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When to Plant Parsley in San Luis Obispo County, CA

San Luis Obispo County, California Zone 10a May

May in San Luis Obispo County, California — your action list

Your garden in San Luis Obispo County, California is working on a schedule, even when you're not. Here's where you should be this May.

Avg. last frost March 23
Avg. first frost November 9
Soil temp (4") 71°F
Watering Critical
Pest pressure High
Daylight 13.9 hrs
  1. Collect parsley at their peak

    If you can't use it all right away, check the food-preservation section of your planner.

Looking ahead to June
  • First harvests: parsley

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Parsley is a biennial herb available in flat-leaf (Italian) and curly varieties. It is a nutritional powerhouse rich in vitamins C and K and adds fresh flavor to countless dishes.

San Luis Obispo County, California is in USDA Zone 10a. The average last spring frost is March 23 and the first fall frost is November 9, giving you a growing season of approximately 231 days.

At an elevation of 2,412 feet, San Luis Obispo County receives approximately 18.4 inches of rainfall annually with predominantly loam soil. Summer highs average 98°F, so Parsley may need afternoon shade and extra watering during peak heat. With low rainfall, drip irrigation is essential for growing Parsley successfully. Mulch heavily to conserve soil moisture.

San Luis Obispo County, CA (Zone 10a) Long season
231 days
Last Spring Frost March 23
231 growing days
First Fall Frost November 9
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San Luis Obispo County Soil Profile

Soil Type

Loam

Soil pH

6.6-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (122 days to spare)
Start indoors: Feb 5 Transplant: Feb 26 🍅 Harvest: Apr 30 – Jul 2
Recommended (50%) ✓ Fits season (112 days to spare)
Start indoors: Feb 23 Transplant: Mar 16 🍅 Harvest: May 18 – Jul 20
Safe Start (90%) ✓ Fits season (110 days to spare)
Start indoors: Mar 19 Transplant: Apr 9 🍅 Harvest: Jun 11 – Aug 13

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 San Luis Obispo County

How your county's soil matches Parsley's growing requirements.

Soil pH

Your soil pH (6.6–7.8) is more alkaline than Parsley prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in San Luis Obispo County is excellent for Parsley — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.9%). Annual compost additions will help Parsley.

How to Plant Parsley

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

Fall planting: Sow 8 weeks before your first frost date for a fall harvest.

Succession Planting Parsley

4
successive plantings in your 231-day season

Sow every 6.9 weeks. Last sowing by Aug 21 to harvest before frost.

For a dedicated fall crop, sow by Sep 14.

Plant Water Budget

Plant needs
0.6″/week
Rainfall provides
0.3″/week
You supply
0.3″/week
Watering frequency 1-2 times/week
Season total 655 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Parsley

Parsley needs approximately 0.6 inches of water per week (2.6" per month). Here's how your county's rainfall compares month by month.

Month Parsley Needs Rainfall You Supplement Action
Jan 4" 0" ❄️ Dormant
Feb 3.9" 0" ❄️ Dormant
Mar 2.6" 2.8" 0" ✅ Rainfall sufficient
Apr 2.6" 1.6" 1" 💧 Light watering
May 2.6" 0.5" 2.1" 🚿 Regular watering
Jun 2.6" 0.1" 2.5" 🚿 Regular watering
Jul 2.6" 0" 2.6" 🚿 Regular watering
Aug 2.6" 0" 2.6" 🚿 Regular watering
Sep 2.6" 0.2" 2.4" 🚿 Regular watering
Oct 2.6" 0.8" 1.8" 🚿 Regular watering
Nov 2.6" 1.8" 0.8" 💧 Light watering
Dec 2.8" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in San Luis Obispo County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Parsley 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.

Parsley needs ~1,645 GDD — county provides 5,428 GDD Excellent fit

Parsley Planting Timeline — San Luis Obispo County, CA

Parsley Planting Calendar

Activity When Date Range
Start Indoors February 23 Feb 23 – Mar 9
Transplant Outdoors March 16 Mar 16 – Mar 30
Direct Sow March 2 Mar 2 – Mar 23
Harvest May 18 May 18 – Jul 20
Fall Sowing September 14 Sep 14 – Sep 28

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February Start Indoors
March Start Indoors Transplant Outdoors Direct Sow
April
May Harvest
June Harvest
July Harvest
August
September Fall Sowing
October
November
December
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Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.6"/week · 1-2 times/week

📅 Days to Maturity

60–80 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 10a

📆 Growing Season

231 days in San Luis Obispo County

Growing Tips for Parsley in San Luis Obispo County

Direct sow Parsley outdoors after March 23 in San Luis Obispo County when soil has warmed and frost danger has passed.

With summer highs reaching 98°F in San Luis Obispo County, provide afternoon shade for Parsley and water deeply in the morning.

Common pests for Parsley in this region include carrot rust fly and parsleyworm. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors 6-8 weeks before last frost. Soak seeds overnight as germination is slow. Harvest outer stems first to keep plants productive. Parsley attracts swallowtail butterflies.

Companion Planting

Good Companions

Avoid Planting Near

  • Mint
  • Lettuce

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Parsley in San Luis Obispo County, CA?

San Luis Obispo County is in Zone 10a with an average last frost of March 23. Plan your Parsley planting based on this frost date — see the calendar above for exact timing.

What planting zone is San Luis Obispo County, CA?

San Luis Obispo County, California is in USDA Hardiness Zone 10a. The average last spring frost is March 23 and first fall frost is November 9.

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Your San Luis Obispo County Garden Planner — Free

A 24-page printable planner built for San Luis Obispo County (Zone 10a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for San Luis Obispo County, CA. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.