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When to Plant Tarragon in Owyhee County, ID

Owyhee County, Idaho Zone 7a May

Your May game plan for Owyhee County, Idaho

Each item below is timed to Owyhee County, Idaho's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost June 9
Avg. first frost September 20
Soil temp (4") 51°F
Watering High
Pest pressure Low
Daylight 14.4 hrs
A few tasks this May that'll pay off in June
  • 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.

Owyhee County, Idaho is in USDA Zone 7a. The average last spring frost is June 9 and the first fall frost is September 20, giving you a growing season of approximately 103 days.

At an elevation of 4,621 feet, Owyhee County receives approximately 18.1 inches of rainfall annually with predominantly loam soil. Summer highs average 90°F, providing good warmth for Tarragon during the growing season. With low rainfall, drip irrigation is essential for growing Tarragon successfully. Mulch heavily to conserve soil moisture.

Owyhee County, ID (Zone 7a) Short season
103 days
Last Spring Frost June 9
103 growing days
First Fall Frost September 20
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Owyhee 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: Jun 8 🍅 Harvest: Aug 10 – Oct 19
Recommended (50%) ✗ May not fit
Transplant: Jun 16 🍅 Harvest: Aug 18 – Oct 27
Safe Start (90%) ✗ May not fit
Transplant: Jun 26 🍅 Harvest: Aug 28 – Nov 6

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 Owyhee 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 Owyhee County is excellent for Tarragon — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.7%). Annual compost additions will help Tarragon.

How to Plant Tarragon

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

Plant Water Budget

Plant needs
0.4″/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 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 1.1" 0" ❄️ Dormant
Feb 1.1" 0" ❄️ Dormant
Mar 1.7" 0" ❄️ Dormant
Apr 2" 0" ❄️ Dormant
May 2.3" 0" ❄️ Dormant
Jun 1.7" 1.4" 0.3" 💧 Light watering
Jul 1.7" 1.8" 0" ✅ Rainfall sufficient
Aug 1.7" 1.7" 0" ✅ Rainfall sufficient
Sep 1.7" 1.3" 0.4" 💧 Light watering
Oct 1.6" 0" ❄️ Dormant
Nov 1.2" 0" ❄️ Dormant
Dec 1" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Sep in Owyhee 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 ~1,312 GDD — county provides 1,802 GDD Excellent fit

Tarragon Planting Timeline — Owyhee County, ID

Tarragon Planting Calendar

Activity When Date Range
Transplant Outdoors June 16 Jun 16 – Jun 30
Harvest August 18 Aug 18 – Oct 27

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
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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 7a

📆 Growing Season

103 days in Owyhee County

Growing Tips for Tarragon in Owyhee County

Direct sow Tarragon outdoors after June 09 in Owyhee County when soil has warmed and frost danger has passed.

Your 103.0-day growing season in Owyhee County is tight for Tarragon (60.0-90.0 days to maturity). Start indoors and choose early-maturing varieties.

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 Owyhee County, ID?

Owyhee County is in Zone 7a with an average last frost of June 9. Plan your Tarragon planting based on this frost date — see the calendar above for exact timing.

What planting zone is Owyhee County, ID?

Owyhee County, Idaho is in USDA Hardiness Zone 7a. The average last spring frost is June 9 and first fall frost is September 20.

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Your Owyhee County Garden Planner — Free

A 24-page printable planner built for Owyhee County (Zone 7a). 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 Owyhee 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.