When to Plant Tarragon in Marion County, OR
May in Marion County, Oregon — your action list
May is a pivotal month for Marion County, Oregon gardens. Focus on these tasks first and you'll set up the rest of the season for success.
Looking ahead to June
- First harvests: tarragon
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.
Marion County, Oregon is in USDA Zone 8b. The average last spring frost is April 20 and the first fall frost is October 30, giving you a growing season of approximately 193 days.
At an elevation of 422 feet, Marion County receives approximately 50.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88°F, providing good warmth for Tarragon during the growing season. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Tarragon root diseases.
Marion County Soil Profile
Soil Type
Silt Loam
Soil pH
5.4-6.8
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 Marion County
How your county's soil matches Tarragon's growing requirements.
Soil pH
Your soil pH (5.4–6.8) overlaps with Tarragon's range (6.0–7.5), though not a perfect match.
Soil Texture
The silt loam soil in Marion County is excellent for Tarragon — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.5%) — Tarragon will thrive.
How to Plant Tarragon
Succession Planting Tarragon
Sow every 6.9 weeks. Last sowing by Aug 01 to harvest before frost.
Plant Water Budget
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 | — | 6.9" | 0" | ❄️ Dormant |
| Feb | — | 5.1" | 0" | ❄️ Dormant |
| Mar | — | 4.9" | 0" | ❄️ Dormant |
| Apr | 1.7" | 3.8" | 0" | ✅ Rainfall sufficient |
| May | 1.7" | 2.8" | 0" | ✅ Rainfall sufficient |
| Jun | 1.7" | 2" | 0" | ✅ Rainfall sufficient |
| Jul | 1.7" | 0.8" | 0.9" | 🚿 Regular watering |
| Aug | 1.7" | 1" | 0.7" | 💧 Light watering |
| Sep | 1.7" | 1.9" | 0" | ✅ Rainfall sufficient |
| Oct | 1.7" | 4.2" | 0" | ✅ Rainfall sufficient |
| Nov | — | 8.2" | 0" | ❄️ Dormant |
| Dec | — | 9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Marion 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 Planting Timeline — Marion County, OR
Tarragon Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | April 27 | Apr 27 – May 11 |
| Harvest | June 29 | Jun 29 – Sep 7 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Transplant Outdoors |
| May | Transplant Outdoors |
| June | Harvest |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| 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: acceptable
🗺️ USDA Zone
Zone 8b
📆 Growing Season
193 days in Marion County
Growing Tips for Tarragon in Marion County
Direct sow Tarragon outdoors after April 20 in Marion 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 →
Tarragon in Other Locations
Frequently Asked Questions
When should I plant Tarragon in Marion County, OR?
Marion County is in Zone 8b with an average last frost of April 20. Plan your Tarragon planting based on this frost date — see the calendar above for exact timing.
What planting zone is Marion County, OR?
Marion County, Oregon is in USDA Hardiness Zone 8b. The average last spring frost is April 20 and first fall frost is October 30.
Your Marion County Garden Planner — Free
A 24-page printable planner built for Marion 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.