When to plant Yarrow in Lassen County, CA
Plant Yarrow in Lassen County, between May 28 and June 18 — the only viable window. Zone 7a's short season (124 frost-free days) rules out a fall crop.
When to Plant Yarrow in Lassen County, CA
Lassen County, California gardeners: here's your July plan
If you only do a handful of things in the garden this July, make it these. They're sequenced around your zone's frost timing.
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Indoor seed-starting week for yarrow
These need a head start before your last frost (May 28). Sow into cells now so you're ready to transplant in a few weeks.
To set up a strong August, finish these tasks
- 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.
Lassen County, California is in USDA Zone 7a. The average last spring frost is May 28 and the first fall frost is September 29, giving you a growing season of approximately 124 days.
At an elevation of 1,854 feet, Lassen County receives approximately 43.7 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Yarrow to ensure they mature before fall.
Lassen County Soil Profile
Soil Type
Loam
Soil pH
6.1-7.5
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 Lassen County
How your county's soil matches Yarrow's growing requirements.
Soil pH
Your soil pH (6.1–7.5) overlaps with Yarrow's range (5.5–7.0), though not a perfect match.
Soil Texture
The loam soil in Lassen County is excellent for Yarrow — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.3%). Annual compost additions will help Yarrow.
How to Plant Yarrow
Succession Planting Yarrow
Sow every 6.9 weeks. Last sowing by Jul 01 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 | — | 9.2" | 0" | ❄️ Dormant |
| Feb | — | 9.8" | 0" | ❄️ Dormant |
| Mar | — | 7.7" | 0" | ❄️ Dormant |
| Apr | — | 3.2" | 0" | ❄️ Dormant |
| May | 2.2" | 1" | 1.2" | 🚿 Regular watering |
| Jun | 2.2" | 0.2" | 2" | 🚿 Regular watering |
| Jul | 2.2" | 0" | 2.2" | 🚿 Regular watering |
| Aug | 2.2" | 0" | 2.2" | 🚿 Regular watering |
| Sep | 2.2" | 0.5" | 1.7" | 🚿 Regular watering |
| Oct | — | 1.7" | 0" | ❄️ Dormant |
| Nov | — | 3.9" | 0" | ❄️ Dormant |
| Dec | — | 6.5" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Lassen 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 — Lassen County, CA
Yarrow Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 26 | Mar 26 – Apr 9 |
| Transplant Outdoors | June 4 | Jun 4 – Jun 18 |
| Direct Sow | May 28 | May 28 – Jun 18 |
| Bloom | August 6 | Aug 6 – Dec 17 |
· 18" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors |
| May | Direct Sow |
| June | Transplant Outdoors Direct Sow |
| July | — |
| August | Bloom |
| September | Bloom |
| October | Bloom |
| November | Bloom |
| December | Bloom |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Natural rainfall sufficient
📅 Days to Maturity
60–90 days
🧪 Soil pH
Needs 5.5–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 7a
📆 Growing Season
124 days in Lassen County
Growing Tips for Yarrow in Lassen County
Direct sow Yarrow outdoors after May 28 in Lassen 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.
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 Lassen County, CA?
Lassen County is in Zone 7a with an average last frost of May 28. Plan your Yarrow planting based on this frost date — see the calendar above for exact timing.
What planting zone is Lassen County, CA?
Lassen County, California is in USDA Hardiness Zone 7a. The average last spring frost is May 28 and first fall frost is September 29.
When should I plant Yarrow in Lassen County, CA?
In Lassen County, CA, plant Yarrow after the last frost (around May 28) and before the first frost (around September 29). Best results when soil holds above 50°F.
What growing zone is Lassen County, CA for Yarrow?
Lassen County sits in USDA Zone 7a. Yarrow grows reliably in zones 3a through 9b, so it's a good fit here.
Can Yarrow grow in Lassen County's climate?
Yes — Yarrow grows well in Lassen County's temperate climate. Lassen County averages a 124-day frost-free season, with last frost around May 28 and first frost around September 29.
Your Lassen County Garden Planner — Free
A 22-page printable planner built for Lassen County (Zone 7a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.