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When to plant Geraniums in Modoc County County,

In Modoc County County, Geraniums is a single-season spring crop — there's no second fall window. Plant June 7–June 21 for an 100-day harvest, finishing well before the September 21 first frost.

When to Plant Geraniums in Modoc County, CA

Modoc County, California Zone 6b June

What to do in June

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

Avg. last frost May 31
Avg. first frost September 21
Soil temp (4") 68°F
Watering Critical
Pest pressure High
Daylight 15 hrs
  1. Set out geraniums seedlings

    Frost risk is low now in Modoc County, California. If you've been covering beds overnight, you can stop.

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Geraniums (Pelargonium × hortorum) are tender perennials grown as warm-season annuals throughout North America. Prized for their bold flower clusters, long bloom period, and tolerance of summer heat when planted in well-drained soil, they anchor window boxes, containers, and bed borders from late spring until hard frost. Zones 9b–11b can overwinter plants in the ground.

Modoc County, California is in USDA Zone 6b. The average last spring frost is May 31 and the first fall frost is September 21, giving you a growing season of approximately 113 days.

At an elevation of 2,205 feet, Modoc County receives approximately 28.3 inches of rainfall annually with predominantly loam soil. Summer highs average 83°F, so choose short-season varieties of Geraniums to ensure they mature before fall.

Annual Blooms in Multi-season Pollinator-friendly Deer-resistant Good for cutting Fragrant
Modoc County, CA (Zone 6b) Short season
113 days
Last Spring Frost May 31
113 growing days
First Fall Frost September 21
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Modoc County Soil Profile

Soil Type

Loam

Soil pH

5.9-7.4

Drainage

Well Drained

Geraniums Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 10 Transplant: May 26 🌸 Bloom: Aug 4 – Nov 10
Recommended (50%) ✗ May not fit
Start indoors: Mar 22 Transplant: Jun 7 🌸 Bloom: Aug 16 – Nov 22
Safe Start (90%) ✗ May not fit
Start indoors: Apr 10 Transplant: Jun 26 🌸 Bloom: Sep 4 – Dec 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 Modoc County

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

Soil pH

Your soil pH (5.9–7.4) overlaps with Geraniums's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Drainage

Drainage is adequate for Geraniums.

Organic Matter

Organic matter is moderate (2.1%). Annual compost additions will help Geraniums.

How to Plant Geraniums

0.1"
Planting Depth
12"
Between Plants
14"
Between Rows

Geraniums Water Budget

Plant needs
1.0″/week
Rainfall provides
1.1″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 299 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Geraniums

Geraniums needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Geraniums Needs Rainfall You Supplement Action
Jan 5.6" 0" ❄️ Dormant
Feb 5.8" 0" ❄️ Dormant
Mar 4.1" 0" ❄️ Dormant
Apr 2.1" 0" ❄️ Dormant
May 4.3" 0.7" 3.6" 🚿 Regular watering
Jun 4.3" 0.1" 4.2" 🚿 Regular watering
Jul 4.3" 0" 4.3" 🚿 Regular watering
Aug 4.3" 0" 4.3" 🚿 Regular watering
Sep 4.3" 0.4" 3.9" 🚿 Regular watering
Oct 1.3" 0" ❄️ Dormant
Nov 2.7" 0" ❄️ Dormant
Dec 5.5" 0" ❄️ Dormant

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

Geraniums 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.

Geraniums needs ~1,041 GDD — county provides 1,384 GDD Excellent fit

Geraniums Planting Timeline — Modoc County, CA

Geraniums Planting Calendar

Activity When Date Range
Start Indoors March 22 Mar 22 – Apr 5
Transplant Outdoors June 7 Jun 7 – Jun 21
Bloom August 16 Aug 16 – Nov 22

Plant 0.1" deep · 12" apart · Rows 14" apart

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April Start Indoors
May
June Transplant Outdoors
July
August Bloom
September Bloom
October Bloom
November Bloom
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

70–100 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 6b

📆 Growing Season

113 days in Modoc County

Growing Tips for Geraniums in Modoc County

Direct sow Geraniums outdoors after May 31 in Modoc County when soil has warmed and frost danger has passed.

Your 113.0-day growing season in Modoc County is tight for Geraniums (70.0-100.0 days to maturity). Start indoors and choose early-maturing varieties.

General growing tips

Start seeds indoors 10–12 weeks before last frost — germination is slow and erratic without bottom heat (70–75°F). Transplant after frost danger passes. Geraniums rarely direct-sown; cuttings or transplants are the standard. Deadhead spent umbels weekly to maintain continuous bloom. Let soil dry slightly between waterings to prevent root rot. In zones 10–11 plants may be left in ground year-round or overwintered as houseplants.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Geraniums in Modoc County, CA?

Modoc County is in Zone 6b with an average last frost of May 31. Plan your Geraniums planting based on this frost date — see the calendar above for exact timing.

What planting zone is Modoc County, CA?

Modoc County, California is in USDA Hardiness Zone 6b. The average last spring frost is May 31 and first fall frost is September 21.

When should I plant Geraniums in Modoc County County, ?

In Modoc County County, , plant Geraniums after the last frost (around May 31) and before the first frost (around September 21). Best results when soil holds above 50°F.

What growing zone is Modoc County County, for Geraniums?

Modoc County County sits in USDA Zone 6b. Geraniums grows reliably in zones 2a through 11b, so it's a good fit here.

Can Geraniums grow in Modoc County County's climate?

Yes — Geraniums grows well in Modoc County County's temperate climate. Modoc County County averages a 113-day frost-free season, with last frost around May 31 and first frost around September 21.

🌱

Your Modoc County Garden Planner — Free

A 22-page printable planner built for Modoc 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 Modoc County, CA. Local conditions may vary. Last updated: June 2026.

Sources & credits

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