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When to Plant Snap Peas in San Juan County, WA

San Juan County, Washington Zone 9a May

Your May planting checklist for San Juan County, Washington

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

Avg. last frost March 26
Avg. first frost November 3
Soil temp (4") 71°F
Watering High
Pest pressure High
Daylight 15 hrs
  1. Get snap peas seeds going inside

    Starting these indoors now means sturdy transplants ready the moment your soil warms up.

  2. Collect snap peas at their peak

    This is the payoff month. Bring a basket, bring a friend, and get into the beds.

To set up a strong June, finish these tasks
  • First harvests: snap peas

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Snap peas have edible pods with plump, sweet peas inside, combining the best features of snow peas and garden peas. They are a garden favorite for fresh eating.

San Juan County, Washington is in USDA Zone 9a. The average last spring frost is March 26 and the first fall frost is November 3, giving you a growing season of approximately 222 days.

At an elevation of 371 feet, San Juan County receives approximately 40.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 82°F, so choose short-season varieties of Snap Peas to ensure they mature before fall.

San Juan County, WA (Zone 9a) Long season
222 days
Last Spring Frost March 26
222 growing days
First Fall Frost November 3
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San Juan County Soil Profile

Soil Type

Silt Loam

Soil pH

5.4-6.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (105 days to spare)
Start indoors: Feb 5 Transplant: Mar 26 🍅 Harvest: May 21 – Jul 16
Recommended (50%) ✓ Fits season (103 days to spare)
Start indoors: Feb 12 Transplant: Apr 2 🍅 Harvest: May 28 – Jul 23
Safe Start (90%) ✓ Fits season (101 days to spare)
Start indoors: Mar 14 Transplant: May 2 🍅 Harvest: Jun 27 – Aug 22

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 San Juan County

How your county's soil matches Snap Peas's growing requirements.

Soil pH

Your soil pH (5.4–6.4) is more acidic than Snap Peas prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

The silt loam soil in San Juan County is excellent for Snap Peas — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Drainage is adequate for Snap Peas.

Organic Matter

Organic matter is excellent (4.8%) — Snap Peas will thrive.

How to Plant Snap Peas

1"
Planting Depth
4"
Between Plants
18"
Between Rows

Succession Planting Snap Peas

4
successive plantings in your 222-day season

Sow every 6.3 weeks. Last sowing by Aug 25 to harvest before frost.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
0.8″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 269 gal / 100 sq ft

Monthly Watering Guide for Snap Peas

Snap Peas needs approximately 0.7 inches of water per week (3" per month). Here's how your county's rainfall compares month by month.

Month Snap Peas Needs Rainfall You Supplement Action
Jan 5.7" 0" ❄️ Dormant
Feb 4.7" 0" ❄️ Dormant
Mar 3" 4.1" 0" ✅ Rainfall sufficient
Apr 3" 2.6" 0.4" 💧 Light watering
May 3" 2.6" 0.4" 💧 Light watering
Jun 3" 1.5" 1.5" 🚿 Regular watering
Jul 3" 0.6" 2.4" 🚿 Regular watering
Aug 3" 0.8" 2.2" 🚿 Regular watering
Sep 3" 1.8" 1.2" 💧 Light watering
Oct 3" 3.4" 0" ✅ Rainfall sufficient
Nov 3" 6.4" 0" ✅ Rainfall sufficient
Dec 6.6" 0" ❄️ Dormant

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

Snap Peas 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.

Snap Peas needs ~719 GDD — county provides 2,553 GDD Excellent fit

Snap Peas Planting Timeline — San Juan County, WA

Snap Peas Planting Calendar

Activity When Date Range
Start Indoors February 12 Feb 12 – Feb 26
Transplant Outdoors April 2 Apr 2 – Apr 16
Direct Sow March 26 Mar 26 – Apr 16
Harvest May 28 May 28 – Jul 23

Plant 1" deep · 4" apart · Rows 18" apart

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.7"/week · Only during dry spells

📅 Days to Maturity

55–70 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 9a

📆 Growing Season

222 days in San Juan County

Growing Tips for Snap Peas in San Juan County

Direct sow Snap Peas outdoors after March 26 in San Juan County when soil has warmed and frost danger has passed.

Common pests for Snap Peas in this region include bean beetles and aphids. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow in early spring as soon as soil can be worked. Provide a trellis 4-6 feet tall. Harvest when pods are plump and snap cleanly when bent.

Companion Planting

Good Companions

Avoid Planting Near

  • Onion
  • Garlic

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Snap Peas in San Juan County, WA?

San Juan County is in Zone 9a with an average last frost of March 26. Plan your Snap Peas planting based on this frost date — see the calendar above for exact timing.

What planting zone is San Juan County, WA?

San Juan County, Washington is in USDA Hardiness Zone 9a. The average last spring frost is March 26 and first fall frost is November 3.

🌱

Your San Juan County Garden Planner — Free

A 24-page printable planner built for San Juan 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 San Juan 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.