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When to plant Leeks in Powell County, MT

For Powell County, gardeners: plant Leeks May 30 through June 20 once soil reads 50°F. A second sowing from June 16 to June 30 extends the harvest into fall.

When to Plant Leeks in Powell County, MT

Leeks
Powell County, Montana Zone 4b June

Top priorities for Powell County, Montana gardeners in June

If you only do a handful of things in the garden this June, make it these. They're sequenced around your zone's frost timing.

Avg. last frost June 6
Avg. first frost September 8
Soil temp (4") 47°F
Watering High
Pest pressure High
Daylight 15.6 hrs
  1. Transplant leeks outside

    Frost risk is low now in Powell County, Montana. If you've been covering beds overnight, you can stop.

  2. Start your fall crops: leeks

    Count back from your first frost (September 8) — these need to mature before the cold arrives.

July prep starts now
  • Starting indoors: 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.

Powell County, Montana is in USDA Zone 4b. The average last spring frost is June 6 and the first fall frost is September 8, giving you a growing season of approximately 94 days.

At an elevation of 5,514 feet, Powell County receives approximately 22.9 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Leeks to ensure they mature before fall.

Powell County, MT (Zone 4b) Very short season
94 days
Last Spring Frost June 6
94 growing days
First Fall Frost September 8

Powell County Soil Profile

Soil Type

Loam

Soil pH

6.5-8.2

Drainage

Well Drained

Leeks Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 8 Transplant: May 20 🍅 Harvest: Aug 19 – Oct 14
Recommended (50%) ✗ May not fit
Start indoors: Apr 25 Transplant: Jun 6 🍅 Harvest: Sep 5 – Oct 31
Safe Start (90%) ✗ May not fit
Start indoors: May 9 Transplant: Jun 20 🍅 Harvest: Sep 19 – Nov 14

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 Powell County

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

Soil pH

Your soil pH (6.5–8.2) is more alkaline than Leeks prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.4%). 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.

Leeks Water Budget

Plant needs
0.8″/week
Rainfall provides
1.0″/week
Watering frequency Natural rainfall sufficient
Season total 0 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 1.6" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 2" 0" ❄️ Dormant
Apr 2.4" 0" ❄️ Dormant
May 3" 0" ❄️ Dormant
Jun 3.5" 1.4" 2.1" 🚿 Regular watering
Jul 3.5" 2.1" 1.4" 💧 Light watering
Aug 3.5" 2.2" 1.3" 💧 Light watering
Sep 3.5" 1.8" 1.7" 💧 Light watering
Oct 2.1" 0" ❄️ Dormant
Nov 1.7" 0" ❄️ Dormant
Dec 1.3" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Sep in Powell 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 ~1,560 GDD — county provides 1,222 GDD May not mature

Leeks Planting Timeline — Powell County, MT

Leeks Planting Calendar

Activity When Date Range
Start Indoors April 25 Apr 25 – May 9
Transplant Outdoors June 6 Jun 6 – Jun 20
Direct Sow May 30 May 30 – Jun 20
Harvest September 5 Sep 5 – Oct 31
Fall Sowing June 16 Jun 16 – Jun 30

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.8"/week · Natural rainfall sufficient

📅 Days to Maturity

90–150 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 4b

📆 Growing Season

94 days in Powell County

Growing Tips for Leeks in Powell County

Direct sow Leeks outdoors after June 06 in Powell County when soil has warmed and frost danger has passed.

Your 94.0-day growing season in Powell 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 Powell County, MT?

Powell County is in Zone 4b with an average last frost of June 6. Plan your Leeks planting based on this frost date — see the calendar above for exact timing.

What planting zone is Powell County, MT?

Powell County, Montana is in USDA Hardiness Zone 4b. The average last spring frost is June 6 and first fall frost is September 8.

When should I plant Leeks in Powell County, MT?

In Powell County, MT, plant Leeks after the last frost (around June 6) and before the first frost (around September 8). Best results when soil holds above 50°F.

What growing zone is Powell County, MT for Leeks?

Powell County sits in USDA Zone 4b. Leeks grows reliably in zones 3a through 10b, so it's a good fit here.

Can Leeks grow in Powell County's climate?

Yes — Leeks grows well in Powell County's temperate climate. Powell County averages a 94-day frost-free season, with last frost around June 6 and first frost around September 8.

🌱

Your Powell County Garden Planner — Free

A 22-page printable planner built for Powell 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.

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 Powell County, MT. Local conditions may vary. Last updated: June 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.