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When to Plant Sunchoke in Plymouth County, MA

Plymouth County, Massachusetts Zone 6b May

Top priorities for Plymouth County, Massachusetts gardeners in May

If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.

Avg. last frost April 18
Avg. first frost October 26
Soil temp (4") 64°F
Watering Low
Pest pressure Low
Daylight 14.4 hrs
  1. Get sunchoke in the ground

    Pick a cloudy afternoon or evening to plant. Less transplant shock, and your seedlings will barely blink.

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Sunchokes (Jerusalem artichokes) are a native sunflower relative grown for their knobby, nutty-flavored tubers. They are extremely productive and nearly impossible to eradicate.

Plymouth County, Massachusetts is in USDA Zone 6b. The average last spring frost is April 18 and the first fall frost is October 26, giving you a growing season of approximately 191 days.

At an elevation of 947 feet, Plymouth County receives approximately 46.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Sunchoke during the growing season.

Plymouth County, MA (Zone 6b) Moderate season
191 days
Last Spring Frost April 18
191 growing days
First Fall Frost October 26
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Plymouth County Soil Profile

Soil Type

Silt Loam

Soil pH

4.8-6.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (7 days to spare)
Transplant: Apr 26 🍅 Harvest: Aug 16 – Oct 11
Recommended (50%) ✓ Fits season (9 days to spare)
Transplant: May 2 🍅 Harvest: Aug 22 – Oct 17
Safe Start (90%) ✓ Fits season (8 days to spare)
Transplant: May 12 🍅 Harvest: Sep 1 – Oct 27

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 Plymouth County

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

Soil pH

Your soil pH (4.8–6.6) is more acidic than Sunchoke prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

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

How to Plant Sunchoke

1"
Planting Depth
30"
Between Plants
42"
Between Rows

Plant Water Budget

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

Monthly Watering Guide for Sunchoke

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

Month Sunchoke Needs Rainfall You Supplement Action
Jan 3" 0" ❄️ Dormant
Feb 2.6" 0" ❄️ Dormant
Mar 3.7" 0" ❄️ Dormant
Apr 4.3" 4.3" 0" ✅ Rainfall sufficient
May 4.3" 4.6" 0" ✅ Rainfall sufficient
Jun 4.3" 4.5" 0" ✅ Rainfall sufficient
Jul 4.3" 5.2" 0" ✅ Rainfall sufficient
Aug 4.3" 4.1" 0.2" 💧 Light watering
Sep 4.3" 3.3" 1" 💧 Light watering
Oct 4.3" 3.3" 1" 💧 Light watering
Nov 3.9" 0" ❄️ Dormant
Dec 3.6" 0" ❄️ Dormant

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

Sunchoke 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.

Sunchoke needs ~2,275 GDD — county provides 3,342 GDD Excellent fit

Sunchoke Planting Timeline — Plymouth County, MA

Sunchoke Planting Calendar

Activity When Date Range
Transplant Outdoors May 2 May 2 – May 16
Harvest August 22 Aug 22 – Oct 17

Plant 1" deep · 30" apart · Rows 42" apart

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

110–150 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 6b

📆 Growing Season

191 days in Plymouth County

Growing Tips for Sunchoke in Plymouth County

Direct sow Sunchoke outdoors after April 18 in Plymouth County when soil has warmed and frost danger has passed.

Common pests for Sunchoke in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.

General growing tips

Plant tubers 4 inches deep in early spring. Contain plants with barriers as they spread aggressively. Harvest after frost or leave in ground and dig as needed through winter.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Sunchoke in Plymouth County, MA?

Plymouth County is in Zone 6b with an average last frost of April 18. Plan your Sunchoke planting based on this frost date — see the calendar above for exact timing.

What planting zone is Plymouth County, MA?

Plymouth County, Massachusetts is in USDA Hardiness Zone 6b. The average last spring frost is April 18 and first fall frost is October 26.

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Your Plymouth County Garden Planner — Free

A 24-page printable planner built for Plymouth 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 Plymouth 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.