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When to Plant Rosemary in Utah County, UT

Utah County, Utah Zone 7a May

Your May game plan for Utah County, Utah

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

Avg. last frost May 5
Avg. first frost October 11
Soil temp (4") 46°F
Watering High
Pest pressure Low
Daylight 14.2 hrs
  1. Time to transplant rosemary

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

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Rosemary is an aromatic evergreen shrub with needle-like leaves and a piney, citrus flavor. It is a Mediterranean herb that thrives in warm, dry conditions.

Utah County, Utah is in USDA Zone 7a. The average last spring frost is May 5 and the first fall frost is October 11, giving you a growing season of approximately 159 days.

At an elevation of 5,535 feet, Utah County receives approximately 22.1 inches of rainfall annually with predominantly loam soil. Summer highs average 86°F, providing good warmth for Rosemary during the growing season.

Utah County, UT (Zone 7a) Moderate season
159 days
Last Spring Frost May 5
159 growing days
First Fall Frost October 11
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Utah County Soil Profile

Soil Type

Loam

Soil pH

6.5-8.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 3 🍅 Harvest: Jul 26 – Dec 13
Recommended (50%) ✗ May not fit
Transplant: May 12 🍅 Harvest: Aug 4 – Dec 22
Safe Start (90%) ✓ Fits season (283 days to spare)
Transplant: Jun 7 🍅 Harvest: Aug 30 – Jan 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 Utah County

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

Soil pH

Your soil pH (6.5–8.3) overlaps with Rosemary's range (6.0–7.5), though not a perfect match.

Soil Texture

The loam soil in Utah County is excellent for Rosemary — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.3%). Annual compost additions will help Rosemary.

How to Plant Rosemary

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

Succession Planting Rosemary

2
successive plantings in your 159-day season

Sow every 9.1 weeks. Last sowing by Apr 14 to harvest before frost.

Plant Water Budget

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

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Rosemary

Rosemary needs approximately 0.3 inches of water per week (1.3" per month). Here's how your county's rainfall compares month by month.

Month Rosemary Needs Rainfall You Supplement Action
Jan 1.6" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 2.2" 0" ❄️ Dormant
Apr 2.4" 0" ❄️ Dormant
May 1.3" 2.5" 0" ✅ Rainfall sufficient
Jun 1.3" 1.4" 0" ✅ Rainfall sufficient
Jul 1.3" 1.8" 0" ✅ Rainfall sufficient
Aug 1.3" 2.4" 0" ✅ Rainfall sufficient
Sep 1.3" 2.1" 0" ✅ Rainfall sufficient
Oct 1.3" 1.7" 0" ✅ Rainfall sufficient
Nov 1.4" 0" ❄️ Dormant
Dec 1.2" 0" ❄️ Dormant

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

Rosemary 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.

Rosemary needs ~1,885 GDD — county provides 2,305 GDD Good fit

Rosemary Planting Timeline — Utah County, UT

Rosemary Planting Calendar

Activity When Date Range
Transplant Outdoors May 12 May 12 – May 26
Harvest August 4 Aug 4 – Dec 22

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

Month-by-Month Timeline

MonthActivities
January
February
March
April
May Transplant Outdoors
June
July
August Harvest
September Harvest
October Harvest
November Harvest
December Harvest
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.3"/week · Natural rainfall sufficient

📅 Days to Maturity

80–180 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 7a

📆 Growing Season

159 days in Utah County

Growing Tips for Rosemary in Utah County

Direct sow Rosemary outdoors after May 05 in Utah County when soil has warmed and frost danger has passed.

Your 159.0-day growing season in Utah County is tight for Rosemary (80.0-180.0 days to maturity). Start indoors and choose early-maturing varieties.

General growing tips

Grow in well-drained soil and avoid overwatering. In cold climates, grow in containers and bring indoors for winter. Propagate from stem cuttings for faster results than seed.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Rosemary in Utah County, UT?

Utah County is in Zone 7a with an average last frost of May 5. Plan your Rosemary planting based on this frost date — see the calendar above for exact timing.

What planting zone is Utah County, UT?

Utah County, Utah is in USDA Hardiness Zone 7a. The average last spring frost is May 5 and first fall frost is October 11.

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Your Utah County Garden Planner — Free

A 24-page printable planner built for Utah County (Zone 7a). 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 Utah 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.