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When to Plant Cranberries in Adams County, ID

Adams County, Idaho Zone 6a May

Your May planting checklist for Adams County, Idaho

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

Avg. last frost May 20
Avg. first frost September 25
Soil temp (4") 39°F
Watering High
Pest pressure Low
Daylight 14.6 hrs
Get ahead of June
  • Transplants going out: cranberries

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Cranberries are low-growing, vine-like shrubs that produce tart red berries in fall. They grow in acidic, boggy conditions and are surprisingly easy to cultivate.

Adams County, Idaho is in USDA Zone 6a. The average last spring frost is May 20 and the first fall frost is September 25, giving you a growing season of approximately 128 days.

At an elevation of 6,593 feet, Adams County receives approximately 20.6 inches of rainfall annually with predominantly loam soil. Summer highs average 85°F, providing good warmth for Cranberries during the growing season.

Adams County, ID (Zone 6a) Short season
128 days
Last Spring Frost May 20
128 growing days
First Fall Frost September 25

Adams County Soil Profile

Soil Type

Loam

Soil pH

6.3-8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season
Transplant: May 26
Recommended (50%) ✓ Fits season
Transplant: Jun 10
Safe Start (90%) ✓ Fits season
Transplant: Jul 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 Adams County

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

Soil pH

Your soil pH (6.3–8.0) is more alkaline than Cranberries prefers (4.0–5.5). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Adams County is excellent for Cranberries — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Cranberries is a heavy drinker but your soil drains very quickly. Mulch heavily and consider drip irrigation.

Organic Matter

Organic matter is moderate (2.2%). Annual compost additions will help Cranberries.

How to Plant Cranberries

36"
Between Plants
48"
Between Rows

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
0.7″/week
You supply
1.5″/week
Watering frequency 2-3 times/week
Season total 1,742 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Cranberries

Cranberries needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.

Month Cranberries Needs Rainfall You Supplement Action
Jan 1.4" 0" ❄️ Dormant
Feb 1.1" 0" ❄️ Dormant
Mar 1.9" 0" ❄️ Dormant
Apr 2" 0" ❄️ Dormant
May 6.5" 2.6" 3.9" 🚿 Regular watering
Jun 6.5" 1.4" 5.1" 🚿 Regular watering
Jul 6.5" 2" 4.5" 🚿 Regular watering
Aug 6.5" 2.1" 4.4" 🚿 Regular watering
Sep 6.5" 1.7" 4.8" 🚿 Regular watering
Oct 1.8" 0" ❄️ Dormant
Nov 1.4" 0" ❄️ Dormant
Dec 1.2" 0" ❄️ Dormant

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

Cranberries 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.

Cranberries needs ~12,547 GDD — county provides 1,760 GDD May not mature

Cranberries Planting Timeline — Adams County, ID

Cranberries Planting Calendar

Activity When Date Range
Transplant Outdoors June 10 Jun 10 – Jun 24

· 36" apart · Rows 48" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April
May
June Transplant Outdoors
July
August
September
October
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.5"/week · 2-3 times/week

📅 Days to Maturity

730–1095 days

🧪 Soil pH

Needs 4–5.5 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 6a

📆 Growing Season

128 days in Adams County

Growing Tips for Cranberries in Adams County

Direct sow Cranberries outdoors after May 20 in Adams County when soil has warmed and frost danger has passed.

Your 128.0-day growing season in Adams County is tight for Cranberries (730.0-1095.0 days to maturity). Start indoors and choose early-maturing varieties.

Adams County receives only 21" of rain annually. Cranberries needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Create an acidic, consistently moist bed with peat moss. Cranberries do not need to be flooded to grow; flooding is only used for commercial harvesting. Mulch with sand in early spring.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Cranberries in Adams County, ID?

Adams County is in Zone 6a with an average last frost of May 20. Plan your Cranberries planting based on this frost date — see the calendar above for exact timing.

What planting zone is Adams County, ID?

Adams County, Idaho is in USDA Hardiness Zone 6a. The average last spring frost is May 20 and first fall frost is September 25.

🌱

Your Adams County Garden Planner — Free

A 24-page printable planner built for Adams County (Zone 6a). 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 Adams 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.