When to Plant Hyssop in Fremont County, ID
Top priorities for Fremont County, Idaho gardeners in April
A quick April briefing for Fremont County, Idaho gardeners — what's urgent, what's next, and what can wait.
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.
Fremont County, Idaho is in USDA Zone 4b. The average last spring frost is June 12 and the first fall frost is September 6, giving you a growing season of approximately 86 days.
At an elevation of 5,282 feet, Fremont County receives approximately 12.7 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Hyssop to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Hyssop successfully. Mulch heavily to conserve soil moisture.
Fremont County Soil Profile
Soil Type
Loam
Soil pH
6.4-8
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 Fremont County
How your county's soil matches Hyssop's growing requirements.
Soil pH
Your soil pH (6.4–8.0) is within Hyssop's preferred range (6.0–8.0).
Soil Texture
The loam soil in Fremont County is excellent for Hyssop — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.6%). Annual compost additions will help Hyssop.
How to Plant Hyssop
Plant Water Budget
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 | — | 0.8" | 0" | ❄️ Dormant |
| Feb | — | 0.8" | 0" | ❄️ Dormant |
| Mar | — | 1.2" | 0" | ❄️ Dormant |
| Apr | — | 1.2" | 0" | ❄️ Dormant |
| May | — | 1.6" | 0" | ❄️ Dormant |
| Jun | 2.2" | 1" | 1.2" | 🚿 Regular watering |
| Jul | 2.2" | 1" | 1.2" | 🚿 Regular watering |
| Aug | 2.2" | 1.5" | 0.7" | 💧 Light watering |
| Sep | 2.2" | 1" | 1.2" | 🚿 Regular watering |
| Oct | — | 1" | 0" | ❄️ Dormant |
| Nov | — | 0.9" | 0" | ❄️ Dormant |
| Dec | — | 0.7" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Jun–Sep in Fremont 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 — Fremont County, ID
Hyssop Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | June 19 | Jun 19 – Jul 3 |
| Harvest | August 28 | Aug 28 – Oct 30 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| 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: ideal
🗺️ USDA Zone
Zone 4b
📆 Growing Season
86 days in Fremont County
Growing Tips for Hyssop in Fremont County
Direct sow Hyssop outdoors after June 12 in Fremont County when soil has warmed and frost danger has passed.
Your 86.0-day growing season in Fremont County is tight for Hyssop (70.0-90.0 days to maturity). Start indoors and choose early-maturing varieties.
Fremont County receives only 13" 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
Check more plant combinations with our Companion Planting Checker →
Hyssop in Other Locations
Frequently Asked Questions
When should I plant Hyssop in Fremont County, ID?
Fremont County is in Zone 4b with an average last frost of June 12. Plan your Hyssop planting based on this frost date — see the calendar above for exact timing.
What planting zone is Fremont County, ID?
Fremont County, Idaho is in USDA Hardiness Zone 4b. The average last spring frost is June 12 and first fall frost is September 6.
Your Fremont County Garden Planner — Free
A 24-page printable planner built for Fremont 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.