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When to Plant Celery in Adams County, ID

Adams County, Idaho Zone 6a May

May in Adams County, Idaho — your action list

May is a pivotal month for Adams County, Idaho gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost May 20
Avg. first frost September 25
Soil temp (4") 39°F
Watering High
Pest pressure Low
Daylight 14.6 hrs
  1. Get celery in the ground

    Bring a watering can to the bed. Each transplant gets a drink the moment it's in the ground, not ten minutes later.

  2. Scatter celery into prepared beds

    Succession planting is the secret here. Put in a row now, another in 2 weeks, a third in 4.

Before June arrives, get these ready
  • Starting indoors: 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.

Adams County, Idaho is in USDA Zone 6a. The average last spring frost is May 20 and the first fall frost is September 25, giving you a growing season of approximately 128 days.

At an elevation of 6,593 feet, Adams County receives approximately 20.6 inches of rainfall annually with predominantly loam soil. Summer highs average 85°F, providing good warmth for Celery during the growing season.

Adams County, ID (Zone 6a) Short season
128 days
Last Spring Frost May 20
128 growing days
First Fall Frost September 25
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Adams County Soil Profile

Soil Type

Loam

Soil pH

6.3-8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 31 Transplant: May 5 🍅 Harvest: Jul 28 – Sep 22
Recommended (50%) ✗ May not fit
Start indoors: Apr 15 Transplant: May 20 🍅 Harvest: Aug 12 – Oct 7
Safe Start (90%) ✗ May not fit
Start indoors: May 19 Transplant: Jun 23 🍅 Harvest: Sep 15 – Nov 10

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 Adams County

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

Soil pH

Your soil pH (6.3–8.0) is more alkaline than Celery prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Drainage

Celery is a heavy drinker but your soil drains very quickly. Mulch heavily and consider drip irrigation.

Organic Matter

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

How to Plant Celery

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

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Plant Water Budget

Plant needs
1.3″/week
Rainfall provides
0.7″/week
You supply
1.2″/week
Watering frequency 2-3 times/week
Season total 1,386 gal / 100 sq ft
Drought risk

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

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 1.4" 0" ❄️ Dormant
Feb 1.1" 0" ❄️ Dormant
Mar 1.9" 0" ❄️ Dormant
Apr 2" 0" ❄️ Dormant
May 5.6" 2.6" 3" 🚿 Regular watering
Jun 5.6" 1.4" 4.2" 🚿 Regular watering
Jul 5.6" 2" 3.6" 🚿 Regular watering
Aug 5.6" 2.1" 3.5" 🚿 Regular watering
Sep 5.6" 1.7" 3.9" 🚿 Regular watering
Oct 1.8" 0" ❄️ Dormant
Nov 1.4" 0" ❄️ Dormant
Dec 1.2" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Adams 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 ~1,375 GDD — county provides 1,760 GDD Good fit

Celery Planting Timeline — Adams County, ID

Celery Planting Calendar

Activity When Date Range
Start Indoors April 15 Apr 15 – Apr 29
Transplant Outdoors May 20 May 20 – Jun 3
Direct Sow May 6 May 6 – May 27
Harvest August 12 Aug 12 – Oct 7
Fall Sowing July 17 Jul 17 – Jul 31

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.3"/week · 2-3 times/week

📅 Days to Maturity

80–120 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 6a

📆 Growing Season

128 days in Adams County

Growing Tips for Celery in Adams County

Direct sow Celery outdoors after May 20 in Adams County when soil has warmed and frost danger has passed.

Your 128.0-day growing season in Adams County is tight for Celery (80.0-120.0 days to maturity). Start indoors and choose early-maturing varieties.

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

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

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 →

Frequently Asked Questions

When should I plant Celery in Adams County, ID?

Adams County is in Zone 6a with an average last frost of May 20. Plan your Celery planting based on this frost date — see the calendar above for exact timing.

What planting zone is Adams County, ID?

Adams County, Idaho is in USDA Hardiness Zone 6a. The average last spring frost is May 20 and first fall frost is September 25.

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Your Adams County Garden Planner — Free

A 24-page printable planner built for Adams 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 Adams County, ID. 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.