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When to Plant Leeks in Jefferson County, OK

Jefferson County, Oklahoma Zone 8a May

Your May planting checklist for Jefferson County, Oklahoma

We've pulled the most time-sensitive tasks for Jefferson County, Oklahoma this May and put them front and centre. Tackle them in order.

Avg. last frost March 26
Avg. first frost November 9
Soil temp (4") 67°F
Watering Moderate
Pest pressure Moderate
Daylight 13.8 hrs
Get ahead of June
  • 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.

Jefferson County, Oklahoma is in USDA Zone 8a. The average last spring frost is March 26 and the first fall frost is November 9, giving you a growing season of approximately 228 days.

At an elevation of 883 feet, Jefferson County receives approximately 24.7 inches of rainfall annually with predominantly loam soil. Summer highs average 91°F, providing good warmth for Leeks during the growing season.

Jefferson County, OK (Zone 8a) Long season
228 days
Last Spring Frost March 26
228 growing days
First Fall Frost November 9

Jefferson County Soil Profile

Soil Type

Loam

Soil pH

6.6-7.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (61 days to spare)
Start indoors: Feb 9 Transplant: Mar 16 🍅 Harvest: Jun 15 – Aug 31
Recommended (50%) ✓ Fits season (60 days to spare)
Start indoors: Feb 19 Transplant: Mar 26 🍅 Harvest: Jun 25 – Sep 10
Safe Start (90%) ✓ Fits season (55 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 Jefferson County

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

Soil pH

Your soil pH (6.6–7.5) is more alkaline than Leeks prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.1%) — Leeks will thrive.

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
0.5″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 700 gal / 100 sq ft

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" 1.7" 1.8" 🚿 Regular watering
Apr 3.5" 2.7" 0.8" 💧 Light watering
May 3.5" 3.2" 0.3" 💧 Light watering
Jun 3.5" 4" 0" ✅ Rainfall sufficient
Jul 3.5" 3.1" 0.4" 💧 Light watering
Aug 3.5" 3.2" 0.3" 💧 Light watering
Sep 3.5" 2.1" 1.4" 💧 Light watering
Oct 3.5" 1.6" 1.9" 🚿 Regular watering
Nov 3.5" 0.8" 2.7" 🚿 Regular watering
Dec 0.7" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Jefferson 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 ~2,190 GDD — county provides 4,161 GDD Excellent fit

Leeks Planting Timeline — Jefferson County, OK

Leeks Planting Calendar

Activity When Date Range
Start Indoors February 19 Feb 19 – Mar 5
Transplant Outdoors March 26 Mar 26 – Apr 9
Direct Sow March 12 Mar 12 – Apr 2
Harvest June 25 Jun 25 – Sep 10
Fall Sowing August 31 Aug 31 – Sep 14

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

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 8a

📆 Growing Season

228 days in Jefferson County

Growing Tips for Leeks in Jefferson County

Direct sow Leeks outdoors after March 26 in Jefferson 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 Jefferson County, OK?

Jefferson County is in Zone 8a with an average last frost of March 26. Plan your Leeks planting based on this frost date — see the calendar above for exact timing.

What planting zone is Jefferson County, OK?

Jefferson County, Oklahoma is in USDA Hardiness Zone 8a. The average last spring frost is March 26 and first fall frost is November 9.

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Your Jefferson County Garden Planner — Free

A 24-page printable planner built for Jefferson County (Zone 8a). 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 Jefferson 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.