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When to Plant Romanesco in Macoupin County, IL

Macoupin County, Illinois Zone 6b May

Your May planting checklist for Macoupin County, Illinois

Your garden in Macoupin County, Illinois is working on a schedule, even when you're not. Here's where you should be this May.

Avg. last frost April 11
Avg. first frost October 21
Soil temp (4") 64°F
Watering Low
Pest pressure Low
Daylight 14.2 hrs
  1. Start romanesco under lights

    These need a head start before your last frost (April 11). Sow into cells now so you're ready to transplant in a few weeks.

Looking ahead to June
  • First harvests: romanesco

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Romanesco is a stunning brassica with a lime-green head composed of fractal-patterned spiraling florets. It has a nuttier, milder flavor than cauliflower.

Macoupin County, Illinois is in USDA Zone 6b. The average last spring frost is April 11 and the first fall frost is October 21, giving you a growing season of approximately 193 days.

At an elevation of 859 feet, Macoupin County receives approximately 30.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Romanesco during the growing season.

Macoupin County, IL (Zone 6b) Moderate season
193 days
Last Spring Frost April 11
193 growing days
First Fall Frost October 21

Macoupin County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (76 days to spare)
Start indoors: Feb 28 Transplant: Apr 4 🍅 Harvest: Jun 20 – Aug 1
Recommended (50%) ✓ Fits season (74 days to spare)
Start indoors: Mar 7 Transplant: Apr 11 🍅 Harvest: Jun 27 – Aug 8
Safe Start (90%) ✓ Fits season (79 days to spare)
Start indoors: Mar 16 Transplant: Apr 20 🍅 Harvest: Jul 6 – Aug 17

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 Macoupin County

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

Soil pH

Your soil pH (6.0–7.2) overlaps with Romanesco's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.0%) — Romanesco will thrive.

How to Plant Romanesco

1"
Planting Depth
15"
Between Plants
24"
Between Rows

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

Succession Planting Romanesco

2
successive plantings in your 193-day season

Sow every 8.6 weeks. Last sowing by Jul 13 to harvest before frost.

For a dedicated fall crop, sow by Aug 12.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.7″/week
You supply
0.3″/week
Watering frequency 1-2 times/week
Season total 563 gal / 100 sq ft

Monthly Watering Guide for Romanesco

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

Month Romanesco Needs Rainfall You Supplement Action
Jan 1.3" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 4.3" 2.7" 1.6" 💧 Light watering
May 4.3" 3.8" 0.5" 💧 Light watering
Jun 4.3" 4.3" 0" ✅ Rainfall sufficient
Jul 4.3" 3" 1.3" 💧 Light watering
Aug 4.3" 3.6" 0.7" 💧 Light watering
Sep 4.3" 2.7" 1.6" 💧 Light watering
Oct 4.3" 2.1" 2.2" 🚿 Regular watering
Nov 2" 0" ❄️ Dormant
Dec 1.6" 0" ❄️ Dormant

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

Romanesco 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.

Romanesco needs ~1,531 GDD — county provides 3,377 GDD Excellent fit

Romanesco Planting Timeline — Macoupin County, IL

Romanesco Planting Calendar

Activity When Date Range
Start Indoors March 7 Mar 7 – Mar 21
Transplant Outdoors April 11 Apr 11 – Apr 25
Direct Sow March 28 Mar 28 – Apr 18
Harvest June 27 Jun 27 – Aug 8
Fall Sowing August 12 Aug 12 – Aug 26

Plant 1" deep · 15" apart · Rows 24" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

75–100 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 6b

📆 Growing Season

193 days in Macoupin County

Growing Tips for Romanesco in Macoupin County

Direct sow Romanesco outdoors after April 11 in Macoupin County when soil has warmed and frost danger has passed.

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

General growing tips

Start seeds indoors 5-7 weeks before transplanting. Provide consistent moisture and avoid temperature stress. Harvest when head is fully formed but before florets begin to separate.

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes
  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Romanesco in Macoupin County, IL?

Macoupin County is in Zone 6b with an average last frost of April 11. Plan your Romanesco planting based on this frost date — see the calendar above for exact timing.

What planting zone is Macoupin County, IL?

Macoupin County, Illinois is in USDA Hardiness Zone 6b. The average last spring frost is April 11 and first fall frost is October 21.

🌱

Your Macoupin County Garden Planner — Free

A 24-page printable planner built for Macoupin County (Zone 6b). 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 Macoupin County, IL. Local conditions may vary. Last updated: May 2026.

Sources & credits

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