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When to Plant Hyssop in Jackson County, CO

Jackson County, Colorado Zone 4b May

May in Jackson County, Colorado — your action list

A quick May briefing for Jackson County, Colorado gardeners — what's urgent, what's next, and what can wait.

Avg. last frost June 13
Avg. first frost September 4
Soil temp (4") 34°F
Watering High
Pest pressure Low
Daylight 14.3 hrs
Get ahead of June
  • Transplants going out: 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.

Jackson County, Colorado is in USDA Zone 4b. The average last spring frost is June 13 and the first fall frost is September 4, giving you a growing season of approximately 83 days.

At an elevation of 5,388 feet, Jackson County receives approximately 20.9 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Hyssop to ensure they mature before fall.

Jackson County, CO (Zone 4b) Very short season
83 days
Last Spring Frost June 13
83 growing days
First Fall Frost September 4

Jackson County Soil Profile

Soil Type

Loam

Soil pH

6.6-8.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: Jun 15 🍅 Harvest: Aug 24 – Oct 26
Recommended (50%) ✗ May not fit
Transplant: Jun 20 🍅 Harvest: Aug 29 – Oct 31
Safe Start (90%) ✗ May not fit
Transplant: Jul 2 🍅 Harvest: Sep 10 – Nov 12

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 Jackson County

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

Soil pH

Your soil pH (6.6–8.1) overlaps with Hyssop's range (6.0–8.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.2%). Annual compost additions will help Hyssop.

How to Plant Hyssop

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

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
1.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

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 1.1" 0" ❄️ Dormant
Mar 1.9" 0" ❄️ Dormant
Apr 2.3" 0" ❄️ Dormant
May 2.2" 0" ❄️ Dormant
Jun 2.2" 1.7" 0.5" 💧 Light watering
Jul 2.2" 1.7" 0.5" 💧 Light watering
Aug 2.2" 2.5" 0" ✅ Rainfall sufficient
Sep 2.2" 1.5" 0.7" 💧 Light watering
Oct 2.1" 0" ❄️ Dormant
Nov 1.4" 0" ❄️ Dormant
Dec 1.1" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Sep in Jackson 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 ~800 GDD — county provides 830 GDD Good fit

Hyssop Planting Timeline — Jackson County, CO

Hyssop Planting Calendar

Activity When Date Range
Transplant Outdoors June 20 Jun 20 – Jul 4
Harvest August 29 Aug 29 – Oct 31

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

Month-by-Month Timeline

MonthActivities
January
February
March
April
May
June Transplant Outdoors
July Transplant Outdoors
August Harvest
September Harvest
October Harvest
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 4b

📆 Growing Season

83 days in Jackson County

Growing Tips for Hyssop in Jackson County

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

Your 83.0-day growing season in Jackson County is tight for Hyssop (70.0-90.0 days to maturity). Start indoors and choose early-maturing varieties.

Jackson County receives only 21" of rain annually. Hyssop needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

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 Jackson County, CO?

Jackson County is in Zone 4b with an average last frost of June 13. Plan your Hyssop planting based on this frost date — see the calendar above for exact timing.

What planting zone is Jackson County, CO?

Jackson County, Colorado is in USDA Hardiness Zone 4b. The average last spring frost is June 13 and first fall frost is September 4.

🌱

Your Jackson County Garden Planner — Free

A 24-page printable planner built for Jackson County (Zone 4b). 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 Jackson County, CO. Local conditions may vary. Last updated: May 2026.

Sources & credits

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