When to Plant Basil in Slope County, ND
Basil is a fragrant warm-season herb essential to Italian and Thai cuisines. It comes in many varieties including sweet, Thai, purple, and lemon types.
Slope County, North Dakota is in USDA Zone 4a. The average last spring frost is May 15 and the first fall frost is September 24, giving you a growing season of approximately 132 days.
At an elevation of 1,230 feet, Slope County receives approximately 31.4 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Basil to ensure they mature before fall.
Slope County Soil Profile
Soil Type
Loam
Soil pH
6.7-7.6
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 Slope County
How your county's soil matches Basil's growing requirements.
Soil pH
Your soil pH (6.7–7.6) is more alkaline than Basil prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Slope County is excellent for Basil — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Basil.
Organic Matter
Organic matter is excellent (4.2%) — Basil will thrive.
How to Plant Basil
Succession Planting Basil
Sow every 5.7 weeks. Last sowing by Jul 11 to harvest before frost.
Plant Water Budget
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Basil
Basil needs approximately 0.6 inches of water per week (2.6" per month). Here's how your county's rainfall compares month by month.
| Month | Basil Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 2.4" | 0" | ❄️ Dormant |
| Feb | — | 1.9" | 0" | ❄️ Dormant |
| Mar | — | 3.1" | 0" | ❄️ Dormant |
| Apr | — | 2.9" | 0" | ❄️ Dormant |
| May | 2.6" | 3.3" | 0" | ✅ Rainfall sufficient |
| Jun | 2.6" | 2.3" | 0.3" | 💧 Light watering |
| Jul | 2.6" | 3.1" | 0" | ✅ Rainfall sufficient |
| Aug | 2.6" | 3" | 0" | ✅ Rainfall sufficient |
| Sep | 2.6" | 2.3" | 0.3" | 💧 Light watering |
| Oct | — | 2.7" | 0" | ❄️ Dormant |
| Nov | — | 2.3" | 0" | ❄️ Dormant |
| Dec | — | 2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Slope County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Basil 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.
Basil Planting Timeline — Slope County, ND
Basil Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 20 | Mar 20 – Apr 3 |
| Transplant Outdoors | June 5 | Jun 5 – Jun 19 |
| Direct Sow | May 22 | May 22 – Jun 12 |
| Harvest | July 31 | Jul 31 – Oct 2 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors |
| May | Direct Sow |
| June | Transplant Outdoors Direct Sow |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.6"/week · Natural rainfall sufficient
📅 Days to Maturity
50–75 days
🧪 Soil pH
Needs 6–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 4a
📆 Growing Season
132 days in Slope County
Growing Tips for Basil in Slope County
Direct sow Basil outdoors after May 15 in Slope County when soil has warmed and frost danger has passed.
General growing tips
Start seeds indoors or direct sow after last frost. Pinch flower buds to extend leaf production. Harvest leaves from the top down, cutting just above a leaf pair.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Isolate 150 ft between varieties. Different basil species can cross.
Basil in Other Locations
Frequently Asked Questions
When should I plant Basil in Slope County, ND?
Slope County is in Zone 4a with an average last frost of May 15. Plan your Basil planting based on this frost date — see the calendar above for exact timing.
What planting zone is Slope County, ND?
Slope County, North Dakota is in USDA Hardiness Zone 4a. The average last spring frost is May 15 and first fall frost is September 24.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Slope County gardeners in Zone 4a organize planting dates, track what's growing, and never miss a planting window.
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