When to plant Borage in Castleton,
For Borage in Castleton, the safe spring window opens around April 7 and closes around April 28. Last expected frost is April 21, first fall frost October 12, giving a 174-day growing season. A second sowing from August 3 to August 17 extends the harvest into fall.
When to Plant Borage in Castleton, IL
What to do in June
Each item below is timed to Castleton, IL's frost dates and soil temperatures. Skip nothing, stress about nothing.
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Bring in the borage
The more you pick, the more the plant produces. Letting fruit overripen tells the plant it's time to stop.
To set up a strong July, finish these tasks
- 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.
Castleton, Illinois is in USDA Zone 5b. The average last spring frost is April 21 and the first fall frost is October 12, giving you a growing season of approximately 174 days.
At an elevation of 1,071 feet, Stark County receives approximately 33.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Borage to ensure they mature before fall.
Castleton Soil Profile
Soil Type
Silt Loam
Soil pH
6-6.9
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 Castleton
How your county's soil matches Borage's growing requirements.
Soil pH
Your soil pH (6.0–6.9) is within Borage's preferred range (6.0–7.0).
Soil Texture
The silt loam soil in Stark County is excellent for Borage — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.8%) — Borage will thrive.
How to Plant Borage
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Succession Planting Borage
Sow every 5.7 weeks. Last sowing by Aug 13 to harvest before frost.
For a dedicated fall crop, sow by Aug 03.
Borage Water Budget
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 | — | 1.4" | 0" | ❄️ Dormant |
| Feb | — | 1.5" | 0" | ❄️ Dormant |
| Mar | — | 2.7" | 0" | ❄️ Dormant |
| Apr | 2.2" | 3.5" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 4.1" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 4.1" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 3.5" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 3.3" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 2.8" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 2.9" | 0" | ✅ Rainfall sufficient |
| Nov | — | 2.3" | 0" | ❄️ Dormant |
| Dec | — | 1.7" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Stark 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 — Castleton, IL
Borage Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 17 | Mar 17 – Mar 31 |
| Transplant Outdoors | April 14 | Apr 14 – Apr 28 |
| Direct Sow | April 7 | Apr 7 – Apr 28 |
| Harvest | June 9 | Jun 9 – Jul 28 |
| Fall Sowing | August 3 | Aug 3 – Aug 17 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Transplant Outdoors Direct Sow |
| May | — |
| June | Harvest |
| July | Harvest |
| August | Fall Sowing |
| September | — |
| 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: ideal
🗺️ USDA Zone
Zone 5b
📆 Growing Season
174 days in Stark County
Growing Tips for Borage in Castleton
Direct sow Borage outdoors after April 21 in Stark 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
When should I plant Borage in Castleton, ?
In Castleton, , plant Borage after the last frost (around April 21) and before the first frost (around October 12). Best results when soil holds above 50°F.
What growing zone is Castleton, for Borage?
Castleton sits in USDA Zone 5b. Borage grows reliably in zones 3a through 11b, so it's a good fit here.
Can Borage grow in Castleton's climate?
Yes — Borage grows well in Castleton's temperate climate. Castleton averages a 174-day frost-free season, with last frost around April 21 and first frost around October 12.
Your Stark County Garden Planner — Free
A 22-page printable planner built for Stark 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.