When to Plant Borage in St. Louis County, MN
This month in St. Louis County, Minnesota
May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in St. Louis County, Minnesota.
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Plant out borage
Frost risk is low now in St. Louis County, Minnesota. If you've been covering beds overnight, you can stop.
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Scatter borage into prepared beds
Keep the top inch of soil moist until germination — a gentle morning watering for 5–7 days does the job.
Get ahead of June
- Fall sowing: 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.
St. Louis County, Minnesota is in USDA Zone 3b. The average last spring frost is June 2 and the first fall frost is September 10, giving you a growing season of approximately 100 days.
At an elevation of 531 feet, St. Louis County receives approximately 36.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 78°F, so choose short-season varieties of Borage to ensure they mature before fall.
St. Louis County Soil Profile
Soil Type
Silt Loam
Soil pH
6-7
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 St. Louis County
How your county's soil matches Borage's growing requirements.
Soil pH
Your soil pH (6.0–7.0) is within Borage's preferred range (6.0–7.0).
Soil Texture
The silt loam soil in St. Louis County is excellent for Borage — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Borage.
Organic Matter
Organic matter is excellent (4.0%) — Borage will thrive.
How to Plant Borage
Fall planting: Sow 12 weeks before your first frost date for a fall harvest.
Succession Planting Borage
Sow every 5.7 weeks. Last sowing by Jul 12 to harvest before frost.
For a dedicated fall crop, sow by Jun 18.
Plant 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 | — | 1.6" | 0" | ❄️ Dormant |
| Feb | — | 1.7" | 0" | ❄️ Dormant |
| Mar | — | 2.7" | 0" | ❄️ Dormant |
| Apr | — | 3.2" | 0" | ❄️ Dormant |
| May | — | 3.9" | 0" | ❄️ Dormant |
| Jun | 2.2" | 5.1" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 4.4" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 3.7" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 3.1" | 0" | ✅ Rainfall sufficient |
| Oct | — | 2.8" | 0" | ❄️ Dormant |
| Nov | — | 2.3" | 0" | ❄️ Dormant |
| Dec | — | 1.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Jun–Sep in St. Louis 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 — St. Louis County, MN
Borage Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 21 | Apr 21 – May 5 |
| Transplant Outdoors | May 26 | May 26 – Jun 9 |
| Direct Sow | May 26 | May 26 – Jun 16 |
| Harvest | July 21 | Jul 21 – Sep 8 |
| Fall Sowing | June 18 | Jun 18 – Jul 2 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| May | Start Indoors Transplant Outdoors Direct Sow |
| June | Transplant Outdoors Direct Sow Fall Sowing |
| July | Fall Sowing Harvest |
| 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: ideal
🗺️ USDA Zone
Zone 3b
📆 Growing Season
100 days in St. Louis County
Growing Tips for Borage in St. Louis County
Direct sow Borage outdoors after June 02 in St. Louis 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 St. Louis County, MN?
St. Louis County is in Zone 3b with an average last frost of June 2. Plan your Borage planting based on this frost date — see the calendar above for exact timing.
What planting zone is St. Louis County, MN?
St. Louis County, Minnesota is in USDA Hardiness Zone 3b. The average last spring frost is June 2 and first fall frost is September 10.
Your St. Louis County Garden Planner — Free
A 24-page printable planner built for St. Louis County (Zone 3b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.