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When to Plant New Zealand Spinach in King County, WA

King County, Washington Zone 9a May

May in King County, Washington — your action list

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

Avg. last frost April 7
Avg. first frost October 30
Soil temp (4") 69°F
Watering High
Pest pressure High
Daylight 14.9 hrs
  1. Begin indoor sowing: new zealand spinach

    A seed-starting mix and a sunny window (or a grow light) are all you need. Keep soil warm — around 70°F — for fast germination.

June will be here before you know it — start on
  • First harvests: new zealand spinach

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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.

King County, Washington is in USDA Zone 9a. The average last spring frost is April 7 and the first fall frost is October 30, giving you a growing season of approximately 206 days.

At an elevation of 258 feet, King County receives approximately 37.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 89°F, providing good warmth for New Zealand Spinach during the growing season.

King County, WA (Zone 9a) Long season
206 days
Last Spring Frost April 7
206 growing days
First Fall Frost October 30
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King County Soil Profile

Soil Type

Silt Loam

Soil pH

5.7-6.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (113 days to spare)
Start indoors: Feb 10 Transplant: Mar 31 🍅 Harvest: May 26 – Jun 23
Recommended (50%) ✓ Fits season (115 days to spare)
Start indoors: Feb 24 Transplant: Apr 14 🍅 Harvest: Jun 9 – Jul 7
Safe Start (90%) ✓ Fits season (94 days to spare)
Start indoors: Apr 8 Transplant: May 27 🍅 Harvest: Jul 22 – Aug 19

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 King County

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

Soil pH

Your soil pH (5.7–6.4) overlaps with New Zealand Spinach's range (6.0–7.5), though not a perfect match.

Soil Texture

The silt loam soil in King County is excellent for New Zealand Spinach — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (5.5%) — New Zealand Spinach will thrive.

How to Plant New Zealand Spinach

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

Succession Planting New Zealand Spinach

4
successive plantings in your 206-day season

Sow every 6.3 weeks. Last sowing by Aug 21 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 428 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 5.9" 0" ❄️ Dormant
Feb 4.5" 0" ❄️ Dormant
Mar 3.4" 0" ❄️ Dormant
Apr 4.3" 2.9" 1.4" 💧 Light watering
May 4.3" 2" 2.3" 🚿 Regular watering
Jun 4.3" 1.3" 3" 🚿 Regular watering
Jul 4.3" 0.6" 3.7" 🚿 Regular watering
Aug 4.3" 0.7" 3.6" 🚿 Regular watering
Sep 4.3" 1.6" 2.7" 🚿 Regular watering
Oct 4.3" 3.4" 0.9" 💧 Light watering
Nov 5.6" 0" ❄️ Dormant
Dec 5.7" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in King 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 ~1,047 GDD — county provides 3,450 GDD Excellent fit

New Zealand Spinach Planting Timeline — King County, WA

New Zealand Spinach Planting Calendar

Activity When Date Range
Start Indoors February 24 Feb 24 – Mar 10
Transplant Outdoors April 14 Apr 14 – Apr 28
Direct Sow April 7 Apr 7 – Apr 28
Harvest June 9 Jun 9 – Jul 7

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

Month-by-Month Timeline

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

55–70 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 9a

📆 Growing Season

206 days in King County

Growing Tips for New Zealand Spinach in King County

Direct sow New Zealand Spinach outdoors after April 07 in King County when soil has warmed and frost danger has passed.

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 King County, WA?

King County is in Zone 9a with an average last frost of April 7. Plan your New Zealand Spinach planting based on this frost date — see the calendar above for exact timing.

What planting zone is King County, WA?

King County, Washington is in USDA Hardiness Zone 9a. The average last spring frost is April 7 and first fall frost is October 30.

🌱

Your King County Garden Planner — Free

A 24-page printable planner built for King 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 King County, WA. 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.