When to Plant Borage in Kern County, CA
Borage is a self-seeding annual herb with star-shaped blue flowers that attract pollinators. Its leaves have a cucumber-like flavor and the flowers are edible.
Kern County, California is in USDA Zone 9a. The average last spring frost is February 28 and the first fall frost is November 29, giving you a growing season of approximately 274 days.
At an elevation of 389 feet, Kern County receives approximately 16.9 inches of rainfall annually with predominantly loam soil. Summer highs average 102°F, so Borage may need afternoon shade and extra watering during peak heat. With low rainfall, drip irrigation is essential for growing Borage successfully. Mulch heavily to conserve soil moisture.
Kern County Soil Profile
Soil Type
Loam
Soil pH
6.2-7.7
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.
Soil Compatibility in Kern County
How your county's soil matches Borage's growing requirements.
Soil pH
Your soil pH (6.2–7.7) overlaps with Borage's range (6.0–7.0), though not a perfect match.
Soil Texture
The loam soil in Kern County is excellent for Borage — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Borage.
Organic Matter
Organic matter is moderate (2.3%). Annual compost additions will help Borage.
How to Plant Borage
Fall planting: Sow 8 weeks before your first frost date for a fall harvest.
Succession Planting Borage
Sow every 5.7 weeks. Last sowing by Sep 30 to harvest before frost.
For a dedicated fall crop, sow by Oct 04.
Plant Water Budget
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Borage
Borage 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 | Borage Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 3.9" | 0" | ❄️ Dormant |
| Feb | 2.2" | 3.4" | 0" | ✅ Rainfall sufficient |
| Mar | 2.2" | 2.4" | 0" | ✅ Rainfall sufficient |
| Apr | 2.2" | 1.2" | 1" | 💧 Light watering |
| May | 2.2" | 0.5" | 1.7" | 🚿 Regular watering |
| Jun | 2.2" | 0.1" | 2.1" | 🚿 Regular watering |
| Jul | 2.2" | 0" | 2.2" | 🚿 Regular watering |
| Aug | 2.2" | 0" | 2.2" | 🚿 Regular watering |
| Sep | 2.2" | 0.2" | 2" | 🚿 Regular watering |
| Oct | 2.2" | 0.7" | 1.5" | 🚿 Regular watering |
| Nov | 2.2" | 1.7" | 0.5" | 💧 Light watering |
| Dec | — | 2.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Feb–Nov in Kern County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Borage 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.
Borage Planting Timeline — Kern County, CA
Borage Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | January 31 | Jan 31 – Feb 14 |
| Transplant Outdoors | February 21 | Feb 21 – Mar 7 |
| Direct Sow | February 7 | Feb 7 – Feb 28 |
| Harvest | April 18 | Apr 18 – Jun 6 |
| Fall Sowing | October 4 | Oct 4 – Oct 18 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Start Indoors |
| February | Start Indoors Transplant Outdoors Direct Sow |
| March | Transplant Outdoors |
| April | Harvest |
| May | Harvest |
| June | Harvest |
| July | — |
| August | — |
| September | — |
| October | Fall Sowing |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · 1-2 times/week
📅 Days to Maturity
50–60 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 9a
📆 Growing Season
274 days in Kern County
Growing Tips for Borage in Kern County
Direct sow Borage outdoors after February 28 in Kern County when soil has warmed and frost danger has passed.
With summer highs reaching 102°F in Kern County, provide afternoon shade for Borage and water deeply in the morning.
General growing tips
Direct sow in spring as borage does not transplant well. Allow some plants to go to seed for next year. Young leaves are best; older leaves become bristly.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Borage in Other Locations
Frequently Asked Questions
When should I plant Borage in Kern County, CA?
Kern County is in Zone 9a with an average last frost of February 28. Plan your Borage planting based on this frost date — see the calendar above for exact timing.
What planting zone is Kern County, CA?
Kern County, California is in USDA Hardiness Zone 9a. The average last spring frost is February 28 and first fall frost is November 29.
Plan Your Garden with Confidence
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