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When to Plant Hyssop in Burnett County, WI

Burnett County, Wisconsin Zone 4a May

What to do in May

Here's what deserves your attention in Burnett County, Wisconsin this month. Everything below is tailored to Zone 4a and timed around your local frost dates.

Avg. last frost May 15
Avg. first frost September 27
Soil temp (4") 50°F
Watering Moderate
Pest pressure Low
Daylight 14.7 hrs
  1. Transplant hyssop outside

    Pinch off the lowest leaves on each seedling before you plant — it reduces water loss while the roots catch up.

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Hyssop is a semi-evergreen perennial herb with intense blue flower spikes that attract bees and butterflies. It has a minty, slightly bitter flavor used in liqueurs and teas.

Burnett County, Wisconsin is in USDA Zone 4a. The average last spring frost is May 15 and the first fall frost is September 27, giving you a growing season of approximately 135 days.

At an elevation of 574 feet, Burnett County receives approximately 30.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 79°F, so choose short-season varieties of Hyssop to ensure they mature before fall.

Burnett County, WI (Zone 4a) Short season
135 days
Last Spring Frost May 15
135 growing days
First Fall Frost September 27

Burnett County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 16 🍅 Harvest: Jul 25 – Sep 26
Recommended (50%) ✗ May not fit
Transplant: May 22 🍅 Harvest: Jul 31 – Oct 2
Safe Start (90%) ✗ May not fit
Transplant: Jun 6 🍅 Harvest: Aug 15 – Oct 17

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 Burnett County

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

Soil pH

Your soil pH (6.2–7.3) is within Hyssop's preferred range (6.0–8.0).

Soil Texture

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

Drainage

Drainage is adequate for Hyssop.

Organic Matter

Organic matter is excellent (4.6%) — Hyssop will thrive.

How to Plant Hyssop

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

Succession Planting Hyssop

2
successive plantings in your 135-day season

Sow every 8 weeks. Last sowing by Jun 29 to harvest before frost.

Plant Water Budget

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

Monthly Watering Guide for Hyssop

Hyssop 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 Hyssop Needs Rainfall You Supplement Action
Jan 1.4" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 1.8" 0" ❄️ Dormant
Apr 2.6" 0" ❄️ Dormant
May 2.2" 3.6" 0" ✅ Rainfall sufficient
Jun 2.2" 4.2" 0" ✅ Rainfall sufficient
Jul 2.2" 3" 0" ✅ Rainfall sufficient
Aug 2.2" 3.6" 0" ✅ Rainfall sufficient
Sep 2.2" 2.7" 0" ✅ Rainfall sufficient
Oct 2.5" 0" ❄️ Dormant
Nov 2" 0" ❄️ Dormant
Dec 1.7" 0" ❄️ Dormant

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

Hyssop 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.

Hyssop needs ~740 GDD — county provides 1,248 GDD Excellent fit

Hyssop Planting Timeline — Burnett County, WI

Hyssop Planting Calendar

Activity When Date Range
Transplant Outdoors May 22 May 22 – Jun 5
Harvest July 31 Jul 31 – Oct 2

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

70–90 days

🧪 Soil pH

Needs 6–8 · Your soil: ideal

🗺️ USDA Zone

Zone 4a

📆 Growing Season

135 days in Burnett County

Growing Tips for Hyssop in Burnett County

Direct sow Hyssop outdoors after May 15 in Burnett County when soil has warmed and frost danger has passed.

General growing tips

Start seeds indoors or direct sow in spring. Prune back in early spring to encourage bushy growth. Hyssop is drought-tolerant once established and thrives in poor soil.

Companion Planting

Good Companions

Avoid Planting Near

  • Radish

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Hyssop in Burnett County, WI?

Burnett County is in Zone 4a with an average last frost of May 15. Plan your Hyssop planting based on this frost date — see the calendar above for exact timing.

What planting zone is Burnett County, WI?

Burnett County, Wisconsin is in USDA Hardiness Zone 4a. The average last spring frost is May 15 and first fall frost is September 27.

🌱

Your Burnett County Garden Planner — Free

A 24-page printable planner built for Burnett 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 Burnett 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.