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When to Plant Basil in Marion County, OR

Basil is a fragrant warm-season herb essential to Italian and Thai cuisines. It comes in many varieties including sweet, Thai, purple, and lemon types.

Marion County, Oregon is in USDA Zone 8a. 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 88ยฐF, providing good warmth for Basil during the growing season. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Basil root diseases.

Marion County, OR (Zone 8a) Moderate season
193 days
Last Spring Frost April 20
193 growing days
First Fall Frost October 30

Marion County Soil Profile

Soil Type

Silt Loam

Soil pH

5.4-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (62 days to spare)
Start indoors: Feb 23 Transplant: Apr 27 🍅 Harvest: Jun 22 – Aug 24
Recommended (50%) ✓ Fits season (60 days to spare)
Start indoors: Mar 2 Transplant: May 4 🍅 Harvest: Jun 29 – Aug 31
Safe Start (90%) ✓ Fits season (66 days to spare)
Start indoors: Mar 21 Transplant: May 23 🍅 Harvest: Jul 18 – Sep 19

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 Basil's growing requirements.

Soil pH

Your soil pH (5.4โ€“6.8) overlaps with Basil's range (6.0โ€“7.0), though not a perfect match.

Soil Texture

The silt loam soil in Marion County is excellent for Basil โ€” good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (4.5%) โ€” Basil will thrive.

How to Plant Basil

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

Succession Planting Basil

4
successive plantings in your 193-day season

Sow every 5.7 weeks. Last sowing by Aug 16 to harvest before frost.

Plant Water Budget

Plant needs
0.6″/week
Rainfall provides
1.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Basil needs ~1,000 GDD — county provides 3,088 GDD Excellent fit

Basil Planting Timeline โ€” Marion County, OR

Basil Planting Calendar

Activity When Date Range
Start Indoors March 2 Mar 2 โ€“ Mar 16
Transplant Outdoors May 4 May 4 โ€“ May 18
Direct Sow April 27 Apr 27 โ€“ May 18
Harvest June 29 Jun 29 โ€“ Aug 31

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March Start Indoors
April Direct Sow
May Transplant Outdoors Direct Sow
June Harvest
July Harvest
August Harvest
September โ€”
October โ€”
November โ€”
December โ€”

Growing Conditions

โ˜€๏ธ Sun

Full Sun (6-8+ hours)

๐Ÿ’ง Water

0.6"/week ยท Natural rainfall sufficient

๐Ÿ“… Days to Maturity

50โ€“75 days

๐Ÿงช Soil pH

Needs 6โ€“7 ยท Your soil: acceptable

๐Ÿ—บ๏ธ USDA Zone

Zone 8a

๐Ÿ“† Growing Season

193 days in Marion County

Growing Tips for Basil in Marion County

Direct sow Basil outdoors after April 20 in Marion County when soil has warmed and frost danger has passed.

General growing tips

Start seeds indoors or direct sow after last frost. Pinch flower buds to extend leaf production. Harvest leaves from the top down, cutting just above a leaf pair.

Recommended Basil Varieties for Marion County

Downy mildew-resistant basil for your humid climate

Prospera (DM-resistant) Amazel Eleonora

Companion Planting

Good Companions

Avoid Planting Near

  • Rue
  • Sage

Level Up Your Garden

๐ŸŒพ Save Your Own Basil Seeds
Life Cycle Annual
Pollination Self-Pollinating
How to Collect Let flower spikes dry brown on the plant.
Storage Store airtight; viable 5 years at 35ยฐF, under 45% humidity.

Isolate 150 ft between varieties. Different basil species can cross.

Frequently Asked Questions

When should I plant Basil in Marion County, OR?

Marion County is in Zone 8a with an average last frost of April 20. Plan your Basil planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Marion County, OR?

Marion County, Oregon is in USDA Hardiness Zone 8a. The average last spring frost is April 20 and first fall frost is October 30.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Marion County gardeners in Zone 8a organize planting dates, track what's growing, and never miss a planting window.

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Marion County, OR. Local conditions may vary. Last updated: April 2026.