When to Plant Horehound in Marin County, CA
Your May planting checklist for Marin County, California
Welcome to May in Zone 9b. These are the moves that will have the biggest impact on your growing season.
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Harvest horehound as they ripen
Morning harvests are best — cooler temperatures mean crisper produce and longer fridge life.
Coming up in June — start thinking about
- 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.
Marin County, California is in USDA Zone 9b. The average last spring frost is February 26 and the first fall frost is November 26, giving you a growing season of approximately 273 days.
At an elevation of 302 feet, Marin County receives approximately 36 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 81°F, so choose short-season varieties of Horehound to ensure they mature before fall. Sandy soil warms quickly in spring — great for early planting — but Horehound will need more frequent watering and organic matter to retain nutrients.
Marin County Soil Profile
Soil Type
Sandy Loam
Soil pH
6-6.9
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 Marin County
How your county's soil matches Horehound's growing requirements.
Soil pH
Your soil pH (6.0–6.9) is within Horehound's preferred range (6.0–8.0).
Soil Texture
Sandy soil in Marin County warms quickly in spring but drains fast. Horehound will need more frequent watering and regular compost additions to retain nutrients.
Organic Matter
Organic matter is moderate (2.3%). Annual compost additions will help Horehound.
How to Plant Horehound
Succession Planting Horehound
Sow every 8.6 weeks. Last sowing by Aug 28 to harvest before frost.
Plant Water Budget
Water stress score is 8/10 — 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 | — | 7.2" | 0" | ❄️ Dormant |
| Feb | 2.2" | 6.5" | 0" | ✅ Rainfall sufficient |
| Mar | 2.2" | 6.2" | 0" | ✅ Rainfall sufficient |
| Apr | 2.2" | 2.7" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 1" | 1.2" | 🚿 Regular watering |
| Jun | 2.2" | 0.2" | 2" | 🚿 Regular watering |
| Jul | 2.2" | 0" | 2.2" | 🚿 Regular watering |
| Aug | 2.2" | 0" | 2.2" | 🚿 Regular watering |
| Sep | 2.2" | 0.4" | 1.8" | 🚿 Regular watering |
| Oct | 2.2" | 1.4" | 0.8" | 💧 Light watering |
| Nov | 2.2" | 3.5" | 0" | ✅ Rainfall sufficient |
| Dec | — | 6.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Feb–Nov in Marin 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 — Marin County, CA
Horehound Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | March 5 | Mar 5 – Mar 19 |
| Harvest | May 21 | May 21 – Jul 16 |
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
75–90 days
🧪 Soil pH
Needs 6–8 · Your soil: ideal
🗺️ USDA Zone
Zone 9b
📆 Growing Season
273 days in Marin County
Growing Tips for Horehound in Marin County
Direct sow Horehound outdoors after February 26 in Marin County when soil has warmed and frost danger has passed.
Sandy soil in Marin County dries quickly — mulch Horehound with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.
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 Marin County, CA?
Marin County is in Zone 9b with an average last frost of February 26. Plan your Horehound planting based on this frost date — see the calendar above for exact timing.
What planting zone is Marin County, CA?
Marin County, California is in USDA Hardiness Zone 9b. The average last spring frost is February 26 and first fall frost is November 26.
Your Marin County Garden Planner — Free
A 24-page printable planner built for Marin County (Zone 9b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.