Blog

When to plant Microgreens in Saint Augustine, IL

Spring Microgreens in Saint Augustine goes in April 3–April 24, once nighttime temps stop dipping near freezing. A second sowing from August 6 to August 20 extends the harvest into fall.

When to Plant Microgreens in Saint Augustine, IL

Knox County, Illinois Zone 5b July

Your July game plan for Knox County, Illinois

July is a pivotal month for Knox County, Illinois gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost April 17
Avg. first frost October 15
Soil temp (4") 78°F
Watering Low
Pest pressure High
Daylight 14.7 hrs
Looking ahead to August
  • Fall sowing: microgreens

Instant PDF download. No spam, unsubscribe any time.

Microgreens are young seedlings of vegetables and herbs harvested at the cotyledon or first true leaf stage. They pack concentrated flavors and nutrients in a tiny package.

Saint Augustine, 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 1,301 feet, Knox County receives approximately 33.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Microgreens to ensure they mature before fall.

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

Saint Augustine Soil Profile

Soil Type

Silt Loam

Soil pH

6-6.8

Drainage

Well Drained

Microgreens Planting Risk Windows

Early Start (70% safe) ✓ Fits season (146 days to spare)
Start indoors: Mar 8 Transplant: Apr 12 🍅 Harvest: Apr 19 – May 17
Recommended (50%) ✓ Fits season (146 days to spare)
Start indoors: Mar 13 Transplant: Apr 17 🍅 Harvest: Apr 24 – May 22
Safe Start (90%) ✓ Fits season (150 days to spare)
Start indoors: Mar 29 Transplant: May 3 🍅 Harvest: May 10 – Jun 7

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 Saint Augustine

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

Soil pH

Your soil pH (6.0–6.8) is within Microgreens's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

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

How to Plant Microgreens

0.5"
Planting Depth
2"
Between Plants
6"
Between Rows

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

Succession Planting Microgreens

35
successive plantings in your 181-day season

Sow every 0.7 weeks. Last sowing by Sep 24 to harvest before frost.

For a dedicated fall crop, sow by Aug 06.

Microgreens Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 444 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Microgreens

Microgreens needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Microgreens Needs Rainfall You Supplement Action
Jan 1.3" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 4.3" 3.4" 0.9" 💧 Light watering
May 4.3" 3.9" 0.4" 💧 Light watering
Jun 4.3" 3.6" 0.7" 💧 Light watering
Jul 4.3" 4.1" 0.2" 💧 Light watering
Aug 4.3" 3.5" 0.8" 💧 Light watering
Sep 4.3" 2.6" 1.7" 💧 Light watering
Oct 4.3" 2.7" 1.6" 💧 Light watering
Nov 2.5" 0" ❄️ Dormant
Dec 1.6" 0" ❄️ Dormant

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

Microgreens 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.

Microgreens needs ~182 GDD — county provides 2,353 GDD Excellent fit

Microgreens Planting Timeline — Saint Augustine, IL

Microgreens Planting Calendar

Activity When Date Range
Start Indoors March 13 Mar 13 – Mar 27
Transplant Outdoors April 17 Apr 17 – May 1
Direct Sow April 3 Apr 3 – Apr 24
Harvest April 24 Apr 24 – May 22
Fall Sowing August 6 Aug 6 – Aug 20

Plant 0.5" deep · 2" apart · Rows 6" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

7–21 days

🧪 Soil pH

Needs 6–7 · Your soil: ideal

🗺️ USDA Zone

Zone 5b

📆 Growing Season

181 days in Knox County

Growing Tips for Microgreens in Saint Augustine

Direct sow Microgreens outdoors after April 17 in Knox County when soil has warmed and frost danger has passed.

Your generous 181.0-day season in Knox County allows multiple plantings of Microgreens. Sow every 3.0 days for continuous harvest.

General growing tips

Sow seeds densely on shallow trays of moist growing medium. Cover until germination, then provide light. Harvest with scissors when 1-3 inches tall. Grow year-round indoors.

When should I plant Microgreens in Saint Augustine, IL?

In Saint Augustine, IL, plant Microgreens 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 Saint Augustine, IL for Microgreens?

Saint Augustine sits in USDA Zone 5b. Microgreens grows reliably in zones 1a through 13b, so it's a good fit here.

Can Microgreens grow in Saint Augustine's climate?

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

🌱

Your Knox County Garden Planner — Free

A 22-page printable planner built for Knox 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.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Knox County, IL. Local conditions may vary. Last updated: July 2026.