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When to Plant Radish in Graham County, AZ

Graham County, Arizona Zone 8b May

What to do in May

If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.

Avg. last frost April 6
Avg. first frost November 5
Soil temp (4") 62°F
Watering Critical
Pest pressure Moderate
Daylight 13.7 hrs
  1. Bring in the radish

    Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.

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Radishes are one of the fastest-growing vegetables, with some varieties ready in under a month. They come in round, elongated, and large winter types.

Graham County, Arizona is in USDA Zone 8b. The average last spring frost is April 6 and the first fall frost is November 5, giving you a growing season of approximately 213 days.

At an elevation of 2,604 feet, Graham County receives approximately 8 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 98°F, so Radish may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Radish will need more frequent watering and organic matter to retain nutrients. With low rainfall, drip irrigation is essential for growing Radish successfully. Mulch heavily to conserve soil moisture.

Graham County, AZ (Zone 8b) Long season
213 days
Last Spring Frost April 6
213 growing days
First Fall Frost November 5
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Graham County Soil Profile

Soil Type

Sandy Loam

Soil pH

7-8.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (179 days to spare)
Transplant: Mar 14 🍅 Harvest: Apr 11 – May 2
Recommended (50%) ✓ Fits season (164 days to spare)
Transplant: Apr 6 🍅 Harvest: May 4 – May 25
Safe Start (90%) ✓ Fits season (168 days to spare)
Transplant: Apr 30 🍅 Harvest: May 28 – Jun 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 Graham County

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

Soil pH

Your soil pH (7.0–8.8) is more alkaline than Radish prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Drainage

Drainage is adequate for Radish.

Organic Matter

Organic matter is low (0.8%). Add 2-3 inches of compost before planting Radish.

How to Plant Radish

0.5"
Planting Depth
2"
Between Plants
6"
Between Rows

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

Succession Planting Radish

12
successive plantings in your 213-day season

Sow every 2.4 weeks. Last sowing by Oct 01 to harvest before frost.

For a dedicated fall crop, sow by Aug 27.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
0.2″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 1,120 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Radish

Radish 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 Radish Needs Rainfall You Supplement Action
Jan 0.5" 0" ❄️ Dormant
Feb 0.5" 0" ❄️ Dormant
Mar 0.5" 0" ❄️ Dormant
Apr 2.2" 0.3" 1.9" 🚿 Regular watering
May 2.2" 0.2" 2" 🚿 Regular watering
Jun 2.2" 0.3" 1.9" 🚿 Regular watering
Jul 2.2" 1.2" 1" 💧 Light watering
Aug 2.2" 1.8" 0.4" 💧 Light watering
Sep 2.2" 1" 1.2" 🚿 Regular watering
Oct 2.2" 0.8" 1.4" 🚿 Regular watering
Nov 2.2" 0.5" 1.7" 🚿 Regular watering
Dec 0.5" 0" ❄️ Dormant

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

Radish 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.

Radish needs ~670 GDD — county provides 5,005 GDD Excellent fit

Radish Planting Timeline — Graham County, AZ

Radish Planting Calendar

Activity When Date Range
Direct Sow March 23 Mar 23 – Apr 13
Harvest April 20 Apr 20 – May 11
Fall Sowing August 27 Aug 27 – Sep 10

Plant 0.5" deep · 2" apart · Rows 6" apart

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · 1-2 times/week

📅 Days to Maturity

22–35 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 8b

📆 Growing Season

213 days in Graham County

Growing Tips for Radish in Graham County

Direct sow Radish outdoors after April 06 in Graham County when soil has warmed and frost danger has passed.

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

Summer highs in Graham County reach 98°F — grow Radish as a spring or fall crop. Use shade cloth if planting in summer.

Your generous 213.0-day season in Graham County allows multiple plantings of Radish. Sow every 11.0 days for continuous harvest.

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

General growing tips

Direct sow every 1-2 weeks for continuous harvest. Do not transplant. Harvest spring radishes promptly to prevent them from becoming pithy and hot.

Companion Planting

Good Companions

Avoid Planting Near

  • Hyssop

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Radish in Graham County, AZ?

Graham County is in Zone 8b with an average last frost of April 6. Plan your Radish planting based on this frost date — see the calendar above for exact timing.

What planting zone is Graham County, AZ?

Graham County, Arizona is in USDA Hardiness Zone 8b. The average last spring frost is April 6 and first fall frost is November 5.

🌱

Your Graham County Garden Planner — Free

A 24-page printable planner built for Graham County (Zone 8b). 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 Graham County, AZ. 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.