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When to plant Basil in Jerome County County,

In Jerome County County, Basil is a spring-only crop. Plant May 17–June 7 once soil hits 50°F.

When to Plant Basil in Jerome County, ID

Basil
Jerome County, Idaho Zone 6b June

Your June gardening checklist

We've pulled the most time-sensitive tasks for Jerome County, Idaho this June and put them front and centre. Tackle them in order.

Avg. last frost May 10
Avg. first frost October 4
Soil temp (4") 55°F
Watering Critical
Pest pressure High
Daylight 15.1 hrs
  1. Begin indoor sowing: basil

    You're about 16 weeks out from your last frost — the perfect window to get these germinating indoors.

Before July arrives, get these ready
  • First harvests: 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.

Jerome County, Idaho is in USDA Zone 6b. The average last spring frost is May 10 and the first fall frost is October 4, giving you a growing season of approximately 147 days.

At an elevation of 6,306 feet, Jerome County receives approximately 13.5 inches of rainfall annually with predominantly loam soil. Summer highs average 85°F, providing good warmth for Basil during the growing season. With low rainfall, drip irrigation is essential for growing Basil successfully. Mulch heavily to conserve soil moisture.

Jerome County, ID (Zone 6b) Short season
147 days
Last Spring Frost May 10
147 growing days
First Fall Frost October 4

Jerome County Soil Profile

Soil Type

Loam

Soil pH

6.8-7.9

Drainage

Well Drained

Basil Planting Risk Windows

Early Start (70% safe) ✓ Fits season (17 days to spare)
Start indoors: Mar 13 Transplant: May 15 🍅 Harvest: Jul 10 – Sep 11
Recommended (50%) ✓ Fits season (14 days to spare)
Start indoors: Mar 22 Transplant: May 24 🍅 Harvest: Jul 19 – Sep 20
Safe Start (90%) ✓ Fits season (7 days to spare)
Start indoors: Apr 16 Transplant: Jun 18 🍅 Harvest: Aug 13 – Oct 15

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 Jerome County

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

Soil pH

Your soil pH (6.8–7.9) is more alkaline than Basil prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.8%). Annual compost additions will help Basil.

How to Plant Basil

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

Succession Planting Basil

3
successive plantings in your 147-day season

Sow every 5.7 weeks. Last sowing by Jul 21 to harvest before frost.

Basil Water Budget

Plant needs
0.6″/week
Rainfall provides
0.4″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 336 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — 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" 0" ❄️ Dormant
Feb 0.8" 0" ❄️ Dormant
Mar 1.3" 0" ❄️ Dormant
Apr 1.6" 0" ❄️ Dormant
May 2.6" 1.5" 1.1" 💧 Light watering
Jun 2.6" 1" 1.6" 🚿 Regular watering
Jul 2.6" 1.2" 1.4" 🚿 Regular watering
Aug 2.6" 1.3" 1.3" 🚿 Regular watering
Sep 2.6" 1.1" 1.5" 🚿 Regular watering
Oct 2.6" 1.1" 1.5" 🚿 Regular watering
Nov 0.8" 0" ❄️ Dormant
Dec 0.8" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Jerome 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 ~859 GDD — county provides 2,021 GDD Excellent fit

Basil Planting Timeline — Jerome County, ID

Basil Planting Calendar

Activity When Date Range
Start Indoors March 22 Mar 22 – Apr 5
Transplant Outdoors May 24 May 24 – Jun 7
Direct Sow May 17 May 17 – Jun 7
Harvest July 19 Jul 19 – Sep 20

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.6"/week · Only during dry spells

📅 Days to Maturity

50–75 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 6b

📆 Growing Season

147 days in Jerome County

Growing Tips for Basil in Jerome County

Direct sow Basil outdoors after May 10 in Jerome 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 Jerome County, ID?

Jerome County is in Zone 6b with an average last frost of May 10. Plan your Basil planting based on this frost date — see the calendar above for exact timing.

What planting zone is Jerome County, ID?

Jerome County, Idaho is in USDA Hardiness Zone 6b. The average last spring frost is May 10 and first fall frost is October 4.

When should I plant Basil in Jerome County, ?

In Jerome County, , plant Basil after the last frost (around May 10) and before the first frost (around October 4). Best results when soil holds above 50°F.

What growing zone is Jerome County, for Basil?

Jerome County sits in USDA Zone 6b. Basil grows reliably in zones 4a through 11b, so it's a good fit here.

Can Basil grow in Jerome County's climate?

Yes — Basil grows well in Jerome County's temperate climate. Jerome County averages a 147-day frost-free season, with last frost around May 10 and first frost around October 4.

🌱

Your Jerome County Garden Planner — Free

A 22-page printable planner built for Jerome County (Zone 6b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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

Sources & credits

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