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When to Plant Hyssop in Vermilion Parish, LA

Vermilion Parish, Louisiana Zone 9a May

What to do in May

Your garden in Vermilion Parish, Louisiana is working on a schedule, even when you're not. Here's where you should be this May.

Avg. last frost February 13
Avg. first frost December 5
Soil temp (4") 76°F
Watering Low
Pest pressure High
Daylight 13.5 hrs
  1. Basket week: hyssop

    Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.

Coming up in June — start thinking about
  • 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.

Vermilion Parish, Louisiana is in USDA Zone 9a. The average last spring frost is February 13 and the first fall frost is December 5, giving you a growing season of approximately 295 days.

At an elevation of 430 feet, Vermilion Parish receives approximately 54.1 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 99°F, so Hyssop may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Hyssop will need more frequent watering and organic matter to retain nutrients. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Hyssop root diseases.

Vermilion Parish, LA (Zone 9a) Year-round
295 days
Last Spring Frost February 13
295 growing days
First Fall Frost December 5
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Vermilion Parish Soil Profile

Soil Type

Sandy Loam

Soil pH

5-6.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (159 days to spare)
Transplant: Feb 7 🍅 Harvest: Apr 18 – Jun 20
Recommended (50%) ✓ Fits season (155 days to spare)
Transplant: Feb 20 🍅 Harvest: May 1 – Jul 3
Safe Start (90%) ✓ Fits season (145 days to spare)
Transplant: Mar 16 🍅 Harvest: May 25 – Jul 27

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 Vermilion Parish

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

Soil pH

Your soil pH (5.0–6.3) is more acidic than Hyssop prefers (6.0–8.0). Add garden lime to raise pH.

Soil Texture

Sandy soil in Vermilion Parish warms quickly in spring but drains fast. Hyssop will need more frequent watering and regular compost additions to retain nutrients.

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 low (1.7%). Add 2-3 inches of compost before planting Hyssop.

How to Plant Hyssop

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

Succession Planting Hyssop

5
successive plantings in your 295-day season

Sow every 8 weeks. Last sowing by Sep 06 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 4.7" 0" ❄️ Dormant
Feb 2.2" 4.2" 0" ✅ Rainfall sufficient
Mar 2.2" 5.8" 0" ✅ Rainfall sufficient
Apr 2.2" 4.8" 0" ✅ Rainfall sufficient
May 2.2" 4.2" 0" ✅ Rainfall sufficient
Jun 2.2" 4.5" 0" ✅ Rainfall sufficient
Jul 2.2" 4.9" 0" ✅ Rainfall sufficient
Aug 2.2" 4.5" 0" ✅ Rainfall sufficient
Sep 2.2" 4.5" 0" ✅ Rainfall sufficient
Oct 2.2" 3" 0" ✅ Rainfall sufficient
Nov 2.2" 3.9" 0" ✅ Rainfall sufficient
Dec 2.2" 5" 0" ✅ Rainfall sufficient

Water needs are for active growing months only (Feb–Dec in Vermilion Parish). 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 ~1,940 GDD — county provides 7,178 GDD Excellent fit

Hyssop Planting Timeline — Vermilion Parish, LA

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: too_acidic

🗺️ USDA Zone

Zone 9a

📆 Growing Season

295 days in Vermilion Parish

Growing Tips for Hyssop in Vermilion Parish

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

Sandy soil in Vermilion Parish dries quickly — mulch Hyssop with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

With summer highs reaching 99°F in Vermilion Parish, 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 Vermilion Parish, LA?

Vermilion Parish is in Zone 9a 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 Vermilion Parish, LA?

Vermilion Parish, Louisiana is in USDA Hardiness Zone 9a. The average last spring frost is February 13 and first fall frost is December 5.

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Your Vermilion Parish Garden Planner — Free

A 24-page printable planner built for Vermilion Parish (Zone 9a). 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 Vermilion Parish, LA. Local conditions may vary. Last updated: May 2026.

Sources & credits

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