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When to Plant Rosemary in Dukes County, MA

Dukes County, Massachusetts Zone 7b May

Your May planting checklist for Dukes County, Massachusetts

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

Avg. last frost April 25
Avg. first frost October 19
Soil temp (4") 68°F
Watering Low
Pest pressure Moderate
Daylight 14.3 hrs
  1. Move rosemary from tray to bed

    Bring a watering can to the bed. Each transplant gets a drink the moment it's in the ground, not ten minutes later.

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Rosemary is an aromatic evergreen shrub with needle-like leaves and a piney, citrus flavor. It is a Mediterranean herb that thrives in warm, dry conditions.

Dukes County, Massachusetts is in USDA Zone 7b. The average last spring frost is April 25 and the first fall frost is October 19, giving you a growing season of approximately 177 days.

At an elevation of 676 feet, Dukes County receives approximately 48.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88°F, providing good warmth for Rosemary during the growing season.

Dukes County, MA (Zone 7b) Moderate season
177 days
Last Spring Frost April 25
177 growing days
First Fall Frost October 19

Dukes County Soil Profile

Soil Type

Silt Loam

Soil pH

5.2-6.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: Apr 21 🍅 Harvest: Jul 14 – Dec 1
Recommended (50%) ✗ May not fit
Transplant: May 2 🍅 Harvest: Jul 25 – Dec 12
Safe Start (90%) ✗ May not fit
Transplant: May 21 🍅 Harvest: Aug 13 – Dec 31

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 Dukes County

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

Soil pH

Your soil pH (5.2–6.5) is more acidic than Rosemary prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

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

Drainage

Rosemary prefers dry conditions but your soil drains poorly. Use raised beds or mounded rows to prevent root rot.

Organic Matter

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

How to Plant Rosemary

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

Succession Planting Rosemary

2
successive plantings in your 177-day season

Sow every 9.1 weeks. Last sowing by Apr 22 to harvest before frost.

Plant Water Budget

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

Monthly Watering Guide for Rosemary

Rosemary needs approximately 0.3 inches of water per week (1.3" per month). Here's how your county's rainfall compares month by month.

Month Rosemary Needs Rainfall You Supplement Action
Jan 3.7" 0" ❄️ Dormant
Feb 2.8" 0" ❄️ Dormant
Mar 3.4" 0" ❄️ Dormant
Apr 1.3" 4.5" 0" ✅ Rainfall sufficient
May 1.3" 4.5" 0" ✅ Rainfall sufficient
Jun 1.3" 4.2" 0" ✅ Rainfall sufficient
Jul 1.3" 4.8" 0" ✅ Rainfall sufficient
Aug 1.3" 4.8" 0" ✅ Rainfall sufficient
Sep 1.3" 4.4" 0" ✅ Rainfall sufficient
Oct 1.3" 4.1" 0" ✅ Rainfall sufficient
Nov 3.5" 0" ❄️ Dormant
Dec 3.5" 0" ❄️ Dormant

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

Rosemary 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.

Rosemary needs ~2,080 GDD — county provides 2,832 GDD Excellent fit

Rosemary Planting Timeline — Dukes County, MA

Rosemary Planting Calendar

Activity When Date Range
Transplant Outdoors May 2 May 2 – May 16
Harvest July 25 Jul 25 – Dec 12

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.3"/week · Natural rainfall sufficient

📅 Days to Maturity

80–180 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 7b

📆 Growing Season

177 days in Dukes County

Growing Tips for Rosemary in Dukes County

Direct sow Rosemary outdoors after April 25 in Dukes County when soil has warmed and frost danger has passed.

Your 177.0-day growing season in Dukes County is tight for Rosemary (80.0-180.0 days to maturity). Start indoors and choose early-maturing varieties.

General growing tips

Grow in well-drained soil and avoid overwatering. In cold climates, grow in containers and bring indoors for winter. Propagate from stem cuttings for faster results than seed.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Rosemary in Dukes County, MA?

Dukes County is in Zone 7b with an average last frost of April 25. Plan your Rosemary planting based on this frost date — see the calendar above for exact timing.

What planting zone is Dukes County, MA?

Dukes County, Massachusetts is in USDA Hardiness Zone 7b. The average last spring frost is April 25 and first fall frost is October 19.

🌱

Your Dukes County Garden Planner — Free

A 24-page printable planner built for Dukes 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 Dukes 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.