harvest | December 21 |
| First fall frost (average) | December 31 |
⚠ Direct sow or transplant collard greens 3–4 weeks before last frost. Extremely cold hardy — withstands temps to 15°F. Can be grown as a perennial in Zones 8+. Fall planting produces the best-flavored greens.
Best Collard Green Varieties for Concord, CA
Consult a Concord-area nursery or your state extension office for collard green varieties proven in Zone 9b.
Growing Collard Greens in Concord
Concord sits in Zone 9b, with an average last frost of January 15 and first fall frost around December 31 — giving a 350-day frost-free growing season. Cool-season crops like collard green benefit from Concord's cooler spring and fall windows, when temperatures stay in the 55–75°F sweet spot that produces the best flavor and least bolting.
In Concord's warm climate, collard green works best as a fall, winter, and early-spring crop. Summer heat bolts most cool-season vegetables before they can produce a harvestable head or root. Plan primary plantings in October through February in Concord, not April through June.
Concord's mixed soil conditions vary block by block — get a soil test if you have not in three years. Generally, a base of quality compost (2 to 3 inches annually) and consistent watering at 1 inches per week serves collard green well across most soil types found in Concord.
Collard Green Calendar for Concord
| Month | Task |
|---|---|
| December | Start seeds indoors under grow lights |
| January | Last frost — harden off seedlings outdoors |
| December | Transplant outdoors into warm soil |
| February | Expect first harvest window to open |
| October | Start fall crop — transplants or direct sow |
| December | First fall frost — harvest remaining, end of outdoor season |
Collard Green Tips for Concord Gardeners
- •Harvest outer leaves continuously once plants reach 10 inches — the central growing point produces for months.
- •In Zones 8+ collard greens often overwinter and produce for 2–3 years as a perennial.
- •Plant cool-season collard green in Concord during October through February — spring plantings bolt before producing a usable crop in warm zones.
Common Collard Green Pests in Concord
- •Cabbage Worm — peaks June–August in Zone 9b (active March–October); green caterpillars on brassicas; apply Bt spray or use row covers.
- •Aphid — peaks June–August in Zone 9b (active March–October); monitor closely during peak season and treat early.
- •Flea Beetle — peaks June–August in Zone 9b (active March–October); tiny black beetles that riddle leaves with holes; row covers protect seedlings.
Check plants every 2–3 days during peak season — early intervention prevents most infestations from becoming serious.
What to Plant with Collard Greens in Concord
In Concord's warm climate, Onion and Garlic are the most beneficial plants to grow alongside collard green. Onion deters carrot fly, aphids, and several root-zone pests through sulfur compounds. Keep collard green away from Tomato — it competes for nutrients or shares pest pressure. Warm-climate gardeners especially benefit from dense, layered companion plantings that shade soil and reduce water loss.
Frequently Asked Questions
When should I plant collard green in Concord, CA?
In Concord (Zone 9b), start collard green seeds indoors around December 11–18 and transplant outdoors around December 25–January 4. The city's average last frost of January 15 is the anchor date — count 5 weeks back for seed starting and 3 weeks back for transplanting.
What zone is Concord, CA for collard green growing?
Concord is USDA Zone 9b. For collard green, this means a frost-free growing season of roughly 50 weeks running from January 15 to December 31. Cool-season crops like collard green thrive in this zone with both spring and fall planting windows available.
When is collard green harvest season in Concord?
Expect the first collard green harvest in Concord around February 23, with harvest continuing through March 10. This is based on 60–75 days from transplant or direct sow. A fall crop planted October 22–November 1 adds a second harvest around December 21.
How long does it take to grow collard green in Concord, CA?
From transplant or direct sow to first harvest, collard green takes 60–75 days in Concord's climate. Based on a typical planting date of December 25–January 4, expect your first harvest around February 23. Concord's warm Zone 9b climate tends toward the faster end of this range — warmer soil and longer days accelerate maturity.
What soil does collard green need in Concord?
Concord's soil conditions vary block by block. Before planting collard green, do a soil test (most state extension offices run them for $15–30). The test reveals pH, key nutrient levels, and organic matter content, so you can amend appropriately rather than guessing. Generally, 2–3 inches of compost annually improves most soils for vegetable production.