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When to Plant Tomatoes in Plumas County, CA

Plumas County, California Zone 7b May

Top priorities for Plumas County, California gardeners in May

Your Plumas County, California garden is entering a new phase. Here's what's on the schedule for May and why each task matters now.

Avg. last frost May 20
Avg. first frost October 8
Soil temp (4") 64°F
Watering Critical
Pest pressure Low
Daylight 14.2 hrs
  1. Scatter tomatoes into prepared beds

    Rake a smooth bed, make a shallow furrow, drop seeds at the spacing on the packet, water gently, walk away.

A few tasks this May that'll pay off in June
  • Transplants going out: tomatoes

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Tomatoes are the most popular home garden crop, available in thousands of varieties from tiny cherries to massive beefsteaks. They are warm-season plants needing full sun.

Plumas County, California is in USDA Zone 7b. The average last spring frost is May 20 and the first fall frost is October 8, giving you a growing season of approximately 141 days.

At an elevation of 1,185 feet, Plumas County receives approximately 30.9 inches of rainfall annually with predominantly loam soil. Summer highs average 82°F, so choose short-season varieties of Tomatoes to ensure they mature before fall.

Plumas County, CA (Zone 7b) Short season
141 days
Last Spring Frost May 20
141 growing days
First Fall Frost October 8

Plumas County Soil Profile

Soil Type

Loam

Soil pH

6.6-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 23 Transplant: May 25 🍅 Harvest: Jul 27 – Oct 5
Recommended (50%) ✗ May not fit
Start indoors: Apr 1 Transplant: Jun 3 🍅 Harvest: Aug 5 – Oct 14
Safe Start (90%) ✗ May not fit
Start indoors: Apr 20 Transplant: Jun 22 🍅 Harvest: Aug 24 – Nov 2

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 Plumas County

How your county's soil matches Tomatoes's growing requirements.

Soil pH

Your soil pH (6.6–7.6) is more alkaline than Tomatoes prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Plumas County is excellent for Tomatoes — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.5%). Annual compost additions will help Tomatoes.

How to Plant Tomatoes

0.5"
Planting Depth
24"
Between Plants
36"
Between Rows

Succession Planting Tomatoes

2
successive plantings in your 141-day season

Sow every 6.9 weeks. Last sowing by Jul 15 to harvest before frost.

Plant Water Budget

Plant needs
1.2″/week
Rainfall provides
0.9″/week
You supply
0.3″/week
Watering frequency 1-2 times/week
Season total 421 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Tomatoes

Tomatoes needs approximately 1.2 inches of water per week (5.2" per month). Here's how your county's rainfall compares month by month.

Month Tomatoes Needs Rainfall You Supplement Action
Jan 6.9" 0" ❄️ Dormant
Feb 6.2" 0" ❄️ Dormant
Mar 5" 0" ❄️ Dormant
Apr 2.4" 0" ❄️ Dormant
May 5.2" 1" 4.2" 🚿 Regular watering
Jun 5.2" 0.2" 5" 🚿 Regular watering
Jul 5.2" 0" 5.2" 🚿 Regular watering
Aug 5.2" 0" 5.2" 🚿 Regular watering
Sep 5.2" 0.3" 4.9" 🚿 Regular watering
Oct 5.2" 1.2" 4" 🚿 Regular watering
Nov 3" 0" ❄️ Dormant
Dec 4.8" 0" ❄️ Dormant

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

Tomatoes 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.

Tomatoes needs ~834 GDD — county provides 1,621 GDD Excellent fit

Tomatoes Planting Timeline — Plumas County, CA

Tomatoes Planting Calendar

Activity When Date Range
Start Indoors April 1 Apr 1 – Apr 15
Transplant Outdoors June 3 Jun 3 – Jun 17
Direct Sow May 27 May 27 – Jun 17
Harvest August 5 Aug 5 – Oct 14

Plant 0.5" deep · 24" apart · Rows 36" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.2"/week · 1-2 times/week

📅 Days to Maturity

60–85 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 7b

📆 Growing Season

141 days in Plumas County

Growing Tips for Tomatoes in Plumas County

Direct sow Tomatoes outdoors after May 20 in Plumas County when soil has warmed and frost danger has passed.

Common pests for Tomatoes in this region include tomato hornworm and aphids. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors 6-8 weeks before last frost. Bury transplants deep to encourage rooting along the stem. Provide consistent moisture to prevent blossom end rot and cracking.

Recommended Tomatoes Varieties for Plumas County

Choose determinate, early-maturing varieties for your short season

Early Girl (52d) Stupice (55d) Glacier (55d) Sub Arctic Plenty (45d)

Companion Planting

Good Companions

Avoid Planting Near

  • Cabbage
  • Fennel
  • Potatoes

Check more plant combinations with our Companion Planting Checker →

🌾 Save Your Own Tomatoes Seeds
Life Cycle Annual
Pollination Self-Pollinating
How to Collect Scoop seeds from ripe fruit; ferment 2-3 days to remove gel coating.
Storage Store airtight; viable 4-6 years at 35°F, under 45% humidity.

Isolate 25 ft between varieties for purity. Use open-pollinated varieties for true-to-type seeds.

Frequently Asked Questions

When should I plant Tomatoes in Plumas County, CA?

Plumas County is in Zone 7b with an average last frost of May 20. Plan your Tomatoes planting based on this frost date — see the calendar above for exact timing.

What planting zone is Plumas County, CA?

Plumas County, California is in USDA Hardiness Zone 7b. The average last spring frost is May 20 and first fall frost is October 8.

🌱

Your Plumas County Garden Planner — Free

A 24-page printable planner built for Plumas County (Zone 7b). 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 Plumas 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.