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When to Plant Celery in Rio Grande County, CO

Celery is a marshland plant that requires consistent moisture and cool temperatures to produce crisp, flavorful stalks. It is a rewarding but demanding garden crop.

Rio Grande County, Colorado is in USDA Zone 4b. The average last spring frost is May 31 and the first fall frost is September 19, giving you a growing season of approximately 111 days.

At an elevation of 6,254 feet, Rio Grande County receives approximately 15.8 inches of rainfall annually with predominantly loam soil. Summer highs average 80ยฐF, so choose short-season varieties of Celery to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Celery successfully. Mulch heavily to conserve soil moisture.

Rio Grande County, CO (Zone 4b) Short season
111 days
Last Spring Frost May 31
111 growing days
First Fall Frost September 19

Rio Grande County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 14 Transplant: May 26 🍅 Harvest: Aug 18 – Oct 13
Recommended (50%) ✗ May not fit
Start indoors: Apr 19 Transplant: May 31 🍅 Harvest: Aug 23 – Oct 18
Safe Start (90%) ✗ May not fit
Start indoors: May 3 Transplant: Jun 14 🍅 Harvest: Sep 6 – Nov 1

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
1.5″/week
Rainfall provides
0.6″/week
You supply
1.6″/week
Watering frequency 2-3 times/week
Season total 1,603 gal / 100 sq ft
Drought risk

Water stress score is 8/10 โ€” consider drought-tolerant varieties and mulching

Celery needs ~1,000 GDD — county provides 1,110 GDD Good fit

Celery Planting Timeline โ€” Rio Grande County, CO

Celery Planting Calendar

Activity When Date Range
Start Indoors April 19 Apr 19 โ€“ May 3
Transplant Outdoors May 31 May 31 โ€“ Jun 14
Direct Sow May 24 May 24 โ€“ Jun 14
Fall Sowing June 27 Jun 27 โ€“ Jul 11
Harvest August 23 Aug 23 โ€“ Oct 18

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

High โ€” keep soil consistently moist

Days to Maturity

80โ€“120 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 4b

Growing Season

111 days

Growing Tips for Rio Grande County

Start seeds indoors 10-12 weeks before last frost. Keep soil consistently moist and never let it dry out. Blanch stalks by mounding soil or using collars for milder flavor.

Companion Planting

Good Companions

Avoid Planting Near

  • Carrots
  • Parsnip

Level Up Your Garden

Frequently Asked Questions

When should I plant Celery in Rio Grande County, CO?

Rio Grande County is in Zone 4b with an average last frost of May 31. Plan your Celery planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Rio Grande County, CO?

Rio Grande County, Colorado is in USDA Hardiness Zone 4b. The average last spring frost is May 31 and first fall frost is September 19.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Rio Grande County gardeners in Zone 4b 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 Rio Grande County, CO. Local conditions may vary. Last updated: April 2026.