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When to plant Arugula in Silver Bow County, MT

In Zone 5a (Silver Bow County), direct-sow Arugula between June 1 and June 22 for spring, after the June 15 last-frost mark. A second sowing from June 29 to July 13 extends the harvest into fall.

When to Plant Arugula in Silver Bow County, MT

Silver Bow County, Montana Zone 5a June

June to-do list for Silver Bow County, Montana

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 15
Avg. first frost September 7
Soil temp (4") 48°F
Watering Critical
Pest pressure High
Daylight 15.5 hrs
  1. Plant out arugula

    Harden off for 7 days — a little more sun each day — before planting. That's the difference between a seedling that thrives and one that stalls.

  2. Put arugula seeds straight in the ground

    Rake a smooth bed, make a shallow furrow, drop seeds at the spacing on the packet, water gently, walk away.

  3. Start your fall crops: arugula

    Keep young seedlings shaded and moist in summer heat. A row of taller crops works as natural shade.

Looking ahead to July
  • Starting indoors: arugula
  • First harvests: arugula

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Arugula is a fast-growing cool-season green with a peppery, nutty flavor. It is excellent in salads and can be harvested as baby greens or mature leaves.

Silver Bow County, Montana is in USDA Zone 5a. The average last spring frost is June 15 and the first fall frost is September 7, giving you a growing season of approximately 84 days.

At an elevation of 5,305 feet, Silver Bow County receives approximately 14.3 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Arugula to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Arugula successfully. Mulch heavily to conserve soil moisture.

Silver Bow County, MT (Zone 5a) Very short season
84 days
Last Spring Frost June 15
84 growing days
First Fall Frost September 7

Silver Bow County Soil Profile

Soil Type

Loam

Soil pH

6.6-8.3

Drainage

Well Drained

Arugula Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: May 5 Transplant: Jun 9 🍅 Harvest: Jul 14 – Sep 15
Recommended (50%) ✗ May not fit
Start indoors: May 11 Transplant: Jun 15 🍅 Harvest: Jul 20 – Sep 21
Safe Start (90%) ✗ May not fit
Start indoors: May 19 Transplant: Jun 23 🍅 Harvest: Jul 28 – Sep 29

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 Silver Bow County

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

Soil pH

Your soil pH (6.6–8.3) is more alkaline than Arugula prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Silver Bow County is excellent for Arugula — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.5%). Annual compost additions will help Arugula.

How to Plant Arugula

0.5"
Planting Depth
6"
Between Plants
12"
Between Rows

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

Succession Planting Arugula

3
successive plantings in your 84-day season

Sow every 3.4 weeks. Last sowing by Jul 19 to harvest before frost.

For a dedicated fall crop, sow by Jun 29.

Arugula Water Budget

Plant needs
0.6″/week
Rainfall provides
0.7″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Arugula

Arugula needs approximately 0.6 inches of water per week (2.6" per month). Here's how your county's rainfall compares month by month.

Month Arugula Needs Rainfall You Supplement Action
Jan 1.1" 0" ❄️ Dormant
Feb 1" 0" ❄️ Dormant
Mar 1.3" 0" ❄️ Dormant
Apr 1.4" 0" ❄️ Dormant
May 1.5" 0" ❄️ Dormant
Jun 2.6" 0.9" 1.7" 🚿 Regular watering
Jul 2.6" 1.1" 1.5" 🚿 Regular watering
Aug 2.6" 1.8" 0.8" 💧 Light watering
Sep 2.6" 1.1" 1.5" 🚿 Regular watering
Oct 1.1" 0" ❄️ Dormant
Nov 1" 0" ❄️ Dormant
Dec 0.9" 0" ❄️ Dormant

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

Arugula 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.

Arugula needs ~520 GDD — county provides 1,092 GDD Excellent fit

Arugula Planting Timeline — Silver Bow County, MT

Arugula Planting Calendar

Activity When Date Range
Start Indoors May 11 May 11 – May 25
Transplant Outdoors June 15 Jun 15 – Jun 29
Direct Sow June 1 Jun 1 – Jun 22
Harvest July 20 Jul 20 – Sep 21
Fall Sowing June 29 Jun 29 – Jul 13

Plant 0.5" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.6"/week · Natural rainfall sufficient

📅 Days to Maturity

30–50 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 5a

📆 Growing Season

84 days in Silver Bow County

Growing Tips for Arugula in Silver Bow County

Direct sow Arugula outdoors after June 15 in Silver Bow County when soil has warmed and frost danger has passed.

Common pests for Arugula in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Sow seeds directly every 2-3 weeks for continuous harvest. Provide afternoon shade in warm weather to prevent bolting. Harvest outer leaves first to extend production.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Arugula in Silver Bow County, MT?

Silver Bow County is in Zone 5a with an average last frost of June 15. Plan your Arugula planting based on this frost date — see the calendar above for exact timing.

What planting zone is Silver Bow County, MT?

Silver Bow County, Montana is in USDA Hardiness Zone 5a. The average last spring frost is June 15 and first fall frost is September 7.

When should I plant Arugula in Silver Bow County, MT?

In Silver Bow County, MT, plant Arugula after the last frost (around June 15) and before the first frost (around September 7). Best results when soil holds above 50°F.

What growing zone is Silver Bow County, MT for Arugula?

Silver Bow County sits in USDA Zone 5a. Arugula grows reliably in zones 3a through 11b, so it's a good fit here.

Can Arugula grow in Silver Bow County's climate?

Yes — Arugula grows well in Silver Bow County's temperate climate. Silver Bow County averages a 84-day frost-free season, with last frost around June 15 and first frost around September 7.

🌱

Your Silver Bow County Garden Planner — Free

A 22-page printable planner built for Silver Bow County (Zone 5a). 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 Silver Bow County, MT. Local conditions may vary. Last updated: June 2026.

Sources & credits

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