When to plant Borage in Custer County, ID
For Custer County, gardeners: plant Borage June 4 through June 25 once soil reads 50°F. A second sowing from June 27 to July 11 extends the harvest into fall.
When to Plant Borage in Custer County, ID
Your July gardening checklist
Your Custer County, Idaho garden is entering a new phase. Here's what's on the schedule for July and why each task matters now.
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Start borage under lights
Your window is short. These crops want several weeks of indoor growth before they go outside.
August prep starts now
- First harvests: borage
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.
Custer County, Idaho is in USDA Zone 5b. The average last spring frost is June 18 and the first fall frost is September 5, giving you a growing season of approximately 79 days.
At an elevation of 5,189 feet, Custer County receives approximately 20.6 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Borage to ensure they mature before fall.
Custer County Soil Profile
Soil Type
Loam
Soil pH
6.3-8
Drainage
Well Drained
Borage 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 Custer County
How your county's soil matches Borage's growing requirements.
Soil pH
Your soil pH (6.3–8.0) is more alkaline than Borage prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Custer County is excellent for Borage — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.3%). Annual compost additions will help Borage.
How to Plant Borage
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Borage Water Budget
Water stress score is 6/10 — 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 | — | 1.3" | 0" | ❄️ Dormant |
| Feb | — | 1.3" | 0" | ❄️ Dormant |
| Mar | — | 1.7" | 0" | ❄️ Dormant |
| Apr | — | 2.4" | 0" | ❄️ Dormant |
| May | — | 2.3" | 0" | ❄️ Dormant |
| Jun | 2.2" | 1.5" | 0.7" | 💧 Light watering |
| Jul | 2.2" | 2" | 0.2" | 💧 Light watering |
| Aug | 2.2" | 2.1" | 0.1" | 💧 Light watering |
| Sep | 2.2" | 1.7" | 0.5" | 💧 Light watering |
| Oct | — | 1.6" | 0" | ❄️ Dormant |
| Nov | — | 1.4" | 0" | ❄️ Dormant |
| Dec | — | 1.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Jun–Sep in Custer 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 — Custer County, ID
Borage Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | May 14 | May 14 – May 28 |
| Transplant Outdoors | June 11 | Jun 11 – Jun 25 |
| Direct Sow | June 4 | Jun 4 – Jun 25 |
| Harvest | August 6 | Aug 6 – Sep 24 |
| Fall Sowing | June 27 | Jun 27 – Jul 11 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Start Indoors |
| June | Transplant Outdoors Direct Sow Fall Sowing |
| July | Fall Sowing |
| August | Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Natural rainfall sufficient
📅 Days to Maturity
50–60 days
🧪 Soil pH
Needs 6–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 5b
📆 Growing Season
79 days in Custer County
Growing Tips for Borage in Custer County
Direct sow Borage outdoors after June 18 in Custer County when soil has warmed and frost danger has passed.
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 Custer County, ID?
Custer County is in Zone 5b with an average last frost of June 18. Plan your Borage planting based on this frost date — see the calendar above for exact timing.
What planting zone is Custer County, ID?
Custer County, Idaho is in USDA Hardiness Zone 5b. The average last spring frost is June 18 and first fall frost is September 5.
When should I plant Borage in Custer County, ID?
In Custer County, ID, plant Borage after the last frost (around June 18) and before the first frost (around September 5). Best results when soil holds above 50°F.
What growing zone is Custer County, ID for Borage?
Custer County sits in USDA Zone 5b. Borage grows reliably in zones 3a through 11b, so it's a good fit here.
Can Borage grow in Custer County's climate?
Yes — Borage grows well in Custer County's temperate climate. Custer County averages a 79-day frost-free season, with last frost around June 18 and first frost around September 5.
Your Custer County Garden Planner — Free
A 22-page printable planner built for Custer County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.