When to plant Yarrow in Jerome County County,
Jerome County County's short 147-day growing season means one Yarrow planting between May 10 and May 31. No fall crop in Zone 6b.
When to Plant Yarrow in Jerome County, ID
June to-do list for Jerome County, Idaho
Your garden in Jerome County, Idaho is working on a schedule, even when you're not. Here's where you should be this June.
July will be here before you know it — start on
- Starting indoors: yarrow
- First harvests: yarrow
Achillea millefolium (Yarrow) is a tough, drought-tolerant native perennial with aromatic finely-divided foliage and broad flat-topped flower clusters that serve as a landing platform for hundreds of beneficial insect species. Available in white (the species type) and a wide range of cultivars spanning yellow, gold, pink, salmon, and deep red. Spreads by rhizome to form ground-covering colonies; blooms from late spring through midsummer with reblooming into fall if deadheaded. Exceptional in hot, dry sites where other perennials fail.
Jerome County, Idaho is in USDA Zone 6b. The average last spring frost is May 10 and the first fall frost is October 4, giving you a growing season of approximately 147 days.
At an elevation of 6,306 feet, Jerome County receives approximately 13.5 inches of rainfall annually with predominantly loam soil. Summer highs average 85°F, providing good warmth for Yarrow during the growing season. With low rainfall, drip irrigation is essential for growing Yarrow successfully. Mulch heavily to conserve soil moisture.
Jerome County Soil Profile
Soil Type
Loam
Soil pH
6.8-7.9
Drainage
Well Drained
Yarrow 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 Jerome County
How your county's soil matches Yarrow's growing requirements.
Soil pH
Your soil pH (6.8–7.9) is more alkaline than Yarrow prefers (5.5–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Jerome County is excellent for Yarrow — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.8%). Annual compost additions will help Yarrow.
How to Plant Yarrow
Succession Planting Yarrow
Sow every 6.9 weeks. Last sowing by Jul 06 to harvest before frost.
Yarrow Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Yarrow
Yarrow needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.
| Month | Yarrow Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1" | 0" | ❄️ Dormant |
| Feb | — | 0.8" | 0" | ❄️ Dormant |
| Mar | — | 1.3" | 0" | ❄️ Dormant |
| Apr | — | 1.6" | 0" | ❄️ Dormant |
| May | 2.2" | 1.5" | 0.7" | 💧 Light watering |
| Jun | 2.2" | 1" | 1.2" | 🚿 Regular watering |
| Jul | 2.2" | 1.2" | 1" | 💧 Light watering |
| Aug | 2.2" | 1.3" | 0.9" | 💧 Light watering |
| Sep | 2.2" | 1.1" | 1.1" | 🚿 Regular watering |
| Oct | 2.2" | 1.1" | 1.1" | 🚿 Regular watering |
| Nov | — | 0.8" | 0" | ❄️ Dormant |
| Dec | — | 0.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in Jerome County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Yarrow 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.
Yarrow Planting Timeline — Jerome County, ID
Yarrow Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 8 | Mar 8 – Mar 22 |
| Transplant Outdoors | May 17 | May 17 – May 31 |
| Direct Sow | May 10 | May 10 – May 31 |
| Bloom | July 26 | Jul 26 – Nov 22 |
· 18" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | — |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Bloom |
| August | Bloom |
| September | Bloom |
| October | Bloom |
| November | Bloom |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Only during dry spells
📅 Days to Maturity
60–90 days
🧪 Soil pH
Needs 5.5–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 6b
📆 Growing Season
147 days in Jerome County
Growing Tips for Yarrow in Jerome County
Direct sow Yarrow outdoors after May 10 in Jerome County when soil has warmed and frost danger has passed.
Common pests for Yarrow in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.
Jerome County receives only 14" of rain annually. Yarrow needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Start seeds indoors 8–10 weeks before last frost; seeds need light for germination — press onto soil surface, do not cover. Direct sow after last frost or divide established clumps in spring or fall. Thrives in poor, well-drained soil — rich soil and high fertility cause floppy stems and reduce flower count. Avoid overwatering; excellent drought tolerance once established. Deadhead spent clusters to encourage rebloom. Divide every 2–3 years to prevent center die-out and control spread. Year 2+ plants bloom most heavily; first-year plants may produce limited flowers. Dried flowers retain color well for arrangements.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Yarrow in Other Locations
Frequently Asked Questions
When should I plant Yarrow in Jerome County, ID?
Jerome County is in Zone 6b with an average last frost of May 10. Plan your Yarrow planting based on this frost date — see the calendar above for exact timing.
What planting zone is Jerome County, ID?
Jerome County, Idaho is in USDA Hardiness Zone 6b. The average last spring frost is May 10 and first fall frost is October 4.
When should I plant Yarrow in Jerome County, ?
In Jerome County, , plant Yarrow after the last frost (around May 10) and before the first frost (around October 4). Best results when soil holds above 50°F.
What growing zone is Jerome County, for Yarrow?
Jerome County sits in USDA Zone 6b. Yarrow grows reliably in zones 3a through 9b, so it's a good fit here.
Can Yarrow grow in Jerome County's climate?
Yes — Yarrow grows well in Jerome County's temperate climate. Jerome County averages a 147-day frost-free season, with last frost around May 10 and first frost around October 4.
Your Jerome County Garden Planner — Free
A 22-page printable planner built for Jerome County (Zone 6b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.