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When to Plant Collard Greens in St. Lawrence County, NY

St. Lawrence County, New York Zone 4b May

Your May planting checklist for St. Lawrence County, New York

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in St. Lawrence County, New York.

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. Plant out collard greens

    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. Plant collard greens from seed, right in the garden

    Thin ruthlessly once seedlings are up. Crowded roots mean smaller crops from every plant.

Coming up in June — start thinking about
  • Starting indoors: collard greens

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Collard greens are a heat-tolerant member of the cabbage family with large, sturdy leaves. They are a Southern staple and one of the most nutritious leafy greens.

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 Collard Greens 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 (31 days to spare)
Start indoors: Mar 20 Transplant: May 1 🍅 Harvest: Jun 26 – Aug 28
Recommended (50%) ✓ Fits season (26 days to spare)
Start indoors: Mar 29 Transplant: May 10 🍅 Harvest: Jul 5 – Sep 6
Safe Start (90%) ✓ Fits season (26 days to spare)
Start indoors: Apr 14 Transplant: May 26 🍅 Harvest: Jul 21 – Sep 22

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 Collard Greens's growing requirements.

Soil pH

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

Soil Texture

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

Organic Matter

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

How to Plant Collard Greens

1"
Planting Depth
15"
Between Plants
24"
Between Rows

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

Succession Planting Collard Greens

3
successive plantings in your 145-day season

Sow every 6.3 weeks. Last sowing by Jul 19 to harvest before frost.

For a dedicated fall crop, sow by Jul 10.

Plant Water Budget

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

Monthly Watering Guide for Collard Greens

Collard Greens 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 Collard Greens 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 3.5" 3.8" 0" ✅ Rainfall sufficient
Jun 3.5" 3.6" 0" ✅ Rainfall sufficient
Jul 3.5" 4.4" 0" ✅ Rainfall sufficient
Aug 3.5" 3.3" 0.2" 💧 Light watering
Sep 3.5" 3.2" 0.3" 💧 Light watering
Oct 3.5" 2.9" 0.6" 💧 Light watering
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.

Collard Greens 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.

Collard Greens needs ~845 GDD — county provides 1,885 GDD Excellent fit

Collard Greens Planting Timeline — St. Lawrence County, NY

Collard Greens Planting Calendar

Activity When Date Range
Start Indoors March 29 Mar 29 – Apr 12
Transplant Outdoors May 10 May 10 – May 24
Direct Sow May 3 May 3 – May 24
Harvest July 5 Jul 5 – Sep 6
Fall Sowing July 10 Jul 10 – Jul 24

Plant 1" deep · 15" apart · Rows 24" apart

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.8"/week · Natural rainfall sufficient

📅 Days to Maturity

55–75 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 Collard Greens in St. Lawrence County

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

Common pests for Collard Greens in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors or direct sow 4-6 weeks before last frost. Harvest lower leaves first, leaving the growing tip intact. Flavor improves after exposure to frost.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries
  • Tomatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

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

St. Lawrence County is in Zone 4b with an average last frost of May 10. Plan your Collard Greens 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.

🌱

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.