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When to Plant Amaranth in Merced County, CA

Merced County, California Zone 9a May

Your May game plan for Merced County, California

A quick May briefing for Merced County, California gardeners — what's urgent, what's next, and what can wait.

Avg. last frost February 24
Avg. first frost November 28
Soil temp (4") 74°F
Watering Critical
Pest pressure High
Daylight 14 hrs
Coming up in June — start thinking about
  • First harvests: amaranth

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Amaranth is an ancient grain crop with edible leaves and seeds, rich in protein and micronutrients. It thrives in warm conditions and is drought-tolerant once established.

Merced County, California is in USDA Zone 9a. The average last spring frost is February 24 and the first fall frost is November 28, giving you a growing season of approximately 277 days.

At an elevation of 269 feet, Merced County receives approximately 18.8 inches of rainfall annually with predominantly loam soil. Summer highs average 87°F, providing good warmth for Amaranth during the growing season. With low rainfall, drip irrigation is essential for growing Amaranth successfully. Mulch heavily to conserve soil moisture.

Merced County, CA (Zone 9a) Year-round
277 days
Last Spring Frost February 24
277 growing days
First Fall Frost November 28

Merced County Soil Profile

Soil Type

Loam

Soil pH

6.8-7.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (142 days to spare)
Start indoors: Dec 26 Transplant: Feb 13 🍅 Harvest: May 15 – Jul 3
Recommended (50%) ✓ Fits season (130 days to spare)
Start indoors: Jan 13 Transplant: Mar 3 🍅 Harvest: Jun 2 – Jul 21
Safe Start (90%) ✓ Fits season (95 days to spare)
Start indoors: Mar 7 Transplant: Apr 25 🍅 Harvest: Jul 25 – Sep 12

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 Merced County

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

Soil pH

Your soil pH (6.8–7.7) overlaps with Amaranth's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.6%). Annual compost additions will help Amaranth.

How to Plant Amaranth

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

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.3″/week
You supply
0.9″/week
Watering frequency 2-3 times/week
Season total 2,126 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Amaranth

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

Month Amaranth Needs Rainfall You Supplement Action
Jan 4.4" 0" ❄️ Dormant
Feb 4.3" 4" 0.3" 💧 Light watering
Mar 4.3" 2.6" 1.7" 💧 Light watering
Apr 4.3" 1.7" 2.6" 🚿 Regular watering
May 4.3" 0.4" 3.9" 🚿 Regular watering
Jun 4.3" 0.1" 4.2" 🚿 Regular watering
Jul 4.3" 0" 4.3" 🚿 Regular watering
Aug 4.3" 0" 4.3" 🚿 Regular watering
Sep 4.3" 0.2" 4.1" 🚿 Regular watering
Oct 4.3" 0.7" 3.6" 🚿 Regular watering
Nov 4.3" 1.6" 2.7" 🚿 Regular watering
Dec 3.1" 0" ❄️ Dormant

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

Amaranth 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.

Amaranth needs ~1,601 GDD — county provides 4,239 GDD Excellent fit

Amaranth Planting Timeline — Merced County, CA

Amaranth Planting Calendar

Activity When Date Range
Start Indoors January 13 Jan 13 – Jan 27
Transplant Outdoors March 3 Mar 3 – Mar 17
Direct Sow February 24 Feb 24 – Mar 17
Harvest June 2 Jun 2 – Jul 21

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 2-3 times/week

📅 Days to Maturity

90–120 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 9a

📆 Growing Season

277 days in Merced County

Growing Tips for Amaranth in Merced County

Direct sow Amaranth outdoors after February 24 in Merced County when soil has warmed and frost danger has passed.

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

General growing tips

Direct sow after last frost when soil is warm. Thin seedlings to 18 inches apart. Harvest leaves when young and tender; harvest seeds when flower heads begin to dry.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Amaranth in Merced County, CA?

Merced County is in Zone 9a with an average last frost of February 24. Plan your Amaranth planting based on this frost date — see the calendar above for exact timing.

What planting zone is Merced County, CA?

Merced County, California is in USDA Hardiness Zone 9a. The average last spring frost is February 24 and first fall frost is November 28.

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Your Merced County Garden Planner — Free

A 24-page printable planner built for Merced County (Zone 9a). 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 Merced County, CA. 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.