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When to Plant Hyssop in Duval County, TX

Duval County, Texas Zone 9b May

Duval County, Texas gardeners: here's your May plan

Your Duval County, Texas garden is entering a new phase. Here's what's on the schedule for May and why each task matters now.

Avg. last frost February 13
Avg. first frost December 9
Soil temp (4") 67°F
Watering Low
Pest pressure High
Daylight 13.4 hrs
  1. Harvest hyssop as they ripen

    Morning harvests are best — cooler temperatures mean crisper produce and longer fridge life.

A few tasks this May that'll pay off in June
  • First harvests: hyssop

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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.

Duval County, Texas is in USDA Zone 9b. The average last spring frost is February 13 and the first fall frost is December 9, giving you a growing season of approximately 299 days.

At an elevation of 4,259 feet, Duval County receives approximately 55.2 inches of rainfall annually with predominantly loam soil. Summer highs average 102°F, so Hyssop may need afternoon shade and extra watering during peak heat. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Hyssop root diseases.

Duval County, TX (Zone 9b) Year-round
299 days
Last Spring Frost February 13
299 growing days
First Fall Frost December 9
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Duval County Soil Profile

Soil Type

Loam

Soil pH

6.8-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (174 days to spare)
Transplant: Jan 27 🍅 Harvest: Apr 7 – Jun 9
Recommended (50%) ✓ Fits season (159 days to spare)
Transplant: Feb 20 🍅 Harvest: May 1 – Jul 3
Safe Start (90%) ✓ Fits season (147 days to spare)
Transplant: Mar 15 🍅 Harvest: May 24 – Jul 26

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 Duval County

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

Soil pH

Your soil pH (6.8–7.3) is within Hyssop's preferred range (6.0–8.0).

Soil Texture

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

Organic Matter

Organic matter is moderate (2.1%). Annual compost additions will help Hyssop.

How to Plant Hyssop

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

Succession Planting Hyssop

5
successive plantings in your 299-day season

Sow every 8 weeks. Last sowing by Sep 10 to harvest before frost.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
0.8″/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 2.2" 1.7" 0.5" 💧 Light watering
Mar 2.2" 4" 0" ✅ Rainfall sufficient
Apr 2.2" 5.3" 0" ✅ Rainfall sufficient
May 2.2" 8.7" 0" ✅ Rainfall sufficient
Jun 2.2" 8.4" 0" ✅ Rainfall sufficient
Jul 2.2" 6.8" 0" ✅ Rainfall sufficient
Aug 2.2" 6" 0" ✅ Rainfall sufficient
Sep 2.2" 5.7" 0" ✅ Rainfall sufficient
Oct 2.2" 3.6" 0" ✅ Rainfall sufficient
Nov 2.2" 1.9" 0.3" 💧 Light watering
Dec 2.2" 1.6" 0.6" 💧 Light watering

Water needs are for active growing months only (Feb–Dec in Duval 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 ~2,120 GDD — county provides 7,950 GDD Excellent fit

Hyssop Planting Timeline — Duval County, TX

Hyssop Planting Calendar

Activity When Date Range
Transplant Outdoors February 20 Feb 20 – Mar 6
Harvest May 1 May 1 – Jul 3

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

Month-by-Month Timeline

MonthActivities
January
February Transplant Outdoors
March Transplant Outdoors
April
May Harvest
June Harvest
July Harvest
August
September
October
November
December
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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 9b

📆 Growing Season

299 days in Duval County

Growing Tips for Hyssop in Duval County

Direct sow Hyssop outdoors after February 13 in Duval County when soil has warmed and frost danger has passed.

With summer highs reaching 102°F in Duval County, provide afternoon shade for Hyssop and water deeply in the morning.

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 Duval County, TX?

Duval County is in Zone 9b with an average last frost of February 13. Plan your Hyssop planting based on this frost date — see the calendar above for exact timing.

What planting zone is Duval County, TX?

Duval County, Texas is in USDA Hardiness Zone 9b. The average last spring frost is February 13 and first fall frost is December 9.

🌱

Your Duval County Garden Planner — Free

A 24-page printable planner built for Duval County (Zone 9b). 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 Duval County, TX. 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.