Blog

When to Plant Lettuce in Mitchell, OR

Lettuce
Wheeler County, Oregon Zone 7a August

What to do in August

We've pulled the most time-sensitive tasks for Wheeler County, Oregon this August and put them front and centre. Tackle them in order.

Avg. last frost May 23
Avg. first frost September 23
Soil temp (4") 73°F
Watering Critical
Pest pressure High
Daylight 13.9 hrs
  1. Pick lettuce

    Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.

September prep starts now
  • First harvests: lettuce

Instant PDF download. No spam, unsubscribe any time.

Lettuce is a fast-growing cool-season green available in leaf, romaine, butterhead, and crisphead types. It is the foundation of salads and one of the easiest crops to grow.

Mitchell, Oregon is in USDA Zone 7a. The average last spring frost is May 23 and the first fall frost is September 23, giving you a growing season of approximately 123 days.

At an elevation of 2,175 feet, Wheeler County receives approximately 22.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Lettuce to ensure they mature before fall.

Mitchell, OR (Zone 7a) Short season
123 days
Last Spring Frost May 23
123 growing days
First Fall Frost September 23

Mitchell Soil Profile

Soil Type

Silt Loam

Soil pH

5.2-6.3

Drainage

Well Drained

Lettuce Planting Risk Windows

Early Start (70% safe) ✓ Fits season (12 days to spare)
Start indoors: Apr 11 Transplant: May 16 🍅 Harvest: Jun 20 – Aug 29
Recommended (50%) ✓ Fits season (18 days to spare)
Start indoors: Apr 18 Transplant: May 23 🍅 Harvest: Jun 27 – Sep 5
Safe Start (90%) ✓ Fits season (20 days to spare)
Start indoors: May 15 Transplant: Jun 19 🍅 Harvest: Jul 24 – Oct 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 Mitchell

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

Soil pH

Your soil pH (5.2–6.3) is more acidic than Lettuce prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

The silt loam soil in Wheeler County is excellent for Lettuce — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (5.7%) — Lettuce will thrive.

How to Plant Lettuce

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

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Succession Planting Lettuce

4
successive plantings in your 123-day season

Sow every 3.4 weeks. Last sowing by Jul 25 to harvest before frost.

For a dedicated fall crop, sow by Jul 15.

Lettuce Water Budget

Plant needs
0.7″/week
Rainfall provides
0.8″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

Monthly Watering Guide for Lettuce

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

Month Lettuce Needs Rainfall You Supplement Action
Jan 3" 0" ❄️ Dormant
Feb 2.3" 0" ❄️ Dormant
Mar 2.6" 0" ❄️ Dormant
Apr 1.6" 0" ❄️ Dormant
May 3" 1.5" 1.5" 🚿 Regular watering
Jun 3" 1" 2" 🚿 Regular watering
Jul 3" 0.4" 2.6" 🚿 Regular watering
Aug 3" 0.4" 2.6" 🚿 Regular watering
Sep 3" 0.8" 2.2" 🚿 Regular watering
Oct 2.1" 0" ❄️ Dormant
Nov 3.3" 0" ❄️ Dormant
Dec 3.8" 0" ❄️ Dormant

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

Lettuce 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.

Lettuce needs ~551 GDD — county provides 1,506 GDD Excellent fit

Lettuce Planting Timeline — Mitchell, OR

Lettuce Planting Calendar

Activity When Date Range
Start Indoors April 18 Apr 18 – May 2
Transplant Outdoors May 23 May 23 – Jun 6
Direct Sow May 9 May 9 – May 30
Harvest June 27 Jun 27 – Sep 5
Fall Sowing July 15 Jul 15 – Jul 29

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.7"/week · Natural rainfall sufficient

📅 Days to Maturity

30–60 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 7a

📆 Growing Season

123 days in Wheeler County

Growing Tips for Lettuce in Mitchell

Direct sow Lettuce outdoors after May 23 in Wheeler County when soil has warmed and frost danger has passed.

Common pests for Lettuce in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.

General growing tips

Sow seeds directly every 2 weeks for continuous harvest. Provide afternoon shade in warm weather to delay bolting. Harvest in the morning for crispest leaves.

Recommended Lettuce Varieties for Mitchell

Fast-maturing leaf and butterhead types

Salad Bowl (40d) Black Seeded Simpson (45d) Buttercrunch (50d)

Companion Planting

Good Companions

Avoid Planting Near

  • Celery

Check more plant combinations with our Companion Planting Checker →

🌾 Save Your Own Lettuce Seeds
Life Cycle Annual
Pollination Self-Pollinating
How to Collect Let plants bolt and flower. Harvest seed heads when fluffy.
Storage Store airtight; viable 6 years at 35°F, under 45% humidity.

Very easy to save. Let a few plants bolt each season.

🌱

Your Wheeler County Garden Planner — Free

A 22-page printable planner built for Wheeler County (Zone 7a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Wheeler County, OR. Local conditions may vary. Last updated: August 2026.