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When to Plant Cilantro in Box Elder County, UT

Box Elder County, Utah Zone 6b May

This month in Box Elder County, Utah

We've pulled the most time-sensitive tasks for Box Elder County, Utah this May and put them front and centre. Tackle them in order.

Avg. last frost May 22
Avg. first frost October 3
Soil temp (4") 50°F
Watering High
Pest pressure Low
Daylight 14.3 hrs
  1. Move cilantro from tray to bed

    Water the tray well an hour before you transplant. Roots slide out cleanly and settle in faster.

  2. Scatter cilantro into prepared beds

    Mark the row. Birds and stray feet both have opinions about unmarked beds.

Get ahead of June
  • Starting indoors: cilantro
  • First harvests: cilantro

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Cilantro is a dual-purpose herb providing fresh leaves (cilantro) and dried seeds (coriander). It bolts quickly in heat, producing flowers beloved by beneficial insects.

Box Elder County, Utah is in USDA Zone 6b. The average last spring frost is May 22 and the first fall frost is October 3, giving you a growing season of approximately 134 days.

At an elevation of 4,039 feet, Box Elder County receives approximately 24.5 inches of rainfall annually with predominantly loam soil. Summer highs average 87°F, providing good warmth for Cilantro during the growing season.

Box Elder County, UT (Zone 6b) Short season
134 days
Last Spring Frost May 22
134 growing days
First Fall Frost October 3
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Box Elder County Soil Profile

Soil Type

Loam

Soil pH

6.3-7.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (37 days to spare)
Start indoors: Apr 7 Transplant: May 5 🍅 Harvest: Jun 16 – Aug 18
Recommended (50%) ✓ Fits season (36 days to spare)
Start indoors: Apr 17 Transplant: May 15 🍅 Harvest: Jun 26 – Aug 28
Safe Start (90%) ✓ Fits season (38 days to spare)
Start indoors: May 6 Transplant: Jun 3 🍅 Harvest: Jul 15 – Sep 16

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 Box Elder County

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

Soil pH

Your soil pH (6.3–7.9) is more alkaline than Cilantro prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Box Elder County is excellent for Cilantro — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.7%). Annual compost additions will help Cilantro.

How to Plant Cilantro

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

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

Succession Planting Cilantro

3
successive plantings in your 134-day season

Sow every 4.6 weeks. Last sowing by Aug 04 to harvest before frost.

For a dedicated fall crop, sow by Jul 25.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
0.8″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Cilantro

Cilantro needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.

Month Cilantro Needs Rainfall You Supplement Action
Jan 1.5" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 1.9" 0" ❄️ Dormant
Apr 2.7" 0" ❄️ Dormant
May 2.2" 2.4" 0" ✅ Rainfall sufficient
Jun 2.2" 1.7" 0.5" 💧 Light watering
Jul 2.2" 2.4" 0" ✅ Rainfall sufficient
Aug 2.2" 2.8" 0" ✅ Rainfall sufficient
Sep 2.2" 1.8" 0.4" 💧 Light watering
Oct 2.2" 2.4" 0" ✅ Rainfall sufficient
Nov 1.7" 0" ❄️ Dormant
Dec 1.6" 0" ❄️ Dormant

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

Cilantro 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.

Cilantro needs ~762 GDD — county provides 2,043 GDD Excellent fit

Cilantro Planting Timeline — Box Elder County, UT

Cilantro Planting Calendar

Activity When Date Range
Start Indoors April 17 Apr 17 – May 1
Transplant Outdoors May 15 May 15 – May 29
Direct Sow May 8 May 8 – May 29
Harvest June 26 Jun 26 – Aug 28
Fall Sowing July 25 Jul 25 – Aug 8

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

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

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

40–60 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 6b

📆 Growing Season

134 days in Box Elder County

Growing Tips for Cilantro in Box Elder County

Direct sow Cilantro outdoors after May 22 in Box Elder County when soil has warmed and frost danger has passed.

Common pests for Cilantro in this region include carrot rust fly and parsleyworm. Use row covers early in the season and inspect plants weekly.

General growing tips

Succession sow every 2-3 weeks. Provide afternoon shade in warm weather. Harvest leaves before flowering or allow some plants to go to seed for coriander and self-sowing.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Cilantro in Box Elder County, UT?

Box Elder County is in Zone 6b with an average last frost of May 22. Plan your Cilantro planting based on this frost date — see the calendar above for exact timing.

What planting zone is Box Elder County, UT?

Box Elder County, Utah is in USDA Hardiness Zone 6b. The average last spring frost is May 22 and first fall frost is October 3.

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Your Box Elder County Garden Planner — Free

A 24-page printable planner built for Box Elder 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.

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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 Box Elder County, UT. 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.