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When to plant Microgreens in Castleton,

In Zone 5b (Castleton), direct-sow Microgreens between April 7 and April 28 for spring, after the April 21 last-frost mark. A second sowing from August 3 to August 17 extends the harvest into fall.

When to Plant Microgreens in Castleton, IL

Castleton, IL Zone 5b June

June to-do list for Castleton, IL

Here's what deserves your attention in Castleton, IL this month. Everything below is tailored to Zone 5b and timed around your local frost dates.

Avg. last frost April 21
Avg. first frost October 12
Soil temp (4") 69°F
Watering Low
Pest pressure High
Daylight 14.9 hrs

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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.

Castleton, Illinois is in USDA Zone 5b. The average last spring frost is April 21 and the first fall frost is October 12, giving you a growing season of approximately 174 days.

At an elevation of 1,071 feet, Stark County receives approximately 33.7 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.

Castleton, IL (Zone 5b) Moderate season
174 days
Last Spring Frost April 21
174 growing days
First Fall Frost October 12

Castleton Soil Profile

Soil Type

Silt Loam

Soil pH

6-6.9

Drainage

Well Drained

Microgreens Planting Risk Windows

Early Start (70% safe) ✓ Fits season (140 days to spare)
Start indoors: Mar 12 Transplant: Apr 16 🍅 Harvest: Apr 23 – May 21
Recommended (50%) ✓ Fits season (139 days to spare)
Start indoors: Mar 17 Transplant: Apr 21 🍅 Harvest: Apr 28 – May 26
Safe Start (90%) ✓ Fits season (137 days to spare)
Start indoors: Apr 3 Transplant: May 8 🍅 Harvest: May 15 – Jun 12

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 Castleton

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

Soil pH

Your soil pH (6.0–6.9) is within Microgreens's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.8%) — 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

34
successive plantings in your 174-day season

Sow every 0.7 weeks. Last sowing by Sep 21 to harvest before frost.

For a dedicated fall crop, sow by Aug 03.

Microgreens Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 289 gal / 100 sq ft

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 1.4" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 2.7" 0" ❄️ Dormant
Apr 4.3" 3.5" 0.8" 💧 Light watering
May 4.3" 4.1" 0.2" 💧 Light watering
Jun 4.3" 4.1" 0.2" 💧 Light watering
Jul 4.3" 3.5" 0.8" 💧 Light watering
Aug 4.3" 3.3" 1" 💧 Light watering
Sep 4.3" 2.8" 1.5" 💧 Light watering
Oct 4.3" 2.9" 1.4" 💧 Light watering
Nov 2.3" 0" ❄️ Dormant
Dec 1.7" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Stark 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 2,262 GDD Excellent fit

Microgreens Planting Timeline — Castleton, IL

Microgreens Planting Calendar

Activity When Date Range
Start Indoors March 17 Mar 17 – Mar 31
Transplant Outdoors April 21 Apr 21 – May 5
Direct Sow April 7 Apr 7 – Apr 28
Harvest April 28 Apr 28 – May 26
Fall Sowing August 3 Aug 3 – Aug 17

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

174 days in Stark County

Growing Tips for Microgreens in Castleton

Direct sow Microgreens outdoors after April 21 in Stark County when soil has warmed and frost danger has passed.

Your generous 174.0-day season in Stark 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 Castleton, ?

In Castleton, , plant Microgreens after the last frost (around April 21) and before the first frost (around October 12). Best results when soil holds above 50°F.

What growing zone is Castleton, for Microgreens?

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

Can Microgreens grow in Castleton's climate?

Yes — Microgreens grows well in Castleton's temperate climate. Castleton averages a 174-day frost-free season, with last frost around April 21 and first frost around October 12.

🌱

Your Stark County Garden Planner — Free

A 22-page printable planner built for Stark 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 Stark County, IL. Local conditions may vary. Last updated: June 2026.