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When to Plant Cilantro in St. Lawrence County, NY

St. Lawrence County, New York Zone 4b May

This month in St. Lawrence County, New York

May is a pivotal month for St. Lawrence County, New York gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost May 10
Avg. first frost October 2
Soil temp (4") 55°F
Watering Low
Pest pressure Low
Daylight 14.6 hrs
  1. Get cilantro in the ground

    Harden off for 7 days — a little more sun each day — before planting. That's the difference between a seedling that thrives and one that stalls.

  2. Seed cilantro outdoors

    Keep the top inch of soil moist until germination — a gentle morning watering for 5–7 days does the job.

To set up a strong June, finish these tasks
  • Starting indoors: cilantro
  • First harvests: cilantro

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Cilantro is a dual-purpose herb providing fresh leaves (cilantro) and dried seeds (coriander). It bolts quickly in heat, producing flowers beloved by beneficial insects.

St. Lawrence County, New York is in USDA Zone 4b. The average last spring frost is May 10 and the first fall frost is October 2, giving you a growing season of approximately 145 days.

At an elevation of 688 feet, St. Lawrence County receives approximately 39.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Cilantro to ensure they mature before fall.

St. Lawrence County, NY (Zone 4b) Short season
145 days
Last Spring Frost May 10
145 growing days
First Fall Frost October 2
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St. Lawrence County Soil Profile

Soil Type

Silt Loam

Soil pH

4.9-6.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (52 days to spare)
Start indoors: Mar 20 Transplant: Apr 24 🍅 Harvest: Jun 5 – Aug 7
Recommended (50%) ✓ Fits season (47 days to spare)
Start indoors: Mar 29 Transplant: May 3 🍅 Harvest: Jun 14 – Aug 16
Safe Start (90%) ✓ Fits season (47 days to spare)
Start indoors: Apr 14 Transplant: May 19 🍅 Harvest: Jun 30 – Sep 1

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 St. Lawrence County

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

Soil pH

Your soil pH (4.9–6.6) is more acidic than Cilantro prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

The silt loam soil in St. Lawrence County is excellent for Cilantro — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (3.9%). Annual compost additions will help Cilantro.

How to Plant Cilantro

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

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Succession Planting Cilantro

4
successive plantings in your 145-day season

Sow every 4.6 weeks. Last sowing by Aug 03 to harvest before frost.

For a dedicated fall crop, sow by Jul 10.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
1.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

Monthly Watering Guide for Cilantro

Cilantro needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.

Month Cilantro Needs Rainfall You Supplement Action
Jan 2.7" 0" ❄️ Dormant
Feb 2.6" 0" ❄️ Dormant
Mar 3.4" 0" ❄️ Dormant
Apr 3.1" 0" ❄️ Dormant
May 2.2" 3.8" 0" ✅ Rainfall sufficient
Jun 2.2" 3.6" 0" ✅ Rainfall sufficient
Jul 2.2" 4.4" 0" ✅ Rainfall sufficient
Aug 2.2" 3.3" 0" ✅ Rainfall sufficient
Sep 2.2" 3.2" 0" ✅ Rainfall sufficient
Oct 2.2" 2.9" 0" ✅ Rainfall sufficient
Nov 2.9" 0" ❄️ Dormant
Dec 3.1" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in St. Lawrence County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Cilantro 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.

Cilantro needs ~650 GDD — county provides 1,885 GDD Excellent fit

Cilantro Planting Timeline — St. Lawrence County, NY

Cilantro Planting Calendar

Activity When Date Range
Start Indoors March 29 Mar 29 – Apr 12
Transplant Outdoors May 3 May 3 – May 17
Direct Sow May 3 May 3 – May 24
Harvest June 14 Jun 14 – Aug 16
Fall Sowing July 10 Jul 10 – Jul 24

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

Month-by-Month Timeline

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

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

40–60 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 4b

📆 Growing Season

145 days in St. Lawrence County

Growing Tips for Cilantro in St. Lawrence County

Direct sow Cilantro outdoors after May 10 in St. Lawrence County when soil has warmed and frost danger has passed.

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

General growing tips

Succession sow every 2-3 weeks. Provide afternoon shade in warm weather. Harvest leaves before flowering or allow some plants to go to seed for coriander and self-sowing.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Cilantro in St. Lawrence County, NY?

St. Lawrence County is in Zone 4b with an average last frost of May 10. Plan your Cilantro planting based on this frost date — see the calendar above for exact timing.

What planting zone is St. Lawrence County, NY?

St. Lawrence County, New York is in USDA Hardiness Zone 4b. The average last spring frost is May 10 and first fall frost is October 2.

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Your St. Lawrence County Garden Planner — Free

A 24-page printable planner built for St. Lawrence County (Zone 4b). 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 St. Lawrence County, NY. 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.