Blog

When to plant Basil in Aroostook County, ME

In Aroostook County, Basil is a single-season spring crop — there's no second fall window. Plant May 25–June 15 for an 75-day harvest, finishing well before the September 24 first frost.

When to Plant Basil in Aroostook County, ME

Basil
Aroostook County, Maine Zone 4a June

June in the garden — Aroostook County, Maine

A quick June briefing for Aroostook County, Maine gardeners — what's urgent, what's next, and what can wait.

Avg. last frost May 18
Avg. first frost September 24
Soil temp (4") 61°F
Watering Moderate
Pest pressure Moderate
Daylight 15.6 hrs
  1. Move basil from tray to bed

    Water the tray well an hour before you transplant. Roots slide out cleanly and settle in faster.

July will be here before you know it — start on
  • Starting indoors: basil

Instant PDF download. No spam, unsubscribe any time.

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.

Aroostook County, Maine is in USDA Zone 4a. The average last spring frost is May 18 and the first fall frost is September 24, giving you a growing season of approximately 129 days.

At an elevation of 314 feet, Aroostook County receives approximately 39.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 78°F, so choose short-season varieties of Basil to ensure they mature before fall.

Aroostook County, ME (Zone 4a) Short season
129 days
Last Spring Frost May 18
129 growing days
First Fall Frost September 24

Aroostook County Soil Profile

Soil Type

Silt Loam

Soil pH

4.9-6.3

Drainage

Well Drained

Basil Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 17 Transplant: Jun 2 🍅 Harvest: Jul 28 – Sep 29
Recommended (50%) ✗ May not fit
Start indoors: Mar 23 Transplant: Jun 8 🍅 Harvest: Aug 3 – Oct 5
Safe Start (90%) ✗ May not fit
Start indoors: Apr 6 Transplant: Jun 22 🍅 Harvest: Aug 17 – Oct 19

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 Aroostook County

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

Soil pH

Your soil pH (4.9–6.3) is more acidic than Basil prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.8%). Annual compost additions will help Basil.

How to Plant Basil

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

Succession Planting Basil

2
successive plantings in your 129-day season

Sow every 5.7 weeks. Last sowing by Jul 11 to harvest before frost.

Basil Water Budget

Plant needs
0.6″/week
Rainfall provides
1.3″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

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 2.8" 0" ❄️ Dormant
Feb 2.7" 0" ❄️ Dormant
Mar 3.3" 0" ❄️ Dormant
Apr 3.5" 0" ❄️ Dormant
May 2.6" 3.3" 0" ✅ Rainfall sufficient
Jun 2.6" 3.7" 0" ✅ Rainfall sufficient
Jul 2.6" 3.6" 0" ✅ Rainfall sufficient
Aug 2.6" 3.6" 0" ✅ Rainfall sufficient
Sep 2.6" 3.9" 0" ✅ Rainfall sufficient
Oct 3.2" 0" ❄️ Dormant
Nov 2.9" 0" ❄️ Dormant
Dec 3" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Aroostook 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 ~531 GDD — county provides 1,096 GDD Excellent fit

Basil Planting Timeline — Aroostook County, ME

Basil Planting Calendar

Activity When Date Range
Start Indoors March 23 Mar 23 – Apr 6
Transplant Outdoors June 8 Jun 8 – Jun 22
Direct Sow May 25 May 25 – Jun 15
Harvest August 3 Aug 3 – Oct 5

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

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April Start Indoors
May Direct Sow
June Transplant Outdoors Direct Sow
July
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_acidic

🗺️ USDA Zone

Zone 4a

📆 Growing Season

129 days in Aroostook County

Growing Tips for Basil in Aroostook County

Direct sow Basil outdoors after May 18 in Aroostook 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 Aroostook County, ME?

Aroostook County is in Zone 4a with an average last frost of May 18. Plan your Basil planting based on this frost date — see the calendar above for exact timing.

What planting zone is Aroostook County, ME?

Aroostook County, Maine is in USDA Hardiness Zone 4a. The average last spring frost is May 18 and first fall frost is September 24.

When should I plant Basil in Aroostook County, ME?

In Aroostook County, ME, plant Basil after the last frost (around May 18) and before the first frost (around September 24). Best results when soil holds above 50°F.

What growing zone is Aroostook County, ME for Basil?

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

Can Basil grow in Aroostook County's climate?

Yes — Basil grows well in Aroostook County's temperate climate. Aroostook County averages a 129-day frost-free season, with last frost around May 18 and first frost around September 24.

🌱

Your Aroostook County Garden Planner — Free

A 22-page printable planner built for Aroostook County (Zone 4a). 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 Aroostook County, ME. 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.