When to Plant Lavender in Cassia County, ID
Lavender is a fragrant perennial herb with silvery foliage and purple flower spikes. It is prized for its essential oils, culinary uses, and ornamental beauty.
Cassia County, Idaho is in USDA Zone 5b. The average last spring frost is May 15 and the first fall frost is October 1, giving you a growing season of approximately 139 days.
At an elevation of 8,089 feet, Cassia County receives approximately 17.5 inches of rainfall annually with predominantly loam soil. Summer highs average 87°F, providing good warmth for Lavender during the growing season. With low rainfall, drip irrigation is essential for growing Lavender successfully. Mulch heavily to conserve soil moisture.
Cassia County Soil Profile
Soil Type
Loam
Soil pH
6.3-8.2
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
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
Lavender Planting Timeline — Cassia County, ID
Lavender Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | May 22 | May 22 – Jun 5 |
| Harvest | August 21 | Aug 21 – Nov 6 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Transplant Outdoors |
| June | Transplant Outdoors |
| July | — |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| November | Harvest |
| December | — |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
Low — drought tolerant
Days to Maturity
90–200 days
Soil pH
6.5 – 8
USDA Zone
Zone 5b
Growing Season
139 days
Growing Tips for Cassia County
Plant in well-drained, sandy soil. Avoid heavy mulching around the crown. Prune after flowering but do not cut into old wood. Lavender resents wet winter conditions.
Companion Planting
Good Companions
Level Up Your Garden
Lavender in Other Locations
Frequently Asked Questions
When should I plant Lavender in Cassia County, ID?
Cassia County is in Zone 5b with an average last frost of May 15. Plan your Lavender planting based on this frost date — see the calendar above for exact timing.
What planting zone is Cassia County, ID?
Cassia County, Idaho is in USDA Hardiness Zone 5b. The average last spring frost is May 15 and first fall frost is October 1.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Cassia 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.