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When to plant Begonias in Juneau City and Borough County,

Plant Begonias in Juneau City and Borough County, between May 3 and May 17 — the only viable window. Zone 7a's short season (152 frost-free days) rules out a fall crop.

When to Plant Begonias in Juneau City and Borough, AK

Juneau City and Borough, Alaska Zone 7a June

June to-do list for Juneau City and Borough, Alaska

Welcome to June in Zone 7a. These are the moves that will have the biggest impact on your growing season.

Avg. last frost May 3
Avg. first frost October 2
Soil temp (4") 76°F
Watering Moderate
Pest pressure High
Daylight 17.9 hrs
July will be here before you know it — start on
  • Starting indoors: begonias
  • 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.

Juneau City and Borough, Alaska is in USDA Zone 7a. The average last spring frost is May 3 and the first fall frost is October 2, giving you a growing season of approximately 152 days.

At an elevation of 930 feet, Juneau City and Borough receives approximately 35.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 57°F, so choose short-season varieties of Begonias to ensure they mature before fall.

Annual Blooms in Multi-season Pollinator-friendly Deer-resistant
Juneau City and Borough, AK (Zone 7a) Moderate season
152 days
Last Spring Frost May 3
152 growing days
First Fall Frost October 2
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Juneau City and Borough Soil Profile

Soil Type

Silt Loam

Soil pH

5.1-6.5

Drainage

Well Drained

Begonias Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Feb 16 Transplant: Apr 27 🌸 Bloom: Jul 6 – Oct 26
Recommended (50%) ✗ May not fit
Start indoors: Feb 22 Transplant: May 3 🌸 Bloom: Jul 12 – Nov 1
Safe Start (90%) ✗ May not fit
Start indoors: Mar 8 Transplant: May 17 🌸 Bloom: Jul 26 – Nov 15

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 Juneau City and Borough

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

Soil pH

Your soil pH (5.1–6.5) overlaps with Begonias's range (5.5–6.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (6.7%) — Begonias will thrive.

How to Plant Begonias

8"
Between Plants
10"
Between Rows

Succession Planting Begonias

2
successive plantings in your 152-day season

Sow every 8 weeks. Last sowing by Jul 04 to harvest before frost.

Begonias Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 15 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 2" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 1.3" 0" ❄️ Dormant
Apr 1" 0" ❄️ Dormant
May 4.3" 1.6" 2.7" 🚿 Regular watering
Jun 4.3" 3.1" 1.2" 💧 Light watering
Jul 4.3" 4.4" 0" ✅ Rainfall sufficient
Aug 4.3" 5.3" 0" ✅ Rainfall sufficient
Sep 4.3" 6.5" 0" ✅ Rainfall sufficient
Oct 4.3" 4.1" 0.2" 💧 Light watering
Nov 2.7" 0" ❄️ Dormant
Dec 2.3" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Juneau City and Borough). 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 ~0 GDD — county provides 0 GDD May not mature

Begonias Planting Timeline — Juneau City and Borough, AK

Begonias Planting Calendar

Activity When Date Range
Start Indoors February 22 Feb 22 – Mar 8
Transplant Outdoors May 3 May 3 – May 17
Bloom July 12 Jul 12 – Nov 1

· 8" apart · Rows 10" apart

Month-by-Month Timeline

MonthActivities
January
February Start Indoors
March Start Indoors
April
May Transplant Outdoors
June
July Bloom
August Bloom
September Bloom
October Bloom
November Bloom
December
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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 7a

📆 Growing Season

152 days in Juneau City and Borough

Growing Tips for Begonias in Juneau City and Borough

Direct sow Begonias outdoors after May 03 in Juneau City and Borough 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 Juneau City and Borough, AK?

Juneau City and Borough is in Zone 7a with an average last frost of May 3. Plan your Begonias planting based on this frost date — see the calendar above for exact timing.

What planting zone is Juneau City and Borough, AK?

Juneau City and Borough, Alaska is in USDA Hardiness Zone 7a. The average last spring frost is May 3 and first fall frost is October 2.

When should I plant Begonias in Juneau City and Borough County, ?

In Juneau City and Borough County, , plant Begonias after the last frost (around May 3) and before the first frost (around October 2). Best results when soil holds above 50°F.

What growing zone is Juneau City and Borough County, for Begonias?

Juneau City and Borough County sits in USDA Zone 7a. Begonias grows reliably in zones 2a through 11b, so it's a good fit here.

Can Begonias grow in Juneau City and Borough County's climate?

Yes — Begonias grows well in Juneau City and Borough County's temperate climate. Juneau City and Borough County averages a 152-day frost-free season, with last frost around May 3 and first frost around October 2.

🌱

Your Juneau City and Borough Garden Planner — Free

A 22-page printable planner built for Juneau City and Borough (Zone 7a). 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 Juneau City and Borough, AK. 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.