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When to Plant Tarragon in Wahkiakum County, WA

Wahkiakum County, Washington Zone 8b May

May to-do list for Wahkiakum County, Washington

We've pulled the most time-sensitive tasks for Wahkiakum County, Washington this May and put them front and centre. Tackle them in order.

Avg. last frost April 13
Avg. first frost November 4
Soil temp (4") 69°F
Watering High
Pest pressure High
Daylight 14.8 hrs
To set up a strong June, finish these tasks
  • First harvests: 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.

Wahkiakum County, Washington is in USDA Zone 8b. The average last spring frost is April 13 and the first fall frost is November 4, giving you a growing season of approximately 205 days.

At an elevation of 180 feet, Wahkiakum County receives approximately 35.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Tarragon during the growing season.

Wahkiakum County, WA (Zone 8b) Long season
205 days
Last Spring Frost April 13
205 growing days
First Fall Frost November 4

Wahkiakum County Soil Profile

Soil Type

Silt Loam

Soil pH

5.4-6.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (70 days to spare)
Transplant: Apr 9 🍅 Harvest: Jun 11 – Aug 20
Recommended (50%) ✓ Fits season (65 days to spare)
Transplant: Apr 20 🍅 Harvest: Jun 22 – Aug 31
Safe Start (90%) ✓ Fits season (77 days to spare)
Transplant: May 7 🍅 Harvest: Jul 9 – Sep 17

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 Wahkiakum County

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

Soil pH

Your soil pH (5.4–6.3) is more acidic than Tarragon prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.6%) — Tarragon will thrive.

How to Plant Tarragon

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

Succession Planting Tarragon

4
successive plantings in your 205-day season

Sow every 6.9 weeks. Last sowing by Aug 06 to harvest before frost.

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

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 4.9" 0" ❄️ Dormant
Feb 4.2" 0" ❄️ Dormant
Mar 3.6" 0" ❄️ Dormant
Apr 1.7" 2.6" 0" ✅ Rainfall sufficient
May 1.7" 1.8" 0" ✅ Rainfall sufficient
Jun 1.7" 1.4" 0.3" 💧 Light watering
Jul 1.7" 0.6" 1.1" 🚿 Regular watering
Aug 1.7" 0.7" 1" 🚿 Regular watering
Sep 1.7" 1.4" 0.3" 💧 Light watering
Oct 1.7" 2.9" 0" ✅ Rainfall sufficient
Nov 1.7" 5.8" 0" ✅ Rainfall sufficient
Dec 5.3" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Nov in Wahkiakum 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 ~1,031 GDD — county provides 2,818 GDD Excellent fit

Tarragon Planting Timeline — Wahkiakum County, WA

Tarragon Planting Calendar

Activity When Date Range
Transplant Outdoors April 20 Apr 20 – May 4
Harvest June 22 Jun 22 – Aug 31

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

Month-by-Month Timeline

MonthActivities
January
February
March
April Transplant Outdoors
May Transplant Outdoors
June Harvest
July Harvest
August Harvest
September
October
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: too_acidic

🗺️ USDA Zone

Zone 8b

📆 Growing Season

205 days in Wahkiakum County

Growing Tips for Tarragon in Wahkiakum County

Direct sow Tarragon outdoors after April 13 in Wahkiakum 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 Wahkiakum County, WA?

Wahkiakum County is in Zone 8b with an average last frost of April 13. Plan your Tarragon planting based on this frost date — see the calendar above for exact timing.

What planting zone is Wahkiakum County, WA?

Wahkiakum County, Washington is in USDA Hardiness Zone 8b. The average last spring frost is April 13 and first fall frost is November 4.

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Your Wahkiakum County Garden Planner — Free

A 24-page printable planner built for Wahkiakum County (Zone 8b). 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 Wahkiakum County, WA. 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.