When to Plant Horehound in Imperial County, CA
Your May game plan for Imperial County, California
Your Imperial County, California garden is entering a new phase. Here's what's on the schedule for May and why each task matters now.
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Pick horehound
Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.
To set up a strong June, finish these tasks
- First harvests: horehound
Horehound is a woolly, drought-tolerant perennial herb traditionally used for cough remedies and candy. It has a distinctive bitter, menthol-like flavor.
Imperial County, California is in USDA Zone 10a. The average last spring frost is January 29 and the first fall frost is December 20, giving you a growing season of approximately 325 days.
At an elevation of 181 feet, Imperial County receives approximately 16.8 inches of rainfall annually with predominantly loam soil. Summer highs average 93°F, providing good warmth for Horehound during the growing season. With low rainfall, drip irrigation is essential for growing Horehound successfully. Mulch heavily to conserve soil moisture.
Imperial County Soil Profile
Soil Type
Loam
Soil pH
5.7-7.3
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 Imperial County
How your county's soil matches Horehound's growing requirements.
Soil pH
Your soil pH (5.7–7.3) overlaps with Horehound's range (6.0–8.0), though not a perfect match.
Soil Texture
The loam soil in Imperial County is excellent for Horehound — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.4%). Annual compost additions will help Horehound.
How to Plant Horehound
Succession Planting Horehound
Sow every 8.6 weeks. Last sowing by Sep 21 to harvest before frost.
Plant Water Budget
Water stress score is 10/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Horehound
Horehound 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 | Horehound Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | 2.2" | 3" | 0" | ✅ Rainfall sufficient |
| Feb | 2.2" | 3.3" | 0" | ✅ Rainfall sufficient |
| Mar | 2.2" | 3.1" | 0" | ✅ Rainfall sufficient |
| Apr | 2.2" | 1.4" | 0.8" | 💧 Light watering |
| May | 2.2" | 0.4" | 1.8" | 🚿 Regular watering |
| Jun | 2.2" | 0.1" | 2.1" | 🚿 Regular watering |
| Jul | 2.2" | 0" | 2.2" | 🚿 Regular watering |
| Aug | 2.2" | 0" | 2.2" | 🚿 Regular watering |
| Sep | 2.2" | 0.2" | 2" | 🚿 Regular watering |
| Oct | 2.2" | 0.6" | 1.6" | 🚿 Regular watering |
| Nov | 2.2" | 1.5" | 0.7" | 💧 Light watering |
| Dec | 2.2" | 3.3" | 0" | ✅ Rainfall sufficient |
Water needs are for active growing months only (Jan–Dec in Imperial County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Horehound 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.
Horehound Planting Timeline — Imperial County, CA
Horehound Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | February 5 | Feb 5 – Feb 19 |
| Harvest | April 23 | Apr 23 – Jun 18 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Transplant Outdoors |
| March | — |
| April | Harvest |
| May | Harvest |
| June | Harvest |
| July | — |
| August | — |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · 1-2 times/week
📅 Days to Maturity
75–90 days
🧪 Soil pH
Needs 6–8 · Your soil: acceptable
🗺️ USDA Zone
Zone 10a
📆 Growing Season
325 days in Imperial County
Growing Tips for Horehound in Imperial County
Direct sow Horehound outdoors after January 29 in Imperial County when soil has warmed and frost danger has passed.
Imperial County receives only 17" of rain annually. Horehound needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Direct sow or start from divisions. Thrives in poor, dry soil. Harvest stems just before flowering. Deadhead to prevent aggressive self-seeding. Very drought-tolerant once established.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Horehound in Other Locations
Frequently Asked Questions
When should I plant Horehound in Imperial County, CA?
Imperial County is in Zone 10a with an average last frost of January 29. Plan your Horehound planting based on this frost date — see the calendar above for exact timing.
What planting zone is Imperial County, CA?
Imperial County, California is in USDA Hardiness Zone 10a. The average last spring frost is January 29 and first fall frost is December 20.
Your Imperial County Garden Planner — Free
A 24-page printable planner built for Imperial County (Zone 10a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.