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When to plant Begonias in Trinity County, CA

Trinity County sits in cold Zone 8b. Plant Begonias April 5–April 19 for the single annual harvest; the October 25 first frost closes the window.

When to Plant Begonias in Trinity County, CA

Trinity County, California Zone 8b July

What to do in July

Here's what deserves your attention in Trinity County, California this month. Everything below is tailored to Zone 8b and timed around your local frost dates.

Avg. last frost April 19
Avg. first frost October 25
Soil temp (4") 84°F
Watering Critical
Pest pressure High
Daylight 14.6 hrs
  1. It's harvest week for begonias

    The more you pick, the more the plant produces. Letting fruit overripen tells the plant it's time to stop.

Looking ahead to August
  • First harvests: begonias

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Wax begonias (Begonia × semperflorens) are the workhorse shade bedding plant of American horticulture, offering continuous bloom from transplant to hard frost. Bronze or green-leaved varieties perform well from deep shade to full sun (in northern zones) and tolerate summer humidity better than most cool- season flowers. A staple of mass plantings, containers, and window boxes.

Trinity County, California is in USDA Zone 8b. The average last spring frost is April 19 and the first fall frost is October 25, giving you a growing season of approximately 189 days.

At an elevation of 61 feet, Trinity County receives approximately 30.9 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 79°F, so choose short-season varieties of Begonias to ensure they mature before fall. Sandy soil warms quickly in spring — great for early planting — but Begonias will need more frequent watering and organic matter to retain nutrients.

Annual Blooms in Multi-season Pollinator-friendly Deer-resistant
Trinity County, CA (Zone 8b) Moderate season
189 days
Last Spring Frost April 19
189 growing days
First Fall Frost October 25

Trinity County Soil Profile

Soil Type

Sandy Loam

Soil pH

6-7.1

Drainage

Well Drained

Monthly Watering Guide for Begonias

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

Month Begonias Needs Rainfall You Supplement Action
Jan 6.2" 0" ❄️ Dormant
Feb 6.6" 0" ❄️ Dormant
Mar 5" 0" ❄️ Dormant
Apr 4.3" 2.7" 1.6" 💧 Light watering
May 4.3" 0.9" 3.4" 🚿 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" 0.3" 4" 🚿 Regular watering
Oct 4.3" 1.2" 3.1" 🚿 Regular watering
Nov 2.9" 0" ❄️ Dormant
Dec 4.9" 0" ❄️ Dormant

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

Begonias Planting Timeline — Trinity County, CA

Begonias Planting Calendar

Activity When Date Range
Start Indoors February 8 Feb 8 – Feb 22
Transplant Outdoors April 5 Apr 5 – Apr 19
Bloom June 14 Jun 14 – Nov 15

· 8" apart · Rows 10" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

Moderate — regular watering

📅 Days to Maturity

70–90 days

🧪 Soil pH

Needs 5.5–6.5 · Your soil: N/A

🗺️ USDA Zone

Zone 8b

📆 Growing Season

189 days in Trinity County

Growing Tips for Trinity County

Start seeds indoors 10–12 weeks before last frost — seed is dust-fine; surface-sow on moist mix under lights, do not cover. Bottom heat (70–75°F) speeds germination. Transplant after frost; begonias are not direct-sown in practice. Pinch seedlings once for branching. Keep soil evenly moist; avoid waterlogged conditions. Bronze-leaf types tolerate more sun; green- leaf types prefer shade to part-sun.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Begonias in Trinity County, CA?

Trinity County is in Zone 8b with an average last frost of April 19. Plan your Begonias planting based on this frost date — see the calendar above for exact timing.

What planting zone is Trinity County, CA?

Trinity County, California is in USDA Hardiness Zone 8b. The average last spring frost is April 19 and first fall frost is October 25.

When should I plant Begonias in Trinity County, CA?

In Trinity County, CA, plant Begonias after the last frost (around April 19) and before the first frost (around October 25). Best results when soil holds above 50°F.

What growing zone is Trinity County, CA for Begonias?

Trinity County sits in USDA Zone 8b. Begonias grows reliably in zones 2a through 11b, so it's a good fit here.

Can Begonias grow in Trinity County's climate?

Yes — Begonias grows well in Trinity County's temperate climate. Trinity County averages a 189-day frost-free season, with last frost around April 19 and first frost around October 25.

🌱

Your Trinity County Garden Planner — Free

A 22-page printable planner built for Trinity County (Zone 8b). 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 Trinity County, CA. Local conditions may vary. Last updated: July 2026.

Sources & credits

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