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When to Plant Lemon Balm in Jefferson County, WI

Jefferson County, Wisconsin Zone 5b May

May in the garden — Jefferson County, Wisconsin

May is a pivotal month for Jefferson County, Wisconsin gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost April 27
Avg. first frost October 12
Soil temp (4") 60°F
Watering Low
Pest pressure Low
Daylight 14.5 hrs
  1. Time to transplant lemon balm

    Frost risk is low now in Jefferson County, Wisconsin. If you've been covering beds overnight, you can stop.

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Lemon balm is a vigorous perennial herb with bright green, lemon-scented leaves. It makes a refreshing tea and is easy to grow but can spread aggressively.

Jefferson County, Wisconsin is in USDA Zone 5b. The average last spring frost is April 27 and the first fall frost is October 12, giving you a growing season of approximately 168 days.

At an elevation of 613 feet, Jefferson County receives approximately 36.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Lemon Balm during the growing season.

Jefferson County, WI (Zone 5b) Moderate season
168 days
Last Spring Frost April 27
168 growing days
First Fall Frost October 12

Jefferson County Soil Profile

Soil Type

Silt Loam

Soil pH

6.3-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (48 days to spare)
Transplant: Apr 30 🍅 Harvest: Jul 2 – Aug 20
Recommended (50%) ✓ Fits season (49 days to spare)
Transplant: May 4 🍅 Harvest: Jul 6 – Aug 24
Safe Start (90%) ✓ Fits season (47 days to spare)
Transplant: May 20 🍅 Harvest: Jul 22 – Sep 9

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 Jefferson County

How your county's soil matches Lemon Balm's growing requirements.

Soil pH

Your soil pH (6.3–6.7) is within Lemon Balm's preferred range (5.5–7.5).

Soil Texture

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

Drainage

Drainage is adequate for Lemon Balm.

Organic Matter

Organic matter is excellent (4.1%) — Lemon Balm will thrive.

How to Plant Lemon Balm

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

Succession Planting Lemon Balm

3
successive plantings in your 168-day season

Sow every 6.9 weeks. Last sowing by Aug 03 to harvest before frost.

Plant Water Budget

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

Monthly Watering Guide for Lemon Balm

Lemon Balm needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.

Month Lemon Balm Needs Rainfall You Supplement Action
Jan 1.7" 0" ❄️ Dormant
Feb 1.6" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 2.2" 2.9" 0" ✅ Rainfall sufficient
May 2.2" 4.6" 0" ✅ Rainfall sufficient
Jun 2.2" 4.4" 0" ✅ Rainfall sufficient
Jul 2.2" 3.9" 0" ✅ Rainfall sufficient
Aug 2.2" 4.2" 0" ✅ Rainfall sufficient
Sep 2.2" 3.6" 0" ✅ Rainfall sufficient
Oct 2.2" 2.7" 0" ✅ Rainfall sufficient
Nov 2.7" 0" ❄️ Dormant
Dec 2.2" 0" ❄️ Dormant

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

Lemon Balm 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.

Lemon Balm needs ~991 GDD — county provides 2,562 GDD Excellent fit

Lemon Balm Planting Timeline — Jefferson County, WI

Lemon Balm Planting Calendar

Activity When Date Range
Transplant Outdoors May 4 May 4 – May 18
Harvest July 6 Jul 6 – Aug 24

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
October
November
December

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

60–70 days

🧪 Soil pH

Needs 5.5–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 5b

📆 Growing Season

168 days in Jefferson County

Growing Tips for Lemon Balm in Jefferson County

Direct sow Lemon Balm outdoors after April 27 in Jefferson County when soil has warmed and frost danger has passed.

General growing tips

Start from seed, cuttings, or divisions. Contain in pots or use barriers to prevent spreading. Harvest frequently to keep plants bushy and prevent flowering.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Lemon Balm in Jefferson County, WI?

Jefferson County is in Zone 5b with an average last frost of April 27. Plan your Lemon Balm planting based on this frost date — see the calendar above for exact timing.

What planting zone is Jefferson County, WI?

Jefferson County, Wisconsin is in USDA Hardiness Zone 5b. The average last spring frost is April 27 and first fall frost is October 12.

🌱

Your Jefferson County Garden Planner — Free

A 24-page printable planner built for Jefferson County (Zone 5b). 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 Jefferson County, WI. 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.