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When to Plant New Zealand Spinach in Humboldt County, CA

Humboldt County, California Zone 9b May

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Avg. last frost February 27
Avg. first frost November 28
Soil temp (4") 74°F
Watering Critical
Pest pressure High
Daylight 14.3 hrs
  1. Start harvesting new zealand spinach

    If you can't use it all right away, check the food-preservation section of your planner.

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New Zealand spinach is a heat-tolerant ground-cover plant with thick, triangular leaves that taste similar to true spinach. It thrives in hot weather when regular spinach bolts.

Humboldt County, California is in USDA Zone 9b. The average last spring frost is February 27 and the first fall frost is November 28, giving you a growing season of approximately 274 days.

At an elevation of 148 feet, Humboldt County receives approximately 22.1 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 87°F, providing good warmth for New Zealand Spinach during the growing season. Sandy soil warms quickly in spring — great for early planting — but New Zealand Spinach will need more frequent watering and organic matter to retain nutrients.

Humboldt County, CA (Zone 9b) Year-round
274 days
Last Spring Frost February 27
274 growing days
First Fall Frost November 28
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Humboldt County Soil Profile

Soil Type

Sandy Loam

Soil pH

6.2-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (192 days to spare)
Start indoors: Jan 2 Transplant: Feb 20 🍅 Harvest: Apr 17 – May 15
Recommended (50%) ✓ Fits season (183 days to spare)
Start indoors: Jan 16 Transplant: Mar 6 🍅 Harvest: May 1 – May 29
Safe Start (90%) ✓ Fits season (169 days to spare)
Start indoors: Feb 19 Transplant: Apr 9 🍅 Harvest: Jun 4 – Jul 2

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 Humboldt County

How your county's soil matches New Zealand Spinach's growing requirements.

Soil pH

Your soil pH (6.2–6.8) is within New Zealand Spinach's preferred range (6.0–7.5).

Soil Texture

Sandy soil in Humboldt County warms quickly in spring but drains fast. New Zealand Spinach will need more frequent watering and regular compost additions to retain nutrients.

Organic Matter

Organic matter is moderate (2.3%). Annual compost additions will help New Zealand Spinach.

How to Plant New Zealand Spinach

0.5"
Planting Depth
6"
Between Plants
12"
Between Rows

Succession Planting New Zealand Spinach

5
successive plantings in your 274-day season

Sow every 6.3 weeks. Last sowing by Sep 19 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.3″/week
You supply
0.7″/week
Watering frequency 1-2 times/week
Season total 1,621 gal / 100 sq ft

Monthly Watering Guide for New Zealand Spinach

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

Month New Zealand Spinach Needs Rainfall You Supplement Action
Jan 4.8" 0" ❄️ Dormant
Feb 4.3" 5" 0" ✅ Rainfall sufficient
Mar 4.3" 3.3" 1" 💧 Light watering
Apr 4.3" 1.7" 2.6" 🚿 Regular watering
May 4.3" 0.5" 3.8" 🚿 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" 0.3" 4" 🚿 Regular watering
Oct 4.3" 0.8" 3.5" 🚿 Regular watering
Nov 4.3" 1.9" 2.4" 🚿 Regular watering
Dec 3.7" 0" ❄️ Dormant

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

New Zealand Spinach 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.

New Zealand Spinach needs ~953 GDD — county provides 4,193 GDD Excellent fit

New Zealand Spinach Planting Timeline — Humboldt County, CA

New Zealand Spinach Planting Calendar

Activity When Date Range
Start Indoors January 16 Jan 16 – Jan 30
Transplant Outdoors March 6 Mar 6 – Mar 20
Direct Sow February 27 Feb 27 – Mar 20
Harvest May 1 May 1 – May 29

Plant 0.5" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

55–70 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 9b

📆 Growing Season

274 days in Humboldt County

Growing Tips for New Zealand Spinach in Humboldt County

Direct sow New Zealand Spinach outdoors after February 27 in Humboldt County when soil has warmed and frost danger has passed.

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

Humboldt County receives only 22" of rain annually. New Zealand Spinach needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Soak seeds overnight before planting. Direct sow after last frost. Pinch growing tips regularly to encourage bushy growth and tender new leaves.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant New Zealand Spinach in Humboldt County, CA?

Humboldt County is in Zone 9b with an average last frost of February 27. Plan your New Zealand Spinach planting based on this frost date — see the calendar above for exact timing.

What planting zone is Humboldt County, CA?

Humboldt County, California is in USDA Hardiness Zone 9b. The average last spring frost is February 27 and first fall frost is November 28.

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Your Humboldt County Garden Planner — Free

A 24-page printable planner built for Humboldt County (Zone 9b). 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 Humboldt 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.