When to plant Horehound in San Mateo County County,
Plant Horehound in San Mateo County County during the brief January 25–February 8 window. With 329 frost-free days, fall plantings can't mature before December 12.
When to Plant Horehound in San Mateo County, CA
Top priorities for San Mateo County, California gardeners in June
Your garden in San Mateo County, California is working on a schedule, even when you're not. Here's where you should be this June.
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Start harvesting horehound
This is the payoff month. Bring a basket, bring a friend, and get into the beds.
Horehound is a woolly, drought-tolerant perennial herb traditionally used for cough remedies and candy. It has a distinctive bitter, menthol-like flavor.
San Mateo County, California is in USDA Zone 10a. The average last spring frost is January 18 and the first fall frost is December 12, giving you a growing season of approximately 328 days.
At an elevation of 277 feet, San Mateo County receives approximately 16.9 inches of rainfall annually with predominantly loam soil. Summer highs average 81°F, so choose short-season varieties of Horehound to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Horehound successfully. Mulch heavily to conserve soil moisture.
San Mateo County Soil Profile
Soil Type
Loam
Soil pH
6.8-7.2
Drainage
Well Drained
Horehound 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 San Mateo County
How your county's soil matches Horehound's growing requirements.
Soil pH
Your soil pH (6.8–7.2) is within Horehound's preferred range (6.0–8.0).
Soil Texture
The loam soil in San Mateo County is excellent for Horehound — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Horehound.
Organic Matter
Organic matter is moderate (2.6%). Annual compost additions will help Horehound.
How to Plant Horehound
Succession Planting Horehound
Sow every 8.6 weeks. Last sowing by Sep 13 to harvest before frost.
Horehound 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 | 2.2" | 3.9" | 0" | ✅ Rainfall sufficient |
| Feb | 2.2" | 3.4" | 0" | ✅ Rainfall sufficient |
| Mar | 2.2" | 2.7" | 0" | ✅ Rainfall sufficient |
| Apr | 2.2" | 1.2" | 1" | 💧 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" | 0.7" | 1.5" | 🚿 Regular watering |
| Nov | 2.2" | 1.4" | 0.8" | 💧 Light watering |
| Dec | 2.2" | 2.9" | 0" | ✅ Rainfall sufficient |
Water needs are for active growing months only (Jan–Dec in San Mateo 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 — San Mateo County, CA
Horehound Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | January 25 | Jan 25 – Feb 8 |
| Harvest | April 12 | Apr 12 – Jun 7 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Transplant Outdoors |
| 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: ideal
🗺️ USDA Zone
Zone 10a
📆 Growing Season
328 days in San Mateo County
Growing Tips for Horehound in San Mateo County
Direct sow Horehound outdoors after January 18 in San Mateo County when soil has warmed and frost danger has passed.
San Mateo 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 San Mateo County, CA?
San Mateo County is in Zone 10a with an average last frost of January 18. Plan your Horehound planting based on this frost date — see the calendar above for exact timing.
What planting zone is San Mateo County, CA?
San Mateo County, California is in USDA Hardiness Zone 10a. The average last spring frost is January 18 and first fall frost is December 12.
When should I plant Horehound in San Mateo County County, ?
In San Mateo County County, , plant Horehound after the last frost (around January 18) and before the first frost (around December 12). Best results when soil holds above 50°F.
What growing zone is San Mateo County County, for Horehound?
San Mateo County County sits in USDA Zone 10a. Horehound grows reliably in zones 3a through 10b, so it's a good fit here.
Can Horehound grow in San Mateo County County's climate?
Yes — Horehound grows well in San Mateo County County's temperate climate. San Mateo County County averages a 329-day frost-free season, with last frost around January 18 and first frost around December 12.
Your San Mateo County Garden Planner — Free
A 22-page printable planner built for San Mateo 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.