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When to Plant Hyssop in Branch County, MI

Branch County, Michigan Zone 6a May

What to do 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 28
Avg. first frost October 14
Soil temp (4") 56°F
Watering Low
Pest pressure Low
Daylight 14.4 hrs
  1. Move hyssop into the garden

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

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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.

Branch County, Michigan is in USDA Zone 6a. The average last spring frost is April 28 and the first fall frost is October 14, giving you a growing season of approximately 169 days.

At an elevation of 900 feet, Branch County receives approximately 39.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Hyssop to ensure they mature before fall.

Branch County, MI (Zone 6a) Moderate season
169 days
Last Spring Frost April 28
169 growing days
First Fall Frost October 14

Branch County Soil Profile

Soil Type

Silt Loam

Soil pH

6-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (25 days to spare)
Transplant: May 2 🍅 Harvest: Jul 11 – Sep 12
Recommended (50%) ✓ Fits season (29 days to spare)
Transplant: May 5 🍅 Harvest: Jul 14 – Sep 15
Safe Start (90%) ✓ Fits season (23 days to spare)
Transplant: May 22 🍅 Harvest: Jul 31 – Oct 2

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 Branch County

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

Soil pH

Your soil pH (6.0–6.9) is within Hyssop's preferred range (6.0–8.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.5%) — 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 169-day season

Sow every 8 weeks. Last sowing by Jul 16 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 1.6" 0" ❄️ Dormant
Feb 1.8" 0" ❄️ Dormant
Mar 3" 0" ❄️ Dormant
Apr 2.2" 3.4" 0" ✅ Rainfall sufficient
May 2.2" 3.8" 0" ✅ Rainfall sufficient
Jun 2.2" 5.1" 0" ✅ Rainfall sufficient
Jul 2.2" 4.6" 0" ✅ Rainfall sufficient
Aug 2.2" 4.5" 0" ✅ Rainfall sufficient
Sep 2.2" 3.8" 0" ✅ Rainfall sufficient
Oct 2.2" 3.3" 0" ✅ Rainfall sufficient
Nov 2.5" 0" ❄️ Dormant
Dec 2.2" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Branch 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 ~1,040 GDD — county provides 2,197 GDD Excellent fit

Hyssop Planting Timeline — Branch County, MI

Hyssop Planting Calendar

Activity When Date Range
Transplant Outdoors May 5 May 5 – May 19
Harvest July 14 Jul 14 – Sep 15

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
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 6a

📆 Growing Season

169 days in Branch County

Growing Tips for Hyssop in Branch County

Direct sow Hyssop outdoors after April 28 in Branch 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 Branch County, MI?

Branch County is in Zone 6a with an average last frost of April 28. Plan your Hyssop planting based on this frost date — see the calendar above for exact timing.

What planting zone is Branch County, MI?

Branch County, Michigan is in USDA Hardiness Zone 6a. The average last spring frost is April 28 and first fall frost is October 14.

🌱

Your Branch County Garden Planner — Free

A 24-page printable planner built for Branch County (Zone 6a). 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 Branch County, MI. 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.