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When to plant Grapes in Caribou County County,

Caribou County County's 109-day season only supports one Grapes planting per year. Sow between June 20 and July 4 for the best chance at full maturity before September 16.

When to Plant Grapes in Caribou County, ID

Grapes
Caribou County, Idaho Zone 5a June

June in Caribou County, Idaho — your action list

Your Caribou County, Idaho garden is entering a new phase. Here's what's on the schedule for June and why each task matters now.

Avg. last frost May 30
Avg. first frost September 16
Soil temp (4") 44°F
Watering Critical
Pest pressure High
Daylight 15.1 hrs
  1. Transplant grapes outside

    Pinch off the lowest leaves on each seedling before you plant — it reduces water loss while the roots catch up.

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Grapes are vigorous climbing vines producing clusters of sweet or wine-quality fruits. They require training on a trellis or arbor and annual pruning for best production.

Caribou County, Idaho is in USDA Zone 5a. The average last spring frost is May 30 and the first fall frost is September 16, giving you a growing season of approximately 109 days.

At an elevation of 6,562 feet, Caribou County receives approximately 15.3 inches of rainfall annually with predominantly loam soil. Summer highs average 81°F, so choose short-season varieties of Grapes to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Grapes successfully. Mulch heavily to conserve soil moisture.

Caribou County, ID (Zone 5a) Short season
109 days
Last Spring Frost May 30
109 growing days
First Fall Frost September 16

Caribou County Soil Profile

Soil Type

Loam

Soil pH

6.8-8.1

Drainage

Well Drained

Grapes Planting Risk Windows

Early Start (70% safe) ✓ Fits season
Transplant: Jun 8
Recommended (50%) ✓ Fits season
Transplant: Jun 20
Safe Start (90%) ✓ Fits season
Transplant: Jul 8

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 Caribou County

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

Soil pH

Your soil pH (6.8–8.1) is more alkaline than Grapes prefers (5.5–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.7%). Annual compost additions will help Grapes.

How to Plant Grapes

72"
Between Plants
96"
Between Rows

Grapes Water Budget

Plant needs
0.7″/week
Rainfall provides
0.6″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 129 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Grapes

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

Month Grapes Needs Rainfall You Supplement Action
Jan 1.2" 0" ❄️ Dormant
Feb 0.9" 0" ❄️ Dormant
Mar 1.4" 0" ❄️ Dormant
Apr 1.7" 0" ❄️ Dormant
May 3" 1.6" 1.4" 💧 Light watering
Jun 3" 1" 2" 🚿 Regular watering
Jul 3" 1.5" 1.5" 🚿 Regular watering
Aug 3" 1.4" 1.6" 🚿 Regular watering
Sep 3" 1.2" 1.8" 🚿 Regular watering
Oct 1.4" 0" ❄️ Dormant
Nov 1.1" 0" ❄️ Dormant
Dec 0.9" 0" ❄️ Dormant

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

Grapes 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.

Grapes needs ~9,809 GDD — county provides 1,171 GDD May not mature

Grapes Planting Timeline — Caribou County, ID

Grapes Planting Calendar

Activity When Date Range
Transplant Outdoors June 20 Jun 20 – Jul 4

· 72" apart · Rows 96" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.7"/week · Only during dry spells

📅 Days to Maturity

730–1095 days

🧪 Soil pH

Needs 5.5–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 5a

📆 Growing Season

109 days in Caribou County

Growing Tips for Grapes in Caribou County

Direct sow Grapes outdoors after May 30 in Caribou County when soil has warmed and frost danger has passed.

Your 109.0-day growing season in Caribou County is tight for Grapes (730.0-1095.0 days to maturity). Start indoors and choose early-maturing varieties.

General growing tips

Provide a strong trellis system. Prune heavily in late winter while dormant. Thin fruit clusters for larger berries. Good air circulation prevents fungal diseases.

Companion Planting

Good Companions

Avoid Planting Near

  • Cabbage
  • Radish

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Grapes in Caribou County, ID?

Caribou County is in Zone 5a with an average last frost of May 30. Plan your Grapes planting based on this frost date — see the calendar above for exact timing.

What planting zone is Caribou County, ID?

Caribou County, Idaho is in USDA Hardiness Zone 5a. The average last spring frost is May 30 and first fall frost is September 16.

When should I plant Grapes in Caribou County County, ?

In Caribou County County, , plant Grapes after the last frost (around May 30) and before the first frost (around September 16). Best results when soil holds above 50°F.

What growing zone is Caribou County County, for Grapes?

Caribou County County sits in USDA Zone 5a. Grapes grows reliably in zones 4a through 10b, so it's a good fit here.

Can Grapes grow in Caribou County County's climate?

Yes — Grapes grows well in Caribou County County's temperate climate. Caribou County County averages a 109-day frost-free season, with last frost around May 30 and first frost around September 16.

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Your Caribou County Garden Planner — Free

A 22-page printable planner built for Caribou County (Zone 5a). 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 Caribou County, ID. Local conditions may vary. Last updated: June 2026.

Sources & credits

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