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When to Plant Borage in Yuma County, AZ

Yuma County, Arizona Zone 10a May

May to-do list for Yuma County, Arizona

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

Avg. last frost February 10
Avg. first frost December 1
Soil temp (4") 66°F
Watering Critical
Pest pressure High
Daylight 13.7 hrs
  1. Pick borage

    Check every 1–2 days. Many of these get tough or go to seed if you wait too long.

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Borage is a self-seeding annual herb with star-shaped blue flowers that attract pollinators. Its leaves have a cucumber-like flavor and the flowers are edible.

Yuma County, Arizona is in USDA Zone 10a. The average last spring frost is February 10 and the first fall frost is December 1, giving you a growing season of approximately 294 days.

At an elevation of 4,781 feet, Yuma County receives approximately 9.4 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 92°F, providing good warmth for Borage during the growing season. Sandy soil warms quickly in spring — great for early planting — but Borage will need more frequent watering and organic matter to retain nutrients. With low rainfall, drip irrigation is essential for growing Borage successfully. Mulch heavily to conserve soil moisture.

Yuma County, AZ (Zone 10a) Year-round
294 days
Last Spring Frost February 10
294 growing days
First Fall Frost December 1
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Yuma County Soil Profile

Soil Type

Sandy Loam

Soil pH

6.9-8.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (198 days to spare)
Start indoors: Jan 6 Transplant: Jan 27 🍅 Harvest: Mar 24 – May 12
Recommended (50%) ✓ Fits season (196 days to spare)
Start indoors: Jan 13 Transplant: Feb 3 🍅 Harvest: Mar 31 – May 19
Safe Start (90%) ✓ Fits season (186 days to spare)
Start indoors: Feb 9 Transplant: Mar 2 🍅 Harvest: Apr 27 – Jun 15

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 Yuma County

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

Soil pH

Your soil pH (6.9–8.4) is more alkaline than Borage prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

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

How to Plant Borage

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

Fall planting: Sow 8 weeks before your first frost date for a fall harvest.

Succession Planting Borage

7
successive plantings in your 294-day season

Sow every 5.7 weeks. Last sowing by Oct 02 to harvest before frost.

For a dedicated fall crop, sow by Oct 06.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
0.1″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 1,154 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Borage

Borage 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 Borage Needs Rainfall You Supplement Action
Jan 0.6" 0" ❄️ Dormant
Feb 2.2" 0.5" 1.7" 🚿 Regular watering
Mar 2.2" 0.5" 1.7" 🚿 Regular watering
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" 1.8" 0.4" 💧 Light watering
Aug 2.2" 1.9" 0.3" 💧 Light watering
Sep 2.2" 1.4" 0.8" 💧 Light watering
Oct 2.2" 0.8" 1.4" 🚿 Regular watering
Nov 2.2" 0.5" 1.7" 🚿 Regular watering
Dec 2.2" 0.6" 1.6" 🚿 Regular watering

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

Borage 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.

Borage needs ~1,045 GDD — county provides 5,605 GDD Excellent fit

Borage Planting Timeline — Yuma County, AZ

Borage Planting Calendar

Activity When Date Range
Start Indoors January 13 Jan 13 – Jan 27
Transplant Outdoors February 3 Feb 3 – Feb 17
Direct Sow January 20 Jan 20 – Feb 10
Harvest March 31 Mar 31 – May 19
Fall Sowing October 6 Oct 6 – Oct 20

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

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

50–60 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 10a

📆 Growing Season

294 days in Yuma County

Growing Tips for Borage in Yuma County

Direct sow Borage outdoors after February 10 in Yuma County when soil has warmed and frost danger has passed.

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

General growing tips

Direct sow in spring as borage does not transplant well. Allow some plants to go to seed for next year. Young leaves are best; older leaves become bristly.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Borage in Yuma County, AZ?

Yuma County is in Zone 10a with an average last frost of February 10. Plan your Borage planting based on this frost date — see the calendar above for exact timing.

What planting zone is Yuma County, AZ?

Yuma County, Arizona is in USDA Hardiness Zone 10a. The average last spring frost is February 10 and first fall frost is December 1.

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Your Yuma County Garden Planner — Free

A 24-page printable planner built for Yuma County (Zone 10a). 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 Yuma 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.