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When to Plant Lemon Thyme in Palo Alto County, IA

Palo Alto County, Iowa Zone 5a May

Top priorities for Palo Alto County, Iowa gardeners in May

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

Avg. last frost April 27
Avg. first frost October 8
Soil temp (4") 54°F
Watering Low
Pest pressure Low
Daylight 14.5 hrs
  1. Plant out lemon thyme

    Frost risk is low now in Palo Alto County, Iowa. If you've been covering beds overnight, you can stop.

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Lemon thyme is a low-growing perennial herb with tiny, citrus-scented leaves. It combines the savory quality of thyme with a bright lemon flavor, excellent with fish and poultry.

Palo Alto County, Iowa is in USDA Zone 5a. The average last spring frost is April 27 and the first fall frost is October 8, giving you a growing season of approximately 164 days.

At an elevation of 1,358 feet, Palo Alto County receives approximately 34.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 81°F, so choose short-season varieties of Lemon Thyme to ensure they mature before fall.

Palo Alto County, IA (Zone 5a) Moderate season
164 days
Last Spring Frost April 27
164 growing days
First Fall Frost October 8
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Palo Alto County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (25 days to spare)
Transplant: Apr 28 🍅 Harvest: Jul 7 – Sep 8
Recommended (50%) ✓ Fits season (24 days to spare)
Transplant: May 4 🍅 Harvest: Jul 13 – Sep 14
Safe Start (90%) ✓ Fits season (25 days to spare)
Transplant: May 21 🍅 Harvest: Jul 30 – Oct 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.

Soil Compatibility in Palo Alto County

How your county's soil matches Lemon Thyme's growing requirements.

Soil pH

Your soil pH (6.1–6.9) is within Lemon Thyme's preferred range (6.0–8.0).

Soil Texture

The silt loam soil in Palo Alto County is excellent for Lemon Thyme — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (4.8%) — Lemon Thyme will thrive.

How to Plant Lemon Thyme

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

Succession Planting Lemon Thyme

2
successive plantings in your 164-day season

Sow every 8 weeks. Last sowing by Jul 10 to harvest before frost.

Plant Water Budget

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

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Lemon Thyme

Lemon Thyme 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 Lemon Thyme Needs Rainfall You Supplement Action
Jan 1.6" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2.8" 0" ❄️ Dormant
Apr 2.2" 3.5" 0" ✅ Rainfall sufficient
May 2.2" 4.4" 0" ✅ Rainfall sufficient
Jun 2.2" 4.1" 0" ✅ Rainfall sufficient
Jul 2.2" 4.1" 0" ✅ Rainfall sufficient
Aug 2.2" 3.2" 0" ✅ Rainfall sufficient
Sep 2.2" 2.8" 0" ✅ Rainfall sufficient
Oct 2.2" 2.9" 0" ✅ Rainfall sufficient
Nov 2.2" 0" ❄️ Dormant
Dec 1.8" 0" ❄️ Dormant

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

Lemon Thyme 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.

Lemon Thyme needs ~860 GDD — county provides 1,763 GDD Excellent fit

Lemon Thyme Planting Timeline — Palo Alto County, IA

Lemon Thyme Planting Calendar

Activity When Date Range
Transplant Outdoors May 4 May 4 – May 18
Harvest July 13 Jul 13 – Sep 14

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

70–90 days

🧪 Soil pH

Needs 6–8 · Your soil: ideal

🗺️ USDA Zone

Zone 5a

📆 Growing Season

164 days in Palo Alto County

Growing Tips for Lemon Thyme in Palo Alto County

Direct sow Lemon Thyme outdoors after April 27 in Palo Alto County when soil has warmed and frost danger has passed.

General growing tips

Start from cuttings or divisions. Plant in well-drained soil. Trim back after flowering. Use as a fragrant ground cover or edging plant along garden paths.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Lemon Thyme in Palo Alto County, IA?

Palo Alto County is in Zone 5a with an average last frost of April 27. Plan your Lemon Thyme planting based on this frost date — see the calendar above for exact timing.

What planting zone is Palo Alto County, IA?

Palo Alto County, Iowa is in USDA Hardiness Zone 5a. The average last spring frost is April 27 and first fall frost is October 8.

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Your Palo Alto County Garden Planner — Free

A 24-page printable planner built for Palo Alto County (Zone 5a). 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 Palo Alto County, IA. 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.