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When to Plant Medlar in Caribou County, ID

Caribou County, Idaho Zone 5a May

May in Caribou County, Idaho — your action list

May is a pivotal month for Caribou County, Idaho gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost May 30
Avg. first frost September 16
Soil temp (4") 34°F
Watering High
Pest pressure Low
Daylight 14.4 hrs
Before June arrives, get these ready
  • Transplants going out: medlar

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Medlar is a small ornamental tree producing unusual open-ended fruits that must be bletted (softened by frost) before eating. The flavor is complex, like spiced apple butter.

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 Medlar to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Medlar 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
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Caribou County Soil Profile

Soil Type

Loam

Soil pH

6.8-8.1

Drainage

Well Drained

Plant 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 Medlar's growing requirements.

Soil pH

Your soil pH (6.8–8.1) overlaps with Medlar's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

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

How to Plant Medlar

120"
Between Plants
144"
Between Rows

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.6″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 478 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Medlar

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

Month Medlar 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 4.3" 1.6" 2.7" 🚿 Regular watering
Jun 4.3" 1" 3.3" 🚿 Regular watering
Jul 4.3" 1.5" 2.8" 🚿 Regular watering
Aug 4.3" 1.4" 2.9" 🚿 Regular watering
Sep 4.3" 1.2" 3.1" 🚿 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.

Medlar 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.

Medlar needs ~15,695 GDD — county provides 1,171 GDD May not mature

Medlar Planting Timeline — Caribou County, ID

Medlar Planting Calendar

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

· 120" apart · Rows 144" apart

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

1095–1825 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 5a

📆 Growing Season

109 days in Caribou County

Growing Tips for Medlar in Caribou County

Direct sow Medlar 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 Medlar (1095.0-1825.0 days to maturity). Start indoors and choose early-maturing varieties.

Caribou County receives only 15" of rain annually. Medlar needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Plant in well-drained soil. Medlars are self-fertile and need minimal pruning. Harvest after the first frost and allow to soften (blet) indoors for 2-3 weeks before eating.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Medlar in Caribou County, ID?

Caribou County is in Zone 5a with an average last frost of May 30. Plan your Medlar 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.

🌱

Your Caribou County Garden Planner — Free

A 24-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: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.