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When to Plant Begonias in Kitsap County, WA

Kitsap County, Washington Zone 9a July

Your July gardening checklist

Each item below is timed to Kitsap County, Washington's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost March 25
Avg. first frost November 5
Soil temp (4") 89°F
Watering Critical
Pest pressure High
Daylight 15.4 hrs
  1. Start harvesting begonias

    If you can't use it all right away, check the food-preservation section of your planner.

Before August arrives, get these ready
  • 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.

Kitsap County, Washington is in USDA Zone 9a. The average last spring frost is March 25 and the first fall frost is November 5, giving you a growing season of approximately 225 days.

At an elevation of 264 feet, Kitsap County receives approximately 38 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Begonias during the growing season.

Annual Blooms in Multi-season Pollinator-friendly Deer-resistant
Kitsap County, WA (Zone 9a) Long season
225 days
Last Spring Frost March 25
225 growing days
First Fall Frost November 5

Kitsap County Soil Profile

Soil Type

Silt Loam

Soil pH

5.3-6.3

Drainage

Well Drained

Begonias Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Jan 9 Transplant: Feb 27 🌸 Bloom: May 8 – Nov 6
Recommended (50%) ✗ May not fit
Start indoors: Jan 14 Transplant: Mar 4 🌸 Bloom: May 13 – Nov 11
Safe Start (90%) ✗ May not fit
Start indoors: Feb 4 Transplant: Mar 25 🌸 Bloom: Jun 3 – Dec 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 Kitsap County

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

Soil pH

Your soil pH (5.3–6.3) overlaps with Begonias's range (5.5–6.5), though not a perfect match.

Soil Texture

The silt loam soil in Kitsap County is excellent for Begonias — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (4.5%) — Begonias will thrive.

How to Plant Begonias

8"
Between Plants
10"
Between Rows

Succession Planting Begonias

3
successive plantings in your 225-day season

Sow every 8 weeks. Last sowing by Aug 07 to harvest before frost.

Begonias Water Budget

Plant needs
1.0″/week
Rainfall provides
0.7″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 582 gal / 100 sq ft

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 5.1" 0" ❄️ Dormant
Feb 4.5" 0" ❄️ Dormant
Mar 4.3" 4.3" 0" ✅ Rainfall sufficient
Apr 4.3" 2.7" 1.6" 💧 Light watering
May 4.3" 2" 2.3" 🚿 Regular watering
Jun 4.3" 1.3" 3" 🚿 Regular watering
Jul 4.3" 0.7" 3.6" 🚿 Regular watering
Aug 4.3" 0.7" 3.6" 🚿 Regular watering
Sep 4.3" 1.4" 2.9" 🚿 Regular watering
Oct 4.3" 2.9" 1.4" 💧 Light watering
Nov 4.3" 6.5" 0" ✅ Rainfall sufficient
Dec 6" 0" ❄️ Dormant

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

Begonias 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.

Begonias needs ~1,100 GDD — county provides 3,093 GDD Excellent fit

Begonias Planting Timeline — Kitsap County, WA

Begonias Planting Calendar

Activity When Date Range
Start Indoors January 14 Jan 14 – Jan 28
Transplant Outdoors March 4 Mar 4 – Mar 18
Bloom May 13 May 13 – Nov 11

· 8" apart · Rows 10" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

70–90 days

🧪 Soil pH

Needs 5.5–6.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 9a

📆 Growing Season

225 days in Kitsap County

Growing Tips for Begonias in Kitsap County

Direct sow Begonias outdoors after March 25 in Kitsap County when soil has warmed and frost danger has passed.

General growing tips

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 Kitsap County, WA?

Kitsap County is in Zone 9a with an average last frost of March 25. Plan your Begonias planting based on this frost date — see the calendar above for exact timing.

What planting zone is Kitsap County, WA?

Kitsap County, Washington is in USDA Hardiness Zone 9a. The average last spring frost is March 25 and first fall frost is November 5.

🌱

Your Kitsap County Garden Planner — Free

A 22-page printable planner built for Kitsap County (Zone 9a). 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 Kitsap County, WA. 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.