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When to Plant Cauliflower in Madison County, ID

Madison County, Idaho Zone 5a May

This month in Madison County, Idaho

We've pulled the most time-sensitive tasks for Madison County, Idaho this May and put them front and centre. Tackle them in order.

Avg. last frost May 31
Avg. first frost September 11
Soil temp (4") 41°F
Watering High
Pest pressure Low
Daylight 14.5 hrs
  1. Time to transplant cauliflower

    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. Outdoor sowing time: cauliflower

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

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Cauliflower is a cool-season brassica that produces dense white, purple, or green heads called curds. It is more finicky than broccoli but rewards with a mild, nutty flavor.

Madison County, Idaho is in USDA Zone 5a. The average last spring frost is May 31 and the first fall frost is September 11, giving you a growing season of approximately 103 days.

At an elevation of 6,385 feet, Madison County receives approximately 19 inches of rainfall annually with predominantly loam soil. Summer highs average 85°F, providing good warmth for Cauliflower during the growing season. With low rainfall, drip irrigation is essential for growing Cauliflower successfully. Mulch heavily to conserve soil moisture.

Madison County, ID (Zone 5a) Short season
103 days
Last Spring Frost May 31
103 growing days
First Fall Frost September 11
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Madison County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 16 Transplant: May 21 🍅 Harvest: Jul 16 – Sep 17
Recommended (50%) ✗ May not fit
Start indoors: Apr 26 Transplant: May 31 🍅 Harvest: Jul 26 – Sep 27
Safe Start (90%) ✗ May not fit
Start indoors: May 17 Transplant: Jun 21 🍅 Harvest: Aug 16 – Oct 18

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 Madison County

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

Soil pH

Your soil pH (6.2–7.8) overlaps with Cauliflower's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.3%). Annual compost additions will help Cauliflower.

How to Plant Cauliflower

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

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

Succession Planting Cauliflower

2
successive plantings in your 103-day season

Sow every 6.3 weeks. Last sowing by Jun 03 to harvest before frost.

For a dedicated fall crop, sow by Jul 03.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 248 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Cauliflower

Cauliflower needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Cauliflower Needs Rainfall You Supplement Action
Jan 1.1" 0" ❄️ Dormant
Feb 1" 0" ❄️ Dormant
Mar 1.9" 0" ❄️ Dormant
Apr 2.1" 0" ❄️ Dormant
May 4.3" 2.5" 1.8" 💧 Light watering
Jun 4.3" 1.2" 3.1" 🚿 Regular watering
Jul 4.3" 1.6" 2.7" 🚿 Regular watering
Aug 4.3" 2.2" 2.1" 💧 Light watering
Sep 4.3" 1.6" 2.7" 🚿 Regular watering
Oct 1.6" 0" ❄️ Dormant
Nov 1.3" 0" ❄️ Dormant
Dec 1" 0" ❄️ Dormant

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

Cauliflower 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.

Cauliflower needs ~1,066 GDD — county provides 1,416 GDD Excellent fit

Cauliflower Planting Timeline — Madison County, ID

Cauliflower Planting Calendar

Activity When Date Range
Start Indoors April 26 Apr 26 – May 10
Transplant Outdoors May 31 May 31 – Jun 14
Direct Sow May 17 May 17 – Jun 7
Harvest July 26 Jul 26 – Sep 27
Fall Sowing July 3 Jul 3 – Jul 17

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

55–100 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 5a

📆 Growing Season

103 days in Madison County

Growing Tips for Cauliflower in Madison County

Direct sow Cauliflower outdoors after May 31 in Madison County when soil has warmed and frost danger has passed.

Your 103.0-day growing season in Madison County is tight for Cauliflower (55.0-100.0 days to maturity). Start indoors and choose early-maturing varieties.

Common pests for Cauliflower in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

Madison County receives only 19" of rain annually. Cauliflower needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Start seeds indoors 6 weeks before transplanting. Blanch white varieties by tying outer leaves over the head. Provide consistent moisture and avoid temperature extremes.

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes
  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Cauliflower in Madison County, ID?

Madison County is in Zone 5a with an average last frost of May 31. Plan your Cauliflower planting based on this frost date — see the calendar above for exact timing.

What planting zone is Madison County, ID?

Madison County, Idaho is in USDA Hardiness Zone 5a. The average last spring frost is May 31 and first fall frost is September 11.

🌱

Your Madison County Garden Planner — Free

A 24-page printable planner built for Madison County (Zone 5a). 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 Madison 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.