When to Plant Thai Basil in Union County, OR
Thai basil has a distinctive anise-licorice flavor with sturdy purple stems and small leaves. It is essential in Thai, Vietnamese, and other Southeast Asian cuisines.
Union County, Oregon is in USDA Zone 5b. The average last spring frost is May 12 and the first fall frost is September 26, giving you a growing season of approximately 137 days.
At an elevation of 2,751 feet, Union County receives approximately 23.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Thai Basil during the growing season.
Union County Soil Profile
Soil Type
Silt Loam
Soil pH
5.2-6.6
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.
Plant Water Budget
Thai Basil Planting Timeline — Union County, OR
Thai Basil Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 24 | Mar 24 – Apr 7 |
| Transplant Outdoors | May 26 | May 26 – Jun 9 |
| Direct Sow | May 19 | May 19 – Jun 9 |
| Harvest | July 21 | Jul 21 – Sep 22 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors |
| May | Transplant Outdoors Direct Sow |
| June | Transplant Outdoors Direct Sow |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
Moderate — regular watering
Days to Maturity
50–75 days
Soil pH
6 – 7
USDA Zone
Zone 5b
Growing Season
137 days
Growing Tips for Union County
Start seeds indoors or direct sow after last frost. Thai basil holds up better to heat in cooking than sweet basil. Pinch flowers to prolong leaf production.
Companion Planting
Good Companions
Avoid Planting Near
Level Up Your Garden
Thai Basil in Other Locations
Frequently Asked Questions
When should I plant Thai Basil in Union County, OR?
Union County is in Zone 5b with an average last frost of May 12. Plan your Thai Basil planting based on this frost date — see the calendar above for exact timing.
What planting zone is Union County, OR?
Union County, Oregon is in USDA Hardiness Zone 5b. The average last spring frost is May 12 and first fall frost is September 26.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Union County gardeners in Zone 5b 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.