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When to Plant Celery in Unity, WI

Celery
Unity, WI Zone 4b June

Your June gardening checklist

We've pulled the most time-sensitive tasks for Unity, WI this June and put them front and centre. Tackle them in order.

Avg. last frost May 11
Avg. first frost October 2
Soil temp (4") 63°F
Watering Low
Pest pressure High
Daylight 15.4 hrs
  1. Indoor seed-starting week for celery

    Label every cell. You will absolutely forget which is which otherwise.

Looking ahead to July
  • Fall sowing: celery

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Celery is a marshland plant that requires consistent moisture and cool temperatures to produce crisp, flavorful stalks. It is a rewarding but demanding garden crop.

Unity, Wisconsin is in USDA Zone 4b. The average last spring frost is May 11 and the first fall frost is October 2, giving you a growing season of approximately 144 days.

At an elevation of 723 feet, Marathon County receives approximately 39.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Celery to ensure they mature before fall.

Unity, WI (Zone 4b) Short season
144 days
Last Spring Frost May 11
144 growing days
First Fall Frost October 2

Unity Soil Profile

Soil Type

Silt Loam

Soil pH

6-7.3

Drainage

Well Drained

Celery Planting Risk Windows

Early Start (70% safe) ✓ Fits season (8 days to spare)
Start indoors: Mar 22 Transplant: May 3 🍅 Harvest: Jul 26 – Sep 20
Recommended (50%) ✓ Fits season (4 days to spare)
Start indoors: Mar 30 Transplant: May 11 🍅 Harvest: Aug 3 – Sep 28
Safe Start (90%) ✓ Fits season (7 days to spare)
Start indoors: Apr 9 Transplant: May 21 🍅 Harvest: Aug 13 – Oct 8

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 Unity

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

Soil pH

Your soil pH (6.0–7.3) overlaps with Celery's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.1%) — Celery will thrive.

How to Plant Celery

1"
Planting Depth
15"
Between Plants
24"
Between Rows

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Succession Planting Celery

2
successive plantings in your 144-day season

Sow every 9.1 weeks. Last sowing by Jun 04 to harvest before frost.

For a dedicated fall crop, sow by Jul 10.

Celery Water Budget

Plant needs
1.3″/week
Rainfall provides
1.2″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 175 gal / 100 sq ft

Monthly Watering Guide for Celery

Celery needs approximately 1.3 inches of water per week (5.6" per month). Here's how your county's rainfall compares month by month.

Month Celery Needs Rainfall You Supplement Action
Jan 1.7" 0" ❄️ Dormant
Feb 2" 0" ❄️ Dormant
Mar 2.7" 0" ❄️ Dormant
Apr 4.3" 0" ❄️ Dormant
May 5.6" 5" 0.6" 💧 Light watering
Jun 5.6" 4.5" 1.1" 💧 Light watering
Jul 5.6" 4.8" 0.8" 💧 Light watering
Aug 5.6" 4.6" 1" 💧 Light watering
Sep 5.6" 3.1" 2.5" 💧 Light watering
Oct 5.6" 3" 2.6" 💧 Light watering
Nov 2.4" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

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

Celery 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.

Celery needs ~1,225 GDD — county provides 1,764 GDD Excellent fit

Celery Planting Timeline — Unity, WI

Celery Planting Calendar

Activity When Date Range
Start Indoors March 30 Mar 30 – Apr 13
Transplant Outdoors May 11 May 11 – May 25
Direct Sow May 4 May 4 – May 25
Harvest August 3 Aug 3 – Sep 28
Fall Sowing July 10 Jul 10 – Jul 24

Plant 1" deep · 15" apart · Rows 24" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.3"/week · Only during dry spells

📅 Days to Maturity

80–120 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 4b

📆 Growing Season

144 days in Marathon County

Growing Tips for Celery in Unity

Direct sow Celery outdoors after May 11 in Marathon County when soil has warmed and frost danger has passed.

Common pests for Celery 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 10-12 weeks before last frost. Keep soil consistently moist and never let it dry out. Blanch stalks by mounding soil or using collars for milder flavor.

Companion Planting

Good Companions

Avoid Planting Near

  • Carrots
  • Parsnip

Check more plant combinations with our Companion Planting Checker →

🌱

Your Marathon County Garden Planner — Free

A 22-page printable planner built for Marathon County (Zone 4b). 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 Marathon County, WI. Local conditions may vary. Last updated: June 2026.