Blog

When to Plant Leeks in Wibaux County, MT

Wibaux County, Montana Zone 4a May

Wibaux County, Montana gardeners: here's your May plan

Welcome to May in Zone 4a. These are the moves that will have the biggest impact on your growing season.

Avg. last frost May 14
Avg. first frost September 22
Soil temp (4") 31°F
Watering High
Pest pressure Low
Daylight 14.8 hrs
  1. Set out leeks seedlings

    Pick a cloudy afternoon or evening to plant. Less transplant shock, and your seedlings will barely blink.

  2. Outdoor sowing time: leeks

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

Looking ahead to June
  • Starting indoors: leeks
  • Fall sowing: leeks

Instant PDF download. No spam, unsubscribe any time.

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.

Wibaux County, Montana is in USDA Zone 4a. The average last spring frost is May 14 and the first fall frost is September 22, giving you a growing season of approximately 131 days.

At an elevation of 7,076 feet, Wibaux County receives approximately 15.4 inches of rainfall annually with predominantly loam soil. Summer highs average 82°F, so choose short-season varieties of Leeks to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Leeks successfully. Mulch heavily to conserve soil moisture.

Wibaux County, MT (Zone 4a) Short season
131 days
Last Spring Frost May 14
131 growing days
First Fall Frost September 22
Share this guide:

Wibaux County Soil Profile

Soil Type

Loam

Soil pH

6.5-8.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 29 Transplant: May 10 🍅 Harvest: Aug 9 – Oct 4
Recommended (50%) ✗ May not fit
Start indoors: Apr 2 Transplant: May 14 🍅 Harvest: Aug 13 – Oct 8
Safe Start (90%) ✗ May not fit
Start indoors: Apr 15 Transplant: May 27 🍅 Harvest: Aug 26 – Oct 21

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 Wibaux County

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

Soil pH

Your soil pH (6.5–8.3) is more alkaline than Leeks prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.3%). Annual compost additions will help Leeks.

How to Plant Leeks

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

Fall planting: Sow 12 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 428 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 1.1" 0" ❄️ Dormant
Feb 1" 0" ❄️ Dormant
Mar 1.2" 0" ❄️ Dormant
Apr 1.7" 0" ❄️ Dormant
May 3.5" 1.6" 1.9" 🚿 Regular watering
Jun 3.5" 1.1" 2.4" 🚿 Regular watering
Jul 3.5" 1.6" 1.9" 🚿 Regular watering
Aug 3.5" 1.4" 2.1" 🚿 Regular watering
Sep 3.5" 1.3" 2.2" 🚿 Regular watering
Oct 1.3" 0" ❄️ Dormant
Nov 1.1" 0" ❄️ Dormant
Dec 1" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Wibaux 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 ~1,380 GDD — county provides 1,506 GDD Good fit

Leeks Planting Timeline — Wibaux County, MT

Leeks Planting Calendar

Activity When Date Range
Start Indoors April 2 Apr 2 – Apr 16
Transplant Outdoors May 14 May 14 – May 28
Direct Sow May 7 May 7 – May 28
Harvest August 13 Aug 13 – Oct 8
Fall Sowing June 30 Jun 30 – Jul 14

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

Month-by-Month Timeline

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

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 4a

📆 Growing Season

131 days in Wibaux County

Growing Tips for Leeks in Wibaux County

Direct sow Leeks outdoors after May 14 in Wibaux County when soil has warmed and frost danger has passed.

Your 131.0-day growing season in Wibaux County is tight for Leeks (90.0-150.0 days to maturity). Start indoors and choose early-maturing varieties.

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 Wibaux County, MT?

Wibaux County is in Zone 4a with an average last frost of May 14. Plan your Leeks planting based on this frost date — see the calendar above for exact timing.

What planting zone is Wibaux County, MT?

Wibaux County, Montana is in USDA Hardiness Zone 4a. The average last spring frost is May 14 and first fall frost is September 22.

🌱

Your Wibaux County Garden Planner — Free

A 24-page printable planner built for Wibaux County (Zone 4a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Wibaux County, MT. 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.