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When to Plant Mustard Greens in Sierra County, CA

Sierra County, California Zone 6b May

May in Sierra County, California — your action list

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

Avg. last frost May 10
Avg. first frost October 22
Soil temp (4") 62°F
Watering Critical
Pest pressure Low
Daylight 14.2 hrs
  1. Transplant mustard greens outside

    Plant tomatoes deep — bury the stem up to the first true leaves to grow extra roots. Everything else goes in at the same depth it grew in the tray.

June will be here before you know it — start on
  • Starting indoors: mustard greens
  • First harvests: mustard greens

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Mustard greens are fast-growing brassicas with a spicy, peppery kick. They come in green, red, and purple varieties and are excellent cooked or in salads.

Sierra County, California is in USDA Zone 6b. The average last spring frost is May 10 and the first fall frost is October 22, giving you a growing season of approximately 165 days.

At an elevation of 1,560 feet, Sierra County receives approximately 40.5 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Mustard Greens to ensure they mature before fall.

Sierra County, CA (Zone 6b) Moderate season
165 days
Last Spring Frost May 10
165 growing days
First Fall Frost October 22
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Sierra County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (66 days to spare)
Start indoors: Mar 21 Transplant: Apr 25 🍅 Harvest: May 30 – Aug 1
Recommended (50%) ✓ Fits season (67 days to spare)
Start indoors: Apr 5 Transplant: May 10 🍅 Harvest: Jun 14 – Aug 16
Safe Start (90%) ✓ Fits season (75 days to spare)
Start indoors: May 1 Transplant: Jun 5 🍅 Harvest: Jul 10 – Sep 11

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 Sierra County

How your county's soil matches Mustard Greens's growing requirements.

Soil pH

Your soil pH (6.7–7.3) overlaps with Mustard Greens's range (6.0–7.0), though not a perfect match.

Soil Texture

The loam soil in Sierra County is excellent for Mustard Greens — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (3.0%). Annual compost additions will help Mustard Greens.

How to Plant Mustard Greens

0.5"
Planting Depth
6"
Between Plants
12"
Between Rows

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Succession Planting Mustard Greens

6
successive plantings in your 165-day season

Sow every 3.4 weeks. Last sowing by Sep 02 to harvest before frost.

For a dedicated fall crop, sow by Aug 13.

Plant Water Budget

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

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Mustard Greens

Mustard Greens needs approximately 0.7 inches of water per week (3" per month). Here's how your county's rainfall compares month by month.

Month Mustard Greens Needs Rainfall You Supplement Action
Jan 8.8" 0" ❄️ Dormant
Feb 8.2" 0" ❄️ Dormant
Mar 5.6" 0" ❄️ Dormant
Apr 3.2" 0" ❄️ Dormant
May 3" 1.1" 1.9" 🚿 Regular watering
Jun 3" 0.2" 2.8" 🚿 Regular watering
Jul 3" 0" 3" 🚿 Regular watering
Aug 3" 0" 3" 🚿 Regular watering
Sep 3" 0.4" 2.6" 🚿 Regular watering
Oct 3" 1.9" 1.1" 💧 Light watering
Nov 3.7" 0" ❄️ Dormant
Dec 7.3" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Sierra County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Mustard Greens 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.

Mustard Greens needs ~400 GDD — county provides 1,650 GDD Excellent fit

Mustard Greens Planting Timeline — Sierra County, CA

Mustard Greens Planting Calendar

Activity When Date Range
Start Indoors April 5 Apr 5 – Apr 19
Transplant Outdoors May 10 May 10 – May 24
Direct Sow April 26 Apr 26 – May 17
Harvest June 14 Jun 14 – Aug 16
Fall Sowing August 13 Aug 13 – Aug 27

Plant 0.5" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors Direct Sow
May Transplant Outdoors Direct Sow
June Harvest
July Harvest
August Fall Sowing Harvest
September
October
November
December
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Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.7"/week · Natural rainfall sufficient

📅 Days to Maturity

30–50 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 6b

📆 Growing Season

165 days in Sierra County

Growing Tips for Mustard Greens in Sierra County

Direct sow Mustard Greens outdoors after May 10 in Sierra County when soil has warmed and frost danger has passed.

Your generous 165.0-day season in Sierra County allows multiple plantings of Mustard Greens. Sow every 15.0 days for continuous harvest.

Common pests for Mustard Greens in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow in early spring or fall. Harvest young leaves for milder flavor. Plants bolt quickly in heat so grow as a cool-season crop or provide shade.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Mustard Greens in Sierra County, CA?

Sierra County is in Zone 6b with an average last frost of May 10. Plan your Mustard Greens planting based on this frost date — see the calendar above for exact timing.

What planting zone is Sierra County, CA?

Sierra County, California is in USDA Hardiness Zone 6b. The average last spring frost is May 10 and first fall frost is October 22.

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Your Sierra County Garden Planner — Free

A 24-page printable planner built for Sierra County (Zone 6b). 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 Sierra County, CA. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.