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When to Plant Romanesco in Union County, IN

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

Union County, Indiana is in USDA Zone 6a. The average last spring frost is April 25 and the first fall frost is October 17, giving you a growing season of approximately 175 days.

At an elevation of 506 feet, Union County receives approximately 33.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90ยฐF, providing good warmth for Romanesco during the growing season.

Union County, IN (Zone 6a) Moderate season
175 days
Last Spring Frost April 25
175 growing days
First Fall Frost October 17

Union County Soil Profile

Soil Type

Silt Loam

Soil pH

5.7-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (58 days to spare)
Start indoors: Mar 13 Transplant: Apr 17 🍅 Harvest: Jul 3 – Aug 14
Recommended (50%) ✓ Fits season (56 days to spare)
Start indoors: Mar 21 Transplant: Apr 25 🍅 Harvest: Jul 11 – Aug 22
Safe Start (90%) ✓ Fits season (52 days to spare)
Start indoors: Apr 4 Transplant: May 9 🍅 Harvest: Jul 25 – Sep 5

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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 773 gal / 100 sq ft
Romanesco needs ~1,531 GDD — county provides 3,062 GDD Excellent fit

Romanesco Planting Timeline โ€” Union County, IN

Romanesco Planting Calendar

Activity When Date Range
Start Indoors March 21 Mar 21 โ€“ Apr 4
Transplant Outdoors April 25 Apr 25 โ€“ May 9
Direct Sow April 11 Apr 11 โ€“ May 2
Fall Sowing August 8 Aug 8 โ€“ Aug 22
Harvest July 11 Jul 11 โ€“ Aug 22

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

75โ€“100 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 6a

Growing Season

175 days

Growing Tips for Union County

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

Level Up Your Garden

Frequently Asked Questions

When should I plant Romanesco in Union County, IN?

Union County is in Zone 6a with an average last frost of April 25. Plan your Romanesco planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Union County, IN?

Union County, Indiana is in USDA Hardiness Zone 6a. The average last spring frost is April 25 and first fall frost is October 17.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Union County gardeners in Zone 6a organize planting dates, track what's growing, and never miss a planting window.

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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 Union County, IN. Local conditions may vary. Last updated: April 2026.