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When to plant Zinnia in Washington County, FL

Zinnia planted in Washington County between February 12 and March 5 matures in 70 days — well before the November 20 first frost.

When to Plant Zinnia in Washington County, FL

Washington County, Florida Zone 9a June

This month in Washington County, Florida

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

Avg. last frost March 5
Avg. first frost November 20
Soil temp (4") 83°F
Watering Low
Pest pressure High
Daylight 14 hrs
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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.

Washington County, Florida is in USDA Zone 9a. The average last spring frost is March 5 and the first fall frost is November 20, giving you a growing season of approximately 260 days.

At an elevation of 196 feet, Washington County receives approximately 50.6 inches of rainfall annually with predominantly sand soil. Summer highs average 97°F, so Zinnia may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Zinnia will need more frequent watering and organic matter to retain nutrients. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Zinnia root diseases.

Annual Blooms in Summer Pollinator-friendly Deer-resistant Good for cutting
Washington County, FL (Zone 9a) Long season
260 days
Last Spring Frost March 5
260 growing days
First Fall Frost November 20

Washington County Soil Profile

Soil Type

Sand

Soil pH

4.8-5.9

Drainage

Well Drained

Zinnia Planting Risk Windows

Early Start (70% safe) ✓ Fits season (45 days to spare)
Start indoors: Jan 26 Transplant: Feb 2 🌸 Bloom: Apr 13 – Sep 28
Recommended (50%) ✓ Fits season (43 days to spare)
Start indoors: Feb 5 Transplant: Feb 12 🌸 Bloom: Apr 23 – Oct 8
Safe Start (90%) ✓ Fits season (43 days to spare)
Start indoors: Feb 27 Transplant: Mar 6 🌸 Bloom: May 15 – Oct 30

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 Washington County

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

Soil pH

Your soil pH (4.8–5.9) is more acidic than Zinnia prefers (5.5–7.5). Add garden lime to raise pH.

Soil Texture

Sandy soil in Washington County warms quickly in spring but drains fast. Zinnia will need more frequent watering and regular compost additions to retain nutrients.

Drainage

Drainage is adequate for Zinnia.

Organic Matter

Organic matter is low (1.7%). Add 2-3 inches of compost before planting Zinnia.

How to Plant Zinnia

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

Succession Planting Zinnia

5
successive plantings in your 260-day season

Sow every 6.9 weeks. Last sowing by Sep 11 to harvest before frost.

Zinnia Water Budget

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

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 2" 0" ❄️ Dormant
Feb 2.8" 0" ❄️ Dormant
Mar 2.2" 2.5" 0" ✅ Rainfall sufficient
Apr 2.2" 2.2" 0" ✅ Rainfall sufficient
May 2.2" 3.7" 0" ✅ Rainfall sufficient
Jun 2.2" 6.8" 0" ✅ Rainfall sufficient
Jul 2.2" 8.5" 0" ✅ Rainfall sufficient
Aug 2.2" 6.5" 0" ✅ Rainfall sufficient
Sep 2.2" 7.3" 0" ✅ Rainfall sufficient
Oct 2.2" 4" 0" ✅ Rainfall sufficient
Nov 2.2" 2.1" 0.1" 💧 Light watering
Dec 2.2" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Washington 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 ~1,479 GDD — county provides 5,915 GDD Excellent fit

Zinnia Planting Timeline — Washington County, FL

Zinnia Planting Calendar

Activity When Date Range
Start Indoors February 5 Feb 5 – Feb 19
Transplant Outdoors February 12 Feb 12 – Feb 26
Direct Sow February 12 Feb 12 – Mar 5
Bloom April 23 Apr 23 – Oct 8

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

Month-by-Month Timeline

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

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: too_acidic

🗺️ USDA Zone

Zone 9a

📆 Growing Season

260 days in Washington County

Growing Tips for Zinnia in Washington County

Direct sow Zinnia outdoors after March 05 in Washington County when soil has warmed and frost danger has passed.

Sandy soil in Washington County dries quickly — mulch Zinnia with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

With summer highs reaching 97°F in Washington County, provide afternoon shade for Zinnia and water deeply in the morning.

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

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 Washington County, FL?

Washington County is in Zone 9a with an average last frost of March 5. Plan your Zinnia planting based on this frost date — see the calendar above for exact timing.

What planting zone is Washington County, FL?

Washington County, Florida is in USDA Hardiness Zone 9a. The average last spring frost is March 5 and first fall frost is November 20.

When should I plant Zinnia in Washington County, FL?

In Washington County, FL, plant Zinnia after the last frost (around March 5) and before the first frost (around November 20). Best results when soil holds above 50°F.

What growing zone is Washington County, FL for Zinnia?

Washington County sits in USDA Zone 9a. Zinnia grows reliably in zones 3a through 11b, so it's a good fit here.

Can Zinnia grow in Washington County's climate?

Yes — Zinnia grows well in Washington County's temperate climate. Washington County averages a 260-day frost-free season, with last frost around March 5 and first frost around November 20.

🌱

Your Washington County Garden Planner — Free

A 22-page printable planner built for Washington County (Zone 9a). 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 Washington County, FL. Local conditions may vary. Last updated: June 2026.

Sources & credits

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