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When to Plant Thai Basil in Nantucket County, MA

Nantucket County, Massachusetts Zone 7b May

Your May planting checklist for Nantucket County, Massachusetts

We've pulled the most time-sensitive tasks for Nantucket County, Massachusetts this May and put them front and centre. Tackle them in order.

Avg. last frost April 12
Avg. first frost November 4
Soil temp (4") 69°F
Watering Low
Pest pressure Moderate
Daylight 14.3 hrs
  1. Start thai basil under lights

    Starting these indoors now means sturdy transplants ready the moment your soil warms up.

June prep starts now
  • First harvests: thai basil

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Thai basil has a distinctive anise-licorice flavor with sturdy purple stems and small leaves. It is essential in Thai, Vietnamese, and other Southeast Asian cuisines.

Nantucket County, Massachusetts is in USDA Zone 7b. The average last spring frost is April 12 and the first fall frost is November 4, giving you a growing season of approximately 206 days.

At an elevation of 632 feet, Nantucket County receives approximately 48 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88°F, providing good warmth for Thai Basil during the growing season.

Nantucket County, MA (Zone 7b) Long season
206 days
Last Spring Frost April 12
206 growing days
First Fall Frost November 4
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Nantucket County Soil Profile

Soil Type

Silt Loam

Soil pH

4.9-6.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (70 days to spare)
Start indoors: Feb 19 Transplant: Apr 23 🍅 Harvest: Jun 18 – Aug 20
Recommended (50%) ✓ Fits season (73 days to spare)
Start indoors: Feb 22 Transplant: Apr 26 🍅 Harvest: Jun 21 – Aug 23
Safe Start (90%) ✓ Fits season (65 days to spare)
Start indoors: Mar 15 Transplant: May 17 🍅 Harvest: Jul 12 – Sep 13

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 Nantucket County

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

Soil pH

Your soil pH (4.9–6.2) is more acidic than Thai Basil prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.6%). Annual compost additions will help Thai Basil.

How to Plant Thai Basil

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

Succession Planting Thai Basil

4
successive plantings in your 206-day season

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

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 39 gal / 100 sq ft

Monthly Watering Guide for Thai Basil

Thai Basil needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Thai Basil Needs Rainfall You Supplement Action
Jan 3.3" 0" ❄️ Dormant
Feb 3.3" 0" ❄️ Dormant
Mar 4.4" 0" ❄️ Dormant
Apr 4.3" 3.9" 0.4" 💧 Light watering
May 4.3" 4.9" 0" ✅ Rainfall sufficient
Jun 4.3" 4.4" 0" ✅ Rainfall sufficient
Jul 4.3" 4.9" 0" ✅ Rainfall sufficient
Aug 4.3" 4.2" 0.1" 💧 Light watering
Sep 4.3" 4.1" 0.2" 💧 Light watering
Oct 4.3" 3.7" 0.6" 💧 Light watering
Nov 4.3" 3.7" 0.6" 💧 Light watering
Dec 3.3" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Nov in Nantucket County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Thai 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.

Thai Basil needs ~1,000 GDD — county provides 3,296 GDD Excellent fit

Thai Basil Planting Timeline — Nantucket County, MA

Thai Basil Planting Calendar

Activity When Date Range
Start Indoors February 22 Feb 22 – Mar 8
Transplant Outdoors April 26 Apr 26 – May 10
Direct Sow April 19 Apr 19 – May 10
Harvest June 21 Jun 21 – Aug 23

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

50–75 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 7b

📆 Growing Season

206 days in Nantucket County

Growing Tips for Thai Basil in Nantucket County

Direct sow Thai Basil outdoors after April 12 in Nantucket County when soil has warmed and frost danger has passed.

General growing tips

Start seeds indoors or direct sow after last frost. Thai basil holds up better to heat in cooking than sweet basil. Pinch flowers to prolong leaf production.

Companion Planting

Good Companions

Avoid Planting Near

  • Rue
  • Sage

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Thai Basil in Nantucket County, MA?

Nantucket County is in Zone 7b with an average last frost of April 12. Plan your Thai Basil planting based on this frost date — see the calendar above for exact timing.

What planting zone is Nantucket County, MA?

Nantucket County, Massachusetts is in USDA Hardiness Zone 7b. The average last spring frost is April 12 and first fall frost is November 4.

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Your Nantucket County Garden Planner — Free

A 24-page printable planner built for Nantucket County (Zone 7b). 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 Nantucket County, MA. 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.