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When to Plant Zinnia in Crook County, OR

Crook County, Oregon Zone 6a July

Your July game plan for Crook County, Oregon

Each item below is timed to Crook County, Oregon's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost June 9
Avg. first frost September 19
Soil temp (4") 75°F
Watering Critical
Pest pressure High
Daylight 15 hrs
  1. Get zinnia seeds going inside

    Bottom-water once the first true leaves appear — it keeps stems dry and knocks back damping-off.

Coming up in August — start thinking about
  • First harvests: zinnia

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Zinnia (Zinnia elegans) is a fast-growing, heat-loving annual that produces bold, dahlia-like blooms from early summer until hard frost. One of the easiest flowers to grow from direct-sown seed, zinnias thrive in hot, dry conditions and are magnets for butterflies and beneficial insects. They make excellent companion plants alongside marigolds in the vegetable garden.

Crook County, Oregon is in USDA Zone 6a. The average last spring frost is June 9 and the first fall frost is September 19, giving you a growing season of approximately 102 days.

At an elevation of 2,233 feet, Crook County receives approximately 21 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Zinnia during the growing season.

Annual Blooms in Summer Pollinator-friendly Deer-resistant Good for cutting
Crook County, OR (Zone 6a) Short season
102 days
Last Spring Frost June 9
102 growing days
First Fall Frost September 19

Crook County Soil Profile

Soil Type

Silt Loam

Soil pH

5.7-6.7

Drainage

Well Drained

Zinnia Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: May 2 Transplant: Jun 6 🌸 Bloom: Aug 15 – Nov 21
Recommended (50%) ✗ May not fit
Start indoors: May 12 Transplant: Jun 16 🌸 Bloom: Aug 25 – Dec 1
Safe Start (90%) ✗ May not fit
Start indoors: May 25 Transplant: Jun 29 🌸 Bloom: Sep 7 – Dec 14

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 Crook County

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

Soil pH

Your soil pH (5.7–6.7) is within Zinnia's preferred range (5.5–7.5).

Soil Texture

The silt loam soil in Crook County is excellent for Zinnia — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (5.6%) — Zinnia will thrive.

How to Plant Zinnia

0.3"
Planting Depth
12"
Between Plants
18"
Between Rows

Zinnia 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 Zinnia

Zinnia 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 Zinnia Needs Rainfall You Supplement Action
Jan 3.4" 0" ❄️ Dormant
Feb 2.2" 0" ❄️ Dormant
Mar 2.2" 0" ❄️ Dormant
Apr 1.5" 0" ❄️ Dormant
May 1.2" 0" ❄️ Dormant
Jun 2.2" 0.9" 1.3" 🚿 Regular watering
Jul 2.2" 0.3" 1.9" 🚿 Regular watering
Aug 2.2" 0.4" 1.8" 🚿 Regular watering
Sep 2.2" 1" 1.2" 🚿 Regular watering
Oct 1.6" 0" ❄️ Dormant
Nov 3.1" 0" ❄️ Dormant
Dec 3.1" 0" ❄️ Dormant

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

Zinnia 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.

Zinnia needs ~894 GDD — county provides 1,402 GDD Excellent fit

Zinnia Planting Timeline — Crook County, OR

Zinnia Planting Calendar

Activity When Date Range
Start Indoors May 12 May 12 – May 26
Transplant Outdoors June 16 Jun 16 – Jun 30
Direct Sow June 16 Jun 16 – Jul 7
Bloom August 25 Aug 25 – Dec 1

Plant 0.3" deep · 12" apart · Rows 18" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April
May Start Indoors
June Transplant Outdoors Direct Sow
July Direct Sow
August Bloom
September Bloom
October Bloom
November Bloom
December Bloom

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

60–70 days

🧪 Soil pH

Needs 5.5–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 6a

📆 Growing Season

102 days in Crook County

Growing Tips for Zinnia in Crook County

Direct sow Zinnia outdoors after June 09 in Crook County when soil has warmed and frost danger has passed.

Common pests for Zinnia in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.

Crook County receives only 21" of rain annually. Zinnia needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Direct-sow after last frost when soil reaches 60°F; seeds germinate in 5-7 days. In zones 3-5 a brief indoor start (4 weeks) is worthwhile but transplant carefully — zinnias dislike root disturbance. Deadhead frequently to extend bloom. Excellent cut flower; harvesting regularly encourages branching. Avoid overhead watering to reduce powdery mildew.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Zinnia in Crook County, OR?

Crook County is in Zone 6a with an average last frost of June 9. Plan your Zinnia planting based on this frost date — see the calendar above for exact timing.

What planting zone is Crook County, OR?

Crook County, Oregon is in USDA Hardiness Zone 6a. The average last spring frost is June 9 and first fall frost is September 19.

🌱

Your Crook County Garden Planner — Free

A 22-page printable planner built for Crook 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 Crook County, OR. Local conditions may vary. Last updated: July 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.