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When to Plant Parsley in Denver County, CO

Denver County, Colorado Zone 6a May

May to-do list for Denver County, Colorado

Your garden in Denver County, Colorado is working on a schedule, even when you're not. Here's where you should be this May.

Avg. last frost May 14
Avg. first frost September 26
Soil temp (4") 38°F
Watering High
Pest pressure Low
Daylight 14.2 hrs
  1. Get parsley in the ground

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

June will be here before you know it — start on
  • Starting indoors: parsley

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Parsley is a biennial herb available in flat-leaf (Italian) and curly varieties. It is a nutritional powerhouse rich in vitamins C and K and adds fresh flavor to countless dishes.

Denver County, Colorado is in USDA Zone 6a. The average last spring frost is May 14 and the first fall frost is September 26, giving you a growing season of approximately 135 days.

At an elevation of 6,818 feet, Denver County receives approximately 20.5 inches of rainfall annually with predominantly loam soil. Summer highs average 85°F, providing good warmth for Parsley during the growing season.

Denver County, CO (Zone 6a) Short season
135 days
Last Spring Frost May 14
135 growing days
First Fall Frost September 26
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Denver County Soil Profile

Soil Type

Loam

Soil pH

6.4-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (21 days to spare)
Start indoors: Mar 29 Transplant: Apr 26 🍅 Harvest: Jun 28 – Aug 30
Recommended (50%) ✓ Fits season (16 days to spare)
Start indoors: Apr 9 Transplant: May 7 🍅 Harvest: Jul 9 – Sep 10
Safe Start (90%) ✓ Fits season (9 days to spare)
Start indoors: May 6 Transplant: Jun 3 🍅 Harvest: Aug 5 – Oct 7

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 Denver County

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

Soil pH

Your soil pH (6.4–7.8) is more alkaline than Parsley prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.2%). Annual compost additions will help Parsley.

How to Plant Parsley

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 Parsley

2
successive plantings in your 135-day season

Sow every 6.9 weeks. Last sowing by Jul 08 to harvest before frost.

For a dedicated fall crop, sow by Jul 18.

Plant Water Budget

Plant needs
0.6″/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 Parsley

Parsley needs approximately 0.6 inches of water per week (2.6" per month). Here's how your county's rainfall compares month by month.

Month Parsley Needs Rainfall You Supplement Action
Jan 1.4" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 1.8" 0" ❄️ Dormant
Apr 2.4" 0" ❄️ Dormant
May 2.6" 2.3" 0.3" 💧 Light watering
Jun 2.6" 1.3" 1.3" 🚿 Regular watering
Jul 2.6" 1.8" 0.8" 💧 Light watering
Aug 2.6" 2.1" 0.5" 💧 Light watering
Sep 2.6" 1.8" 0.8" 💧 Light watering
Oct 1.8" 0" ❄️ Dormant
Nov 1.6" 0" ❄️ Dormant
Dec 1.2" 0" ❄️ Dormant

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

Parsley 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.

Parsley needs ~962 GDD — county provides 1,856 GDD Excellent fit

Parsley Planting Timeline — Denver County, CO

Parsley Planting Calendar

Activity When Date Range
Start Indoors April 9 Apr 9 – Apr 23
Transplant Outdoors May 7 May 7 – May 21
Direct Sow April 30 Apr 30 – May 21
Harvest July 9 Jul 9 – Sep 10
Fall Sowing July 18 Jul 18 – Aug 1

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

Month-by-Month Timeline

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

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.6"/week · Natural rainfall sufficient

📅 Days to Maturity

60–80 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 6a

📆 Growing Season

135 days in Denver County

Growing Tips for Parsley in Denver County

Direct sow Parsley outdoors after May 14 in Denver County when soil has warmed and frost danger has passed.

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

General growing tips

Start seeds indoors 6-8 weeks before last frost. Soak seeds overnight as germination is slow. Harvest outer stems first to keep plants productive. Parsley attracts swallowtail butterflies.

Companion Planting

Good Companions

Avoid Planting Near

  • Mint
  • Lettuce

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Parsley in Denver County, CO?

Denver County is in Zone 6a with an average last frost of May 14. Plan your Parsley planting based on this frost date — see the calendar above for exact timing.

What planting zone is Denver County, CO?

Denver County, Colorado is in USDA Hardiness Zone 6a. The average last spring frost is May 14 and first fall frost is September 26.

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Your Denver County Garden Planner — Free

A 24-page printable planner built for Denver County (Zone 6a). 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 Denver County, CO. 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.