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When to plant Leeks in Trimble, MO

Trimble's climate puts the Leeks spring window between March 30 and April 20. time plantings around the expected last-frost window for best survival. A second sowing from August 16 to August 30 extends the harvest into fall.

When to Plant Leeks in Trimble, MO

Leeks
Clinton County, Missouri Zone 6a August

Your August gardening checklist

August is a pivotal month for Clinton County, Missouri gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost April 13
Avg. first frost October 25
Soil temp (4") 77°F
Watering Moderate
Pest pressure High
Daylight 13.6 hrs
  1. Harvest leeks as they ripen

    The more you pick, the more the plant produces. Letting fruit overripen tells the plant it's time to stop.

  2. Direct-sow leeks for cool weather

    A row cover ready in the garage extends your harvest by weeks once the nights turn cold.

Looking ahead to September
  • 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.

Trimble, Missouri is in USDA Zone 6a. The average last spring frost is April 13 and the first fall frost is October 25, giving you a growing season of approximately 195 days.

At an elevation of 525 feet, Clinton County receives approximately 36.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Leeks to ensure they mature before fall.

Trimble, MO (Zone 6a) Moderate season
195 days
Last Spring Frost April 13
195 growing days
First Fall Frost October 25

Trimble Soil Profile

Soil Type

Silt Loam

Soil pH

5.5-7.1

Drainage

Well Drained

Leeks Planting Risk Windows

Early Start (70% safe) ✓ Fits season (28 days to spare)
Start indoors: Feb 28 Transplant: Apr 4 🍅 Harvest: Jul 4 – Sep 19
Recommended (50%) ✓ Fits season (27 days to spare)
Start indoors: Mar 9 Transplant: Apr 13 🍅 Harvest: Jul 13 – Sep 28
Safe Start (90%) ✓ Fits season (29 days to spare)
Start indoors: Mar 22 Transplant: Apr 26 🍅 Harvest: Jul 26 – Oct 11

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 Trimble

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

Soil pH

Your soil pH (5.5–7.1) overlaps with Leeks's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.6%). 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.

Leeks Water Budget

Plant needs
0.8″/week
Rainfall provides
0.8″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 17 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 1.6" 0" ❄️ Dormant
Feb 1.6" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 3.5" 3.2" 0.3" 💧 Light watering
May 3.5" 4.9" 0" ✅ Rainfall sufficient
Jun 3.5" 4.5" 0" ✅ Rainfall sufficient
Jul 3.5" 3.9" 0" ✅ Rainfall sufficient
Aug 3.5" 3.4" 0.1" 💧 Light watering
Sep 3.5" 3.6" 0" ✅ Rainfall sufficient
Oct 3.5" 3.3" 0.2" 💧 Light watering
Nov 2.4" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Clinton 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 ~1,470 GDD — county provides 2,388 GDD Excellent fit

Leeks Planting Timeline — Trimble, MO

Leeks Planting Calendar

Activity When Date Range
Start Indoors March 9 Mar 9 – Mar 23
Transplant Outdoors April 13 Apr 13 – Apr 27
Direct Sow March 30 Mar 30 – Apr 20
Harvest July 13 Jul 13 – Sep 28
Fall Sowing August 16 Aug 16 – Aug 30

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.8"/week · Only during dry spells

📅 Days to Maturity

90–150 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 6a

📆 Growing Season

195 days in Clinton County

Growing Tips for Leeks in Trimble

Direct sow Leeks outdoors after April 13 in Clinton 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 →

When should I plant Leeks in Trimble, MO?

In Trimble, MO, plant Leeks after the last frost (around April 13) and before the first frost (around October 25). Best results when soil holds above 50°F.

What growing zone is Trimble, MO for Leeks?

Trimble sits in USDA Zone 6a. Leeks grows reliably in zones 3a through 10b, so it's a good fit here.

Can Leeks grow in Trimble's climate?

Yes — Leeks grows well in Trimble's temperate climate. Trimble averages a 195-day frost-free season, with last frost around April 13 and first frost around October 25.

🌱

Your Clinton County Garden Planner — Free

A 22-page printable planner built for Clinton County (Zone 6a). 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 Clinton County, MO. Local conditions may vary. Last updated: August 2026.