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When to Plant Hyssop in Harnett County, NC

Harnett County, North Carolina Zone 7b April

Your April game plan for Harnett County, North Carolina

April rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Harnett County, North Carolina.

Avg. last frost March 29
Avg. first frost November 6
Soil temp (4") 59°F
Watering Low
Pest pressure Moderate
Daylight 12.9 hrs
  1. Get hyssop in the ground

    Your last frost (March 29) has passed. These warm-season crops can handle outdoor soil now.

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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.

Harnett County, North Carolina is in USDA Zone 7b. The average last spring frost is March 29 and the first fall frost is November 6, giving you a growing season of approximately 222 days.

At an elevation of 613 feet, Harnett County receives approximately 53.4 inches of rainfall annually with predominantly clay loam soil. Summer highs average 88°F, providing good warmth for Hyssop during the growing season. Clay soil retains moisture well for Hyssop, but amend with compost to improve drainage and prevent root rot. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Hyssop root diseases.

Harnett County, NC (Zone 7b) Long season
222 days
Last Spring Frost March 29
222 growing days
First Fall Frost November 6

Harnett County Soil Profile

Soil Type

Clay Loam

Soil pH

5.5-6.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (83 days to spare)
Transplant: Mar 30 🍅 Harvest: Jun 8 – Aug 10
Recommended (50%) ✓ Fits season (82 days to spare)
Transplant: Apr 5 🍅 Harvest: Jun 14 – Aug 16
Safe Start (90%) ✓ Fits season (74 days to spare)
Transplant: Apr 24 🍅 Harvest: Jul 3 – Sep 4

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 Harnett County

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

Soil pH

Your soil pH (5.5–6.6) overlaps with Hyssop's range (6.0–8.0), though not a perfect match.

Soil Texture

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

Drainage

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

Organic Matter

Organic matter is moderate (2.8%). Annual compost additions will help Hyssop.

How to Plant Hyssop

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

Succession Planting Hyssop

3
successive plantings in your 222-day season

Sow every 8 weeks. Last sowing by Aug 08 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 4.6" 0" ❄️ Dormant
Feb 3.9" 0" ❄️ Dormant
Mar 2.2" 5" 0" ✅ Rainfall sufficient
Apr 2.2" 4.6" 0" ✅ Rainfall sufficient
May 2.2" 4.5" 0" ✅ Rainfall sufficient
Jun 2.2" 4.3" 0" ✅ Rainfall sufficient
Jul 2.2" 5" 0" ✅ Rainfall sufficient
Aug 2.2" 4.8" 0" ✅ Rainfall sufficient
Sep 2.2" 4.1" 0" ✅ Rainfall sufficient
Oct 2.2" 3.8" 0" ✅ Rainfall sufficient
Nov 2.2" 4.4" 0" ✅ Rainfall sufficient
Dec 4.4" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Harnett 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 ~1,280 GDD — county provides 3,552 GDD Excellent fit

Hyssop Planting Timeline — Harnett County, NC

Hyssop Planting Calendar

Activity When Date Range
Transplant Outdoors April 5 Apr 5 – Apr 19
Harvest June 14 Jun 14 – Aug 16

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

Month-by-Month Timeline

MonthActivities
January
February
March
April Transplant Outdoors
May
June Harvest
July Harvest
August Harvest
September
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: acceptable

🗺️ USDA Zone

Zone 7b

📆 Growing Season

222 days in Harnett County

Growing Tips for Hyssop in Harnett County

Direct sow Hyssop outdoors after March 29 in Harnett County when soil has warmed and frost danger has passed.

With Harnett County's clay soil (27% clay), work in 3-4 inches of compost before planting Hyssop. Avoid tilling when soil is wet to prevent compaction.

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 Harnett County, NC?

Harnett County is in Zone 7b with an average last frost of March 29. Plan your Hyssop planting based on this frost date — see the calendar above for exact timing.

What planting zone is Harnett County, NC?

Harnett County, North Carolina is in USDA Hardiness Zone 7b. The average last spring frost is March 29 and first fall frost is November 6.

🌱

Your Harnett County Garden Planner — Free

A 24-page printable planner built for Harnett 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 Harnett County, NC. Local conditions may vary. Last updated: April 2026.

Sources & credits

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