When to Plant Carrots in Marin County, CA
Top priorities for Marin County, California gardeners in May
May is a pivotal month for Marin County, California gardens. Focus on these tasks first and you'll set up the rest of the season for success.
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Basket week: carrots
Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.
Carrots are a popular root vegetable available in orange, purple, white, and yellow varieties. They are rich in beta-carotene and have a sweet, earthy flavor.
Marin County, California is in USDA Zone 9b. The average last spring frost is February 26 and the first fall frost is November 26, giving you a growing season of approximately 273 days.
At an elevation of 302 feet, Marin County receives approximately 36 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 81°F, so choose short-season varieties of Carrots to ensure they mature before fall. Sandy soil warms quickly in spring — great for early planting — but Carrots will need more frequent watering and organic matter to retain nutrients.
Marin County Soil Profile
Soil Type
Sandy Loam
Soil pH
6-6.9
Drainage
Well Drained
Plant Planting Risk Windows
Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.
Soil Compatibility in Marin County
How your county's soil matches Carrots's growing requirements.
Soil pH
Your soil pH (6.0–6.9) overlaps with Carrots's range (6.0–6.8), though not a perfect match.
Soil Texture
Sandy soil in Marin County warms quickly in spring but drains fast. Carrots will need more frequent watering and regular compost additions to retain nutrients.
Organic Matter
Organic matter is moderate (2.3%). Annual compost additions will help Carrots.
How to Plant Carrots
Fall planting: Sow 8 weeks before your first frost date for a fall harvest.
Succession Planting Carrots
Sow every 6.9 weeks. Last sowing by Sep 07 to harvest before frost.
For a dedicated fall crop, sow by Oct 01.
Plant Water Budget
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Carrots
Carrots needs approximately 0.8 inches of water per week (3.5" per month). Here's how your county's rainfall compares month by month.
| Month | Carrots Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 7.2" | 0" | ❄️ Dormant |
| Feb | 3.5" | 6.5" | 0" | ✅ Rainfall sufficient |
| Mar | 3.5" | 6.2" | 0" | ✅ Rainfall sufficient |
| Apr | 3.5" | 2.7" | 0.8" | 💧 Light watering |
| May | 3.5" | 1" | 2.5" | 🚿 Regular watering |
| Jun | 3.5" | 0.2" | 3.3" | 🚿 Regular watering |
| Jul | 3.5" | 0" | 3.5" | 🚿 Regular watering |
| Aug | 3.5" | 0" | 3.5" | 🚿 Regular watering |
| Sep | 3.5" | 0.4" | 3.1" | 🚿 Regular watering |
| Oct | 3.5" | 1.4" | 2.1" | 🚿 Regular watering |
| Nov | 3.5" | 3.5" | 0" | ✅ Rainfall sufficient |
| Dec | — | 6.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Feb–Nov in Marin County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Carrots Heat Requirements (GDD)
What are Growing Degree Days (GDD)?
Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.
Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.
Carrots Planting Timeline — Marin County, CA
Carrots Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | February 5 | Feb 5 – Feb 26 |
| Harvest | April 9 | Apr 9 – May 14 |
| Fall Sowing | October 1 | Oct 1 – Oct 15 |
Plant 0.5" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Direct Sow |
| March | — |
| April | Harvest |
| May | Harvest |
| June | — |
| July | — |
| August | — |
| September | — |
| October | Fall Sowing |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.8"/week · Only during dry spells
📅 Days to Maturity
60–80 days
🧪 Soil pH
Needs 6–6.8 · Your soil: acceptable
🗺️ USDA Zone
Zone 9b
📆 Growing Season
273 days in Marin County
Growing Tips for Carrots in Marin County
Direct sow Carrots outdoors after February 26 in Marin County when soil has warmed and frost danger has passed.
Sandy soil in Marin County dries quickly — mulch Carrots with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.
Common pests for Carrots in this region include carrot rust fly and parsleyworm. Use row covers early in the season and inspect plants weekly.
General growing tips
Sow seeds directly in loose, stone-free soil for straight roots. Keep soil moist until germination which can take 2-3 weeks. Thin seedlings to 2 inches apart.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Isolate 1/2 mile from Queen Anne's Lace (wild carrot). Biennial — requires two seasons.
Carrots in Other Locations
Frequently Asked Questions
When should I plant Carrots in Marin County, CA?
Marin County is in Zone 9b with an average last frost of February 26. Plan your Carrots planting based on this frost date — see the calendar above for exact timing.
What planting zone is Marin County, CA?
Marin County, California is in USDA Hardiness Zone 9b. The average last spring frost is February 26 and first fall frost is November 26.
Your Marin County Garden Planner — Free
A 24-page printable planner built for Marin County (Zone 9b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.