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When to Plant Basil in Elmore County, ID

Elmore County, Idaho Zone 7a May

May to-do list for Elmore County, Idaho

Each item below is timed to Elmore County, Idaho's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost April 27
Avg. first frost October 14
Soil temp (4") 47°F
Watering High
Pest pressure Low
Daylight 14.5 hrs
  1. Harden off and plant basil

    Your last frost (April 27) has passed. These warm-season crops can handle outdoor soil now.

  2. Put basil seeds straight in the ground

    Sow every 2 weeks for a continuous harvest. A single big planting means a single big glut.

Get ahead of June
  • Starting indoors: basil

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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.

Elmore County, Idaho is in USDA Zone 7a. The average last spring frost is April 27 and the first fall frost is October 14, giving you a growing season of approximately 170 days.

At an elevation of 5,944 feet, Elmore County receives approximately 20.3 inches of rainfall annually with predominantly loam soil. Summer highs average 88°F, providing good warmth for Basil during the growing season.

Elmore County, ID (Zone 7a) Moderate season
170 days
Last Spring Frost April 27
170 growing days
First Fall Frost October 14

Elmore County Soil Profile

Soil Type

Loam

Soil pH

6.7-8.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (43 days to spare)
Start indoors: Feb 24 Transplant: Apr 28 🍅 Harvest: Jun 23 – Aug 25
Recommended (50%) ✓ Fits season (37 days to spare)
Start indoors: Mar 9 Transplant: May 11 🍅 Harvest: Jul 6 – Sep 7
Safe Start (90%) ✓ Fits season (36 days to spare)
Start indoors: Mar 31 Transplant: Jun 2 🍅 Harvest: Jul 28 – Sep 29

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 Elmore County

How your county's soil matches Basil's growing requirements.

Soil pH

Your soil pH (6.7–8.3) is more alkaline than Basil prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Elmore County is excellent for Basil — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Drainage is adequate for Basil.

Organic Matter

Organic matter is moderate (2.7%). Annual compost additions will help Basil.

How to Plant Basil

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

Succession Planting Basil

4
successive plantings in your 170-day season

Sow every 5.7 weeks. Last sowing by Jul 31 to harvest before frost.

Plant Water Budget

Plant needs
0.6″/week
Rainfall provides
0.5″/week
You supply
0.3″/week
Watering frequency 1-2 times/week
Season total 506 gal / 100 sq ft
Drought risk

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 1.6" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 1.7" 0" ❄️ Dormant
Apr 2.6" 1.9" 0.7" 💧 Light watering
May 2.6" 2.7" 0" ✅ Rainfall sufficient
Jun 2.6" 1.6" 1" 💧 Light watering
Jul 2.6" 1.6" 1" 💧 Light watering
Aug 2.6" 1.9" 0.7" 💧 Light watering
Sep 2.6" 1.6" 1" 💧 Light watering
Oct 2.6" 1.7" 0.9" 💧 Light watering
Nov 1.4" 0" ❄️ Dormant
Dec 1.2" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Elmore 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 needs ~1,000 GDD — county provides 2,720 GDD Excellent fit

Basil Planting Timeline — Elmore County, ID

Basil Planting Calendar

Activity When Date Range
Start Indoors March 9 Mar 9 – Mar 23
Transplant Outdoors May 11 May 11 – May 25
Direct Sow May 4 May 4 – May 25
Harvest July 6 Jul 6 – Sep 7

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April
May Transplant Outdoors Direct Sow
June
July Harvest
August Harvest
September Harvest
October
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.6"/week · 1-2 times/week

📅 Days to Maturity

50–75 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 7a

📆 Growing Season

170 days in Elmore County

Growing Tips for Basil in Elmore County

Direct sow Basil outdoors after April 27 in Elmore 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

  • Rue
  • Sage

Check more plant combinations with our Companion Planting Checker →

🌾 Save Your Own Basil Seeds
Life Cycle Annual
Pollination Self-Pollinating
How to Collect Let flower spikes dry brown on the plant.
Storage Store airtight; viable 5 years at 35°F, under 45% humidity.

Isolate 150 ft between varieties. Different basil species can cross.

Frequently Asked Questions

When should I plant Basil in Elmore County, ID?

Elmore County is in Zone 7a with an average last frost of April 27. Plan your Basil planting based on this frost date — see the calendar above for exact timing.

What planting zone is Elmore County, ID?

Elmore County, Idaho is in USDA Hardiness Zone 7a. The average last spring frost is April 27 and first fall frost is October 14.

🌱

Your Elmore County Garden Planner — Free

A 24-page printable planner built for Elmore County (Zone 7a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Elmore County, ID. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.