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When to plant Sweet Alyssum in Juneau City and Borough County,

Juneau City and Borough County sits in USDA Zone 7a. Plant Sweet Alyssum between April 5 (after last frost on May 3) and April 26. A second sowing from August 21 to September 4 extends the harvest into fall.

When to Plant Sweet Alyssum in Juneau City and Borough, AK

Juneau City and Borough, Alaska Zone 7a June

June in Juneau City and Borough, Alaska — your action list

Your garden in Juneau City and Borough, Alaska is working on a schedule, even when you're not. Here's where you should be this June.

Avg. last frost May 3
Avg. first frost October 2
Soil temp (4") 76°F
Watering Moderate
Pest pressure High
Daylight 17.9 hrs
  1. Fire up the seed-starting tray: sweet alyssum

    Give them 6–8 weeks indoors before the last frost and you'll transplant into warm soil with seedlings that are already leaping.

  2. Collect sweet alyssum at their peak

    Check every 1–2 days. Many of these get tough or go to seed if you wait too long.

Get ahead of July
  • First harvests: sweet alyssum

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Sweet Alyssum (Lobularia maritima) is a low-growing cool-season annual prized for its honey-scented clusters of tiny white, pink, or purple flowers. A workhorse border plant, it tolerates light frost, self-seeds readily, and attracts beneficial insects throughout its bloom season. In warm climates it often re-blooms in fall after summer heat fades.

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 Sweet Alyssum to ensure they mature before fall.

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

Juneau City and Borough Soil Profile

Soil Type

Silt Loam

Soil pH

5.1-6.5

Drainage

Well Drained

Sweet Alyssum Planting Risk Windows

Early Start (70% safe) ✓ Fits season (31 days to spare)
Start indoors: Mar 16 Transplant: Apr 27 🌸 Bloom: Jun 8 – Aug 31
Recommended (50%) ✓ Fits season (26 days to spare)
Start indoors: Mar 22 Transplant: May 3 🌸 Bloom: Jun 14 – Sep 6
Safe Start (90%) ✓ Fits season (33 days to spare)
Start indoors: Apr 5 Transplant: May 17 🌸 Bloom: Jun 28 – Sep 20

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 Sweet Alyssum's growing requirements.

Soil pH

Your soil pH (5.1–6.5) is more acidic than Sweet Alyssum prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

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

How to Plant Sweet Alyssum

6"
Between Plants
8"
Between Rows

Fall planting: Sow 6 weeks before your first frost date for a fall harvest.

Succession Planting Sweet Alyssum

3
successive plantings in your 152-day season

Sow every 5.1 weeks. Last sowing by Aug 03 to harvest before frost.

For a dedicated fall crop, sow by Aug 21.

Sweet Alyssum Water Budget

Plant needs
0.5″/week
Rainfall provides
1.0″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

Monthly Watering Guide for Sweet Alyssum

Sweet Alyssum needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.

Month Sweet Alyssum Needs Rainfall You Supplement Action
Jan 2" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 1.3" 0" ❄️ Dormant
Apr 1" 0" ❄️ Dormant
May 2.2" 1.6" 0.6" 💧 Light watering
Jun 2.2" 3.1" 0" ✅ Rainfall sufficient
Jul 2.2" 4.4" 0" ✅ Rainfall sufficient
Aug 2.2" 5.3" 0" ✅ Rainfall sufficient
Sep 2.2" 6.5" 0" ✅ Rainfall sufficient
Oct 2.2" 4.1" 0" ✅ Rainfall sufficient
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.

Sweet Alyssum 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.

Sweet Alyssum needs ~0 GDD — county provides 0 GDD May not mature

Sweet Alyssum Planting Timeline — Juneau City and Borough, AK

Sweet Alyssum Planting Calendar

Activity When Date Range
Start Indoors March 22 Mar 22 – Apr 5
Transplant Outdoors May 3 May 3 – May 17
Direct Sow April 5 Apr 5 – Apr 26
Bloom June 14 Jun 14 – Sep 6
Fall Sowing August 21 Aug 21 – Sep 4

· 6" apart · Rows 8" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

45–60 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 7a

📆 Growing Season

152 days in Juneau City and Borough

Growing Tips for Sweet Alyssum in Juneau City and Borough

Direct sow Sweet Alyssum outdoors after May 03 in Juneau City and Borough when soil has warmed and frost danger has passed.

Your generous 152.0-day season in Juneau City and Borough allows multiple plantings of Sweet Alyssum. Sow every 22.0 days for continuous harvest.

Common pests for Sweet Alyssum in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Surface-sow seeds — they need light to germinate. Direct-sow as soon as soil can be worked in spring; in zones 7+ also sow in fall. Thin to 6 inches apart. Shear back hard in midsummer when heat causes dormancy — plants recover and re-bloom when cool weather returns. Self-seeds prolifically; allow a few plants to set seed for a perpetual colony.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Sweet Alyssum in Juneau City and Borough, AK?

Juneau City and Borough is in Zone 7a with an average last frost of May 3. Plan your Sweet Alyssum 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 Sweet Alyssum in Juneau City and Borough County, ?

In Juneau City and Borough County, , plant Sweet Alyssum 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 Sweet Alyssum?

Juneau City and Borough County sits in USDA Zone 7a. Sweet Alyssum grows reliably in zones 3a through 11b, so it's a good fit here.

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

Yes — Sweet Alyssum 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.