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When to Plant Borage in Palmer, AK

Palmer, Alaska Zone 4a April

What to do in April

Each item below is timed to Palmer, Alaska's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost May 17
Avg. first frost September 18
Soil temp (4") 37°F
Watering High
Pest pressure Low
Daylight 14.5 hrs
Looking ahead to May
  • Transplants going out: borage
  • Direct-sowing: borage

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Borage is a self-seeding annual herb with star-shaped blue flowers that attract pollinators. Its leaves have a cucumber-like flavor and the flowers are edible.

Palmer, Alaska is in USDA Zone 4a. The average last spring frost is May 17 and the first fall frost is September 18, giving you a growing season of approximately 124 days.

At an elevation of 1,177 feet, Palmer receives approximately 52.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 69°F, so choose short-season varieties of Borage to ensure they mature before fall. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Borage root diseases.

Palmer, AK (Zone 4a) Short season
124 days
Last Spring Frost May 17
124 growing days
First Fall Frost September 18
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Palmer Soil Profile

Soil Type

Silt Loam

Soil pH

4.9-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (24 days to spare)
Start indoors: Mar 29 Transplant: May 3 🍅 Harvest: Jun 28 – Aug 16
Recommended (50%) ✓ Fits season (26 days to spare)
Start indoors: Apr 5 Transplant: May 10 🍅 Harvest: Jul 5 – Aug 23
Safe Start (90%) ✓ Fits season (14 days to spare)
Start indoors: Apr 27 Transplant: Jun 1 🍅 Harvest: Jul 27 – Sep 14

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 Palmer

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

Soil pH

Your soil pH (4.9–6.7) is more acidic than Borage prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

The silt loam soil in Palmer is excellent for Borage — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Borage prefers dry conditions but your soil drains poorly. Use raised beds or mounded rows to prevent root rot.

Organic Matter

Organic matter is excellent (6.8%) — Borage will thrive.

How to Plant Borage

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Succession Planting Borage

2
successive plantings in your 124-day season

Sow every 5.7 weeks. Last sowing by Jul 20 to harvest before frost.

For a dedicated fall crop, sow by Jun 26.

Plant Water Budget

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

Monthly Watering Guide for Borage

Borage 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 Borage Needs Rainfall You Supplement Action
Jan 2.5" 0" ❄️ Dormant
Feb 2.5" 0" ❄️ Dormant
Mar 2.2" 0" ❄️ Dormant
Apr 1.6" 0" ❄️ Dormant
May 2.2" 2.2" 0" ✅ Rainfall sufficient
Jun 2.2" 4.3" 0" ✅ Rainfall sufficient
Jul 2.2" 7.4" 0" ✅ Rainfall sufficient
Aug 2.2" 7.7" 0" ✅ Rainfall sufficient
Sep 2.2" 8.3" 0" ✅ Rainfall sufficient
Oct 6.5" 0" ❄️ Dormant
Nov 3.9" 0" ❄️ Dormant
Dec 3.3" 0" ❄️ Dormant

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

Borage 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.

Borage needs ~96 GDD — county provides 217 GDD Excellent fit

Borage Planting Timeline — Palmer, AK

Borage Planting Calendar

Activity When Date Range
Start Indoors April 5 Apr 5 – Apr 19
Transplant Outdoors May 10 May 10 – May 24
Direct Sow May 10 May 10 – May 31
Harvest July 5 Jul 5 – Aug 23
Fall Sowing June 26 Jun 26 – Jul 10

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

50–60 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 4a

📆 Growing Season

124 days in Palmer

Growing Tips for Borage in Palmer

Direct sow Borage outdoors after May 17 in Palmer when soil has warmed and frost danger has passed.

General growing tips

Direct sow in spring as borage does not transplant well. Allow some plants to go to seed for next year. Young leaves are best; older leaves become bristly.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Borage in Palmer, AK?

Palmer is in Zone 4a with an average last frost of May 17. Plan your Borage planting based on this frost date — see the calendar above for exact timing.

What planting zone is Palmer, AK?

Palmer, Alaska is in USDA Hardiness Zone 4a. The average last spring frost is May 17 and first fall frost is September 18.

🌱

Your Palmer Garden Planner — Free

A 24-page printable planner built for Palmer (Zone 4a). 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 Palmer, AK. Local conditions may vary. Last updated: April 2026.

Sources & credits

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