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When to Plant Squash (Summer) in Lewis County, ID

Lewis County, Idaho Zone 6b May

Your May game plan for Lewis County, Idaho

If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.

Avg. last frost May 20
Avg. first frost September 23
Soil temp (4") 50°F
Watering High
Pest pressure Low
Daylight 14.8 hrs
  1. Sow squash (summer) where they'll grow

    Mark the row. Birds and stray feet both have opinions about unmarked beds.

A few tasks this May that'll pay off in June
  • Transplants going out: squash (summer)
  • Starting indoors: squash (summer)

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Summer squash includes zucchini, yellow crookneck, and pattypan varieties that are harvested young and tender. They are prolific producers in warm weather.

Lewis County, Idaho is in USDA Zone 6b. The average last spring frost is May 20 and the first fall frost is September 23, giving you a growing season of approximately 126 days.

At an elevation of 4,861 feet, Lewis County receives approximately 13.5 inches of rainfall annually with predominantly loam soil. Summer highs average 90°F, providing good warmth for Squash (Summer) during the growing season. With low rainfall, drip irrigation is essential for growing Squash (Summer) successfully. Mulch heavily to conserve soil moisture.

Lewis County, ID (Zone 6b) Short season
126 days
Last Spring Frost May 20
126 growing days
First Fall Frost September 23

Lewis County Soil Profile

Soil Type

Loam

Soil pH

6.7-8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (1 days to spare)
Start indoors: Apr 7 Transplant: May 26 🍅 Harvest: Jul 14 – Sep 15
Recommended (50%) ✓ Fits season (0 days to spare)
Start indoors: Apr 15 Transplant: Jun 3 🍅 Harvest: Jul 22 – Sep 23
Safe Start (90%) ✗ May not fit
Start indoors: May 6 Transplant: Jun 24 🍅 Harvest: Aug 12 – Oct 14

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 Lewis County

How your county's soil matches Squash (Summer)'s growing requirements.

Soil pH

Your soil pH (6.7–8.0) overlaps with Squash (Summer)'s range (6.0–7.5), though not a perfect match.

Soil Texture

The loam soil in Lewis County is excellent for Squash (Summer) — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.5%). Annual compost additions will help Squash (Summer).

How to Plant Squash (Summer)

1"
Planting Depth
30"
Between Plants
42"
Between Rows

Succession Planting Squash (Summer)

3
successive plantings in your 126-day season

Sow every 5.1 weeks. Last sowing by Jul 20 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.5″/week
You supply
0.7″/week
Watering frequency 1-2 times/week
Season total 740 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Squash (Summer)

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

Month Squash (Summer) Needs Rainfall You Supplement Action
Jan 1" 0" ❄️ Dormant
Feb 0.7" 0" ❄️ Dormant
Mar 1.1" 0" ❄️ Dormant
Apr 1.4" 0" ❄️ Dormant
May 4.3" 1.7" 2.6" 🚿 Regular watering
Jun 4.3" 0.8" 3.5" 🚿 Regular watering
Jul 4.3" 1.2" 3.1" 🚿 Regular watering
Aug 4.3" 1.4" 2.9" 🚿 Regular watering
Sep 4.3" 1.2" 3.1" 🚿 Regular watering
Oct 1.3" 0" ❄️ Dormant
Nov 0.8" 0" ❄️ Dormant
Dec 0.9" 0" ❄️ Dormant

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

Squash (Summer) 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.

Squash (Summer) needs ~962 GDD — county provides 2,205 GDD Excellent fit

Squash (Summer) Planting Timeline — Lewis County, ID

Squash (Summer) Planting Calendar

Activity When Date Range
Start Indoors April 15 Apr 15 – Apr 29
Transplant Outdoors June 3 Jun 3 – Jun 17
Direct Sow May 27 May 27 – Jun 17
Harvest July 22 Jul 22 – Sep 23

Plant 1" deep · 30" apart · Rows 42" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

45–65 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 6b

📆 Growing Season

126 days in Lewis County

Growing Tips for Squash (Summer) in Lewis County

Direct sow Squash (Summer) outdoors after May 20 in Lewis County when soil has warmed and frost danger has passed.

Common pests for Squash (Summer) in this region include squash vine borer and cucumber beetles. Use row covers early in the season and inspect plants weekly.

Lewis County receives only 14" of rain annually. Squash (Summer) needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Direct sow after last frost on mounds. Harvest frequently when fruits are 6-8 inches for best texture. Check plants daily as they grow rapidly in summer heat.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Squash (Summer) in Lewis County, ID?

Lewis County is in Zone 6b with an average last frost of May 20. Plan your Squash (Summer) planting based on this frost date — see the calendar above for exact timing.

What planting zone is Lewis County, ID?

Lewis County, Idaho is in USDA Hardiness Zone 6b. The average last spring frost is May 20 and first fall frost is September 23.

🌱

Your Lewis County Garden Planner — Free

A 24-page printable planner built for Lewis County (Zone 6b). 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 Lewis County, ID. 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.