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When to Plant Leeks in Seminole County, OK

Seminole County, Oklahoma Zone 7b May

Top priorities for Seminole County, Oklahoma gardeners in May

Here's what deserves your attention in Seminole County, Oklahoma this month. Everything below is tailored to Zone 7b and timed around your local frost dates.

Avg. last frost March 31
Avg. first frost November 6
Soil temp (4") 69°F
Watering Moderate
Pest pressure Moderate
Daylight 13.8 hrs
  1. Begin indoor sowing: leeks

    You're about 25 weeks out from your last frost — the perfect window to get these germinating indoors.

Before June arrives, get these ready
  • First harvests: leeks

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Leeks are a mild, sweet allium that produces long white shanks. They are more refined than onions and are a key ingredient in soups, stews, and gratins.

Seminole County, Oklahoma is in USDA Zone 7b. The average last spring frost is March 31 and the first fall frost is November 6, giving you a growing season of approximately 220 days.

At an elevation of 961 feet, Seminole County receives approximately 20.7 inches of rainfall annually with predominantly loam soil. Summer highs average 94°F, providing good warmth for Leeks during the growing season.

Seminole County, OK (Zone 7b) Long season
220 days
Last Spring Frost March 31
220 growing days
First Fall Frost November 6
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Seminole County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (50 days to spare)
Start indoors: Feb 17 Transplant: Mar 24 🍅 Harvest: Jun 23 – Sep 8
Recommended (50%) ✓ Fits season (52 days to spare)
Start indoors: Feb 24 Transplant: Mar 31 🍅 Harvest: Jun 30 – Sep 15
Safe Start (90%) ✓ Fits season (54 days to spare)
Start indoors: Mar 11 Transplant: Apr 15 🍅 Harvest: Jul 15 – Sep 30

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 Seminole County

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

Soil pH

Your soil pH (6.7–7.5) is more alkaline than Leeks prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Seminole County is excellent for Leeks — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

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

How to Plant Leeks

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

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Plant Water Budget

Plant needs
0.8″/week
Rainfall provides
0.4″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 951 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Leeks

Leeks 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 Leeks Needs Rainfall You Supplement Action
Jan 0.6" 0" ❄️ Dormant
Feb 0.8" 0" ❄️ Dormant
Mar 3.5" 1.4" 2.1" 🚿 Regular watering
Apr 3.5" 2.1" 1.4" 💧 Light watering
May 3.5" 3.2" 0.3" 💧 Light watering
Jun 3.5" 3.3" 0.2" 💧 Light watering
Jul 3.5" 2.4" 1.1" 💧 Light watering
Aug 3.5" 2.8" 0.7" 💧 Light watering
Sep 3.5" 1.7" 1.8" 🚿 Regular watering
Oct 3.5" 1.3" 2.2" 🚿 Regular watering
Nov 3.5" 0.8" 2.7" 🚿 Regular watering
Dec 0.5" 0" ❄️ Dormant

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

Leeks 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.

Leeks needs ~2,460 GDD — county provides 4,510 GDD Excellent fit

Leeks Planting Timeline — Seminole County, OK

Leeks Planting Calendar

Activity When Date Range
Start Indoors February 24 Feb 24 – Mar 10
Transplant Outdoors March 31 Mar 31 – Apr 14
Direct Sow March 17 Mar 17 – Apr 7
Harvest June 30 Jun 30 – Sep 15
Fall Sowing August 28 Aug 28 – Sep 11

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.8"/week · 1-2 times/week

📅 Days to Maturity

90–150 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 7b

📆 Growing Season

220 days in Seminole County

Growing Tips for Leeks in Seminole County

Direct sow Leeks outdoors after March 31 in Seminole County when soil has warmed and frost danger has passed.

Common pests for Leeks in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors 10-12 weeks before last frost. Transplant into trenches and hill soil around stems as they grow to increase the white portion. Harvest as needed.

Companion Planting

Good Companions

Avoid Planting Near

  • Peas
  • Green Beans

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Leeks in Seminole County, OK?

Seminole County is in Zone 7b with an average last frost of March 31. Plan your Leeks planting based on this frost date — see the calendar above for exact timing.

What planting zone is Seminole County, OK?

Seminole County, Oklahoma is in USDA Hardiness Zone 7b. The average last spring frost is March 31 and first fall frost is November 6.

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Your Seminole County Garden Planner — Free

A 24-page printable planner built for Seminole County (Zone 7b). 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 Seminole County, OK. 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.