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When to Plant Dill in Douglas County, CO

Douglas County, Colorado Zone 5b May

Douglas County, Colorado gardeners: here's your May plan

If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.

Avg. last frost May 22
Avg. first frost September 20
Soil temp (4") 35°F
Watering High
Pest pressure Low
Daylight 14.2 hrs
  1. Get dill in the ground

    Plant tomatoes deep — bury the stem up to the first true leaves to grow extra roots. Everything else goes in at the same depth it grew in the tray.

  2. Direct-sow dill

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

Coming up in June — start thinking about
  • Starting indoors: dill
  • First harvests: dill

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Dill is a feathery annual herb with aromatic leaves and seeds. Its fine foliage and umbrella-shaped flower heads attract beneficial insects to the garden.

Douglas County, Colorado is in USDA Zone 5b. The average last spring frost is May 22 and the first fall frost is September 20, giving you a growing season of approximately 121 days.

At an elevation of 7,421 feet, Douglas County receives approximately 12.9 inches of rainfall annually with predominantly loam soil. Summer highs average 85°F, providing good warmth for Dill during the growing season. With low rainfall, drip irrigation is essential for growing Dill successfully. Mulch heavily to conserve soil moisture.

Douglas County, CO (Zone 5b) Short season
121 days
Last Spring Frost May 22
121 growing days
First Fall Frost September 20
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Douglas County Soil Profile

Soil Type

Loam

Soil pH

6.7-8.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (24 days to spare)
Start indoors: Apr 7 Transplant: May 5 🍅 Harvest: Jun 16 – Aug 18
Recommended (50%) ✓ Fits season (23 days to spare)
Start indoors: Apr 17 Transplant: May 15 🍅 Harvest: Jun 26 – Aug 28
Safe Start (90%) ✓ Fits season (19 days to spare)
Start indoors: May 15 Transplant: Jun 12 🍅 Harvest: Jul 24 – Sep 25

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 Douglas County

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

Soil pH

Your soil pH (6.7–8.4) is more alkaline than Dill prefers (5.5–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.6%). Annual compost additions will help Dill.

How to Plant Dill

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 Dill

3
successive plantings in your 121-day season

Sow every 4.6 weeks. Last sowing by Jul 22 to harvest before frost.

For a dedicated fall crop, sow by Jul 12.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
0.5″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 67 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Dill

Dill 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 Dill Needs Rainfall You Supplement Action
Jan 1" 0" ❄️ Dormant
Feb 0.8" 0" ❄️ Dormant
Mar 1.1" 0" ❄️ Dormant
Apr 1.3" 0" ❄️ Dormant
May 2.2" 1.4" 0.8" 💧 Light watering
Jun 2.2" 1" 1.2" 🚿 Regular watering
Jul 2.2" 1" 1.2" 🚿 Regular watering
Aug 2.2" 1.4" 0.8" 💧 Light watering
Sep 2.2" 1.1" 1.1" 🚿 Regular watering
Oct 1.1" 0" ❄️ Dormant
Nov 1" 0" ❄️ Dormant
Dec 0.8" 0" ❄️ Dormant

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

Dill 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.

Dill needs ~688 GDD — county provides 1,663 GDD Excellent fit

Dill Planting Timeline — Douglas County, CO

Dill 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 12 Jul 12 – Jul 26

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 Harvest
September
October
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Only during dry spells

📅 Days to Maturity

40–60 days

🧪 Soil pH

Needs 5.5–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 5b

📆 Growing Season

121 days in Douglas County

Growing Tips for Dill in Douglas County

Direct sow Dill outdoors after May 22 in Douglas County when soil has warmed and frost danger has passed.

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

General growing tips

Direct sow in spring as dill has a taproot and dislikes transplanting. Succession sow for continuous leaf harvest. Allow some plants to flower for seeds and to attract beneficial insects.

Companion Planting

Good Companions

Avoid Planting Near

  • Carrots
  • Tomatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Dill in Douglas County, CO?

Douglas County is in Zone 5b with an average last frost of May 22. Plan your Dill planting based on this frost date — see the calendar above for exact timing.

What planting zone is Douglas County, CO?

Douglas County, Colorado is in USDA Hardiness Zone 5b. The average last spring frost is May 22 and first fall frost is September 20.

🌱

Your Douglas County Garden Planner — Free

A 24-page printable planner built for Douglas County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Douglas 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.