When to Plant Hyssop in Dallas County, TX
Your May game plan for Dallas County, Texas
A quick May briefing for Dallas County, Texas gardeners — what's urgent, what's next, and what can wait.
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Pick hyssop
Check every 1–2 days. Many of these get tough or go to seed if you wait too long.
Looking ahead to June
- First harvests: hyssop
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.
Dallas County, Texas is in USDA Zone 8b. The average last spring frost is March 8 and the first fall frost is November 20, giving you a growing season of approximately 257 days.
At an elevation of 67 feet, Dallas County receives approximately 65.7 inches of rainfall annually with predominantly clay soil. Summer highs average 97°F, so Hyssop may need afternoon shade and extra watering during peak heat. 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.
Dallas County Soil Profile
Soil Type
Clay
Soil pH
6.7-8.4
Drainage
Well Drained
Plant Planting Risk Windows
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 Dallas County
How your county's soil matches Hyssop's growing requirements.
Soil pH
Your soil pH (6.7–8.4) overlaps with Hyssop's range (6.0–8.0), though not a perfect match.
Soil Texture
Heavy clay soil (48% clay) in Dallas County compacts easily and drains slowly. Amend with compost and avoid working soil when wet.
Organic Matter
Organic matter is moderate (2.6%). Annual compost additions will help Hyssop.
How to Plant Hyssop
Succession Planting Hyssop
Sow every 8 weeks. Last sowing by Aug 22 to harvest before frost.
Plant Water Budget
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 | — | 1.5" | 0" | ❄️ Dormant |
| Feb | — | 2.5" | 0" | ❄️ Dormant |
| Mar | 2.2" | 4.4" | 0" | ✅ Rainfall sufficient |
| Apr | 2.2" | 7.1" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 9.2" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 10.4" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 7.4" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 8.3" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 6" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 4.6" | 0" | ✅ Rainfall sufficient |
| Nov | 2.2" | 2.4" | 0" | ✅ Rainfall sufficient |
| Dec | — | 1.7" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Mar–Nov in Dallas 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 Planting Timeline — Dallas County, TX
Hyssop Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | March 15 | Mar 15 – Mar 29 |
| Harvest | May 24 | May 24 – Jul 26 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Transplant Outdoors |
| April | — |
| May | Harvest |
| June | Harvest |
| July | Harvest |
| August | — |
| 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 8b
📆 Growing Season
257 days in Dallas County
Growing Tips for Hyssop in Dallas County
Direct sow Hyssop outdoors after March 08 in Dallas County when soil has warmed and frost danger has passed.
With Dallas County's clay soil (48% clay), work in 3-4 inches of compost before planting Hyssop. Avoid tilling when soil is wet to prevent compaction.
With summer highs reaching 97°F in Dallas 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
Check more plant combinations with our Companion Planting Checker →
Hyssop in Other Locations
Frequently Asked Questions
When should I plant Hyssop in Dallas County, TX?
Dallas County is in Zone 8b with an average last frost of March 8. Plan your Hyssop planting based on this frost date — see the calendar above for exact timing.
What planting zone is Dallas County, TX?
Dallas County, Texas is in USDA Hardiness Zone 8b. The average last spring frost is March 8 and first fall frost is November 20.
Your Dallas County Garden Planner — Free
A 24-page printable planner built for Dallas County (Zone 8b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.