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When to Plant Tarragon in Idaho County, ID

Idaho County, Idaho Zone 6b May

May in the garden — Idaho County, Idaho

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Idaho County, Idaho.

Avg. last frost May 29
Avg. first frost September 20
Soil temp (4") 39°F
Watering Moderate
Pest pressure Low
Daylight 14.7 hrs
Before June arrives, get these ready
  • Transplants going out: tarragon

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French tarragon is a perennial herb with slender leaves and a distinctive anise-like flavor essential in French cooking. It does not produce viable seed and must be propagated vegetatively.

Idaho County, Idaho is in USDA Zone 6b. The average last spring frost is May 29 and the first fall frost is September 20, giving you a growing season of approximately 114 days.

At an elevation of 6,736 feet, Idaho County receives approximately 24.5 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Tarragon to ensure they mature before fall.

Idaho County, ID (Zone 6b) Short season
114 days
Last Spring Frost May 29
114 growing days
First Fall Frost September 20

Idaho County Soil Profile

Soil Type

Loam

Soil pH

6.3-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 25 🍅 Harvest: Jul 27 – Oct 5
Recommended (50%) ✗ May not fit
Transplant: Jun 5 🍅 Harvest: Aug 7 – Oct 16
Safe Start (90%) ✗ May not fit
Transplant: Jul 1 🍅 Harvest: Sep 2 – Nov 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 Idaho County

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

Soil pH

Your soil pH (6.3–7.8) overlaps with Tarragon's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

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

How to Plant Tarragon

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

Succession Planting Tarragon

2
successive plantings in your 114-day season

Sow every 6.9 weeks. Last sowing by Jun 22 to harvest before frost.

Plant Water Budget

Plant needs
0.4″/week
Rainfall provides
0.9″/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 Tarragon

Tarragon needs approximately 0.4 inches of water per week (1.7" per month). Here's how your county's rainfall compares month by month.

Month Tarragon Needs Rainfall You Supplement Action
Jan 1.5" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 2.5" 0" ❄️ Dormant
May 1.7" 3.1" 0" ✅ Rainfall sufficient
Jun 1.7" 1.8" 0" ✅ Rainfall sufficient
Jul 1.7" 1.8" 0" ✅ Rainfall sufficient
Aug 1.7" 2.6" 0" ✅ Rainfall sufficient
Sep 1.7" 1.9" 0" ✅ Rainfall sufficient
Oct 2.3" 0" ❄️ Dormant
Nov 1.7" 0" ❄️ Dormant
Dec 1.6" 0" ❄️ Dormant

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

Tarragon 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.

Tarragon needs ~975 GDD — county provides 1,482 GDD Excellent fit

Tarragon Planting Timeline — Idaho County, ID

Tarragon Planting Calendar

Activity When Date Range
Transplant Outdoors June 5 Jun 5 – Jun 19
Harvest August 7 Aug 7 – Oct 16

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April
May
June Transplant Outdoors
July
August Harvest
September Harvest
October Harvest
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.4"/week · Natural rainfall sufficient

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 6b

📆 Growing Season

114 days in Idaho County

Growing Tips for Tarragon in Idaho County

Direct sow Tarragon outdoors after May 29 in Idaho County when soil has warmed and frost danger has passed.

Common pests for Tarragon in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.

General growing tips

Purchase plants or divisions as French tarragon does not grow true from seed. Plant in well-drained soil. Divide every 3-4 years to maintain vigor. Harvest tips regularly for best flavor.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Tarragon in Idaho County, ID?

Idaho County is in Zone 6b with an average last frost of May 29. Plan your Tarragon planting based on this frost date — see the calendar above for exact timing.

What planting zone is Idaho County, ID?

Idaho County, Idaho is in USDA Hardiness Zone 6b. The average last spring frost is May 29 and first fall frost is September 20.

🌱

Your Idaho County Garden Planner — Free

A 24-page printable planner built for Idaho County (Zone 6b). 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 Idaho County, ID. 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.