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When to plant Borage in Viola, IL

Plant Borage in Viola after April 17; the prime window is April 3–April 24. A second sowing from August 6 to August 20 extends the harvest into fall.

When to Plant Borage in Viola, IL

Mercer County, Illinois Zone 5b June

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Avg. last frost April 17
Avg. first frost October 15
Soil temp (4") 69°F
Watering Low
Pest pressure High
Daylight 15 hrs
  1. It's harvest week for borage

    Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.

July will be here before you know it — start on
  • First harvests: 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.

Viola, Illinois is in USDA Zone 5b. The average last spring frost is April 17 and the first fall frost is October 15, giving you a growing season of approximately 181 days.

At an elevation of 777 feet, Mercer County receives approximately 37.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Borage to ensure they mature before fall.

Viola, IL (Zone 5b) Moderate season
181 days
Last Spring Frost April 17
181 growing days
First Fall Frost October 15

Viola Soil Profile

Soil Type

Silt Loam

Soil pH

6.3-6.7

Drainage

Well Drained

Borage Planting Risk Windows

Early Start (70% safe) ✓ Fits season (83 days to spare)
Start indoors: Mar 8 Transplant: Apr 5 🍅 Harvest: May 31 – Jul 19
Recommended (50%) ✓ Fits season (83 days to spare)
Start indoors: Mar 13 Transplant: Apr 10 🍅 Harvest: Jun 5 – Jul 24
Safe Start (90%) ✓ Fits season (87 days to spare)
Start indoors: Mar 29 Transplant: Apr 26 🍅 Harvest: Jun 21 – Aug 9

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 Viola

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

Soil pH

Your soil pH (6.3–6.7) is within Borage's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

Organic matter is moderate (4.0%). Annual compost additions will help Borage.

How to Plant Borage

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

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Succession Planting Borage

4
successive plantings in your 181-day season

Sow every 5.7 weeks. Last sowing by Aug 16 to harvest before frost.

For a dedicated fall crop, sow by Aug 06.

Borage Water Budget

Plant needs
0.5″/week
Rainfall provides
0.9″/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 1.8" 0" ❄️ Dormant
Feb 1.8" 0" ❄️ Dormant
Mar 2.9" 0" ❄️ Dormant
Apr 2.2" 3.7" 0" ✅ Rainfall sufficient
May 2.2" 4" 0" ✅ Rainfall sufficient
Jun 2.2" 4.6" 0" ✅ Rainfall sufficient
Jul 2.2" 3.7" 0" ✅ Rainfall sufficient
Aug 2.2" 4" 0" ✅ Rainfall sufficient
Sep 2.2" 3.4" 0" ✅ Rainfall sufficient
Oct 2.2" 2.5" 0" ✅ Rainfall sufficient
Nov 2.6" 0" ❄️ Dormant
Dec 2.2" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Mercer County). 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 ~674 GDD — county provides 2,217 GDD Excellent fit

Borage Planting Timeline — Viola, IL

Borage Planting Calendar

Activity When Date Range
Start Indoors March 13 Mar 13 – Mar 27
Transplant Outdoors April 10 Apr 10 – Apr 24
Direct Sow April 3 Apr 3 – Apr 24
Harvest June 5 Jun 5 – Jul 24
Fall Sowing August 6 Aug 6 – Aug 20

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

Month-by-Month Timeline

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

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: ideal

🗺️ USDA Zone

Zone 5b

📆 Growing Season

181 days in Mercer County

Growing Tips for Borage in Viola

Direct sow Borage outdoors after April 17 in Mercer County 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 →

When should I plant Borage in Viola, IL?

In Viola, IL, plant Borage after the last frost (around April 17) and before the first frost (around October 15). Best results when soil holds above 50°F.

What growing zone is Viola, IL for Borage?

Viola sits in USDA Zone 5b. Borage grows reliably in zones 3a through 11b, so it's a good fit here.

Can Borage grow in Viola's climate?

Yes — Borage grows well in Viola's temperate climate. Viola averages a 181-day frost-free season, with last frost around April 17 and first frost around October 15.

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Your Mercer County Garden Planner — Free

A 22-page printable planner built for Mercer County (Zone 5b). 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 Mercer County, IL. Local conditions may vary. Last updated: June 2026.