When to Plant Arugula in Lemhi County, ID
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.
Lemhi County, Idaho is in USDA Zone 4b. The average last spring frost is June 9 and the first fall frost is September 14, giving you a growing season of approximately 97 days.
At an elevation of 6,743 feet, Lemhi County receives approximately 12.6 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.
Lemhi County Soil Profile
Soil Type
Loam
Soil pH
6.2-8.2
Drainage
Well Drained
Plant Planting Risk Windows
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 Lemhi County
How your county's soil matches Arugula's growing requirements.
Soil pH
Your soil pH (6.2–8.2) is more alkaline than Arugula prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Lemhi County is excellent for Arugula — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.8%). Annual compost additions will help Arugula.
How to Plant Arugula
Fall planting: Sow 12 weeks before your first frost date for a fall harvest.
Succession Planting Arugula
Sow every 3.4 weeks. Last sowing by Jul 26 to harvest before frost.
For a dedicated fall crop, sow by Jun 22.
Plant Water Budget
Water stress score is 6/10 — 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 | — | 0.8" | 0" | ❄️ Dormant |
| Feb | — | 0.9" | 0" | ❄️ Dormant |
| Mar | — | 1" | 0" | ❄️ Dormant |
| Apr | — | 1.3" | 0" | ❄️ Dormant |
| May | — | 1.4" | 0" | ❄️ Dormant |
| Jun | 2.6" | 0.8" | 1.8" | 🚿 Regular watering |
| Jul | 2.6" | 1.3" | 1.3" | 🚿 Regular watering |
| Aug | 2.6" | 1.3" | 1.3" | 🚿 Regular watering |
| Sep | 2.6" | 1.2" | 1.4" | 🚿 Regular watering |
| Oct | — | 1" | 0" | ❄️ Dormant |
| Nov | — | 1" | 0" | ❄️ Dormant |
| Dec | — | 0.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Jun–Sep in Lemhi 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 Planting Timeline — Lemhi County, ID
Arugula Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 28 | Apr 28 – May 12 |
| Transplant Outdoors | June 9 | Jun 9 – Jun 23 |
| Direct Sow | June 2 | Jun 2 – Jun 23 |
| Harvest | July 14 | Jul 14 – Sep 15 |
| Fall Sowing | June 22 | Jun 22 – Jul 6 |
Plant 0.5" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| 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 · Only during dry spells
📅 Days to Maturity
30–50 days
🧪 Soil pH
Needs 6–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 4b
📆 Growing Season
97 days in Lemhi County
Growing Tips for Arugula in Lemhi County
Direct sow Arugula outdoors after June 09 in Lemhi 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
Check more plant combinations with our Companion Planting Checker →
Arugula in Other Locations
Frequently Asked Questions
When should I plant Arugula in Lemhi County, ID?
Lemhi County is in Zone 4b with an average last frost of June 9. Plan your Arugula planting based on this frost date — see the calendar above for exact timing.
What planting zone is Lemhi County, ID?
Lemhi County, Idaho is in USDA Hardiness Zone 4b. The average last spring frost is June 9 and first fall frost is September 14.
Plan Your Garden with Confidence
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