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When to Plant Caraway in Boundary County, ID

Boundary County, Idaho Zone 6a May

Your May gardening checklist

Each item below is timed to Boundary County, Idaho's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost May 10
Avg. first frost September 22
Soil temp (4") 44°F
Watering High
Pest pressure Low
Daylight 15 hrs
  1. Harden off and plant caraway

    Water the tray well an hour before you transplant. Roots slide out cleanly and settle in faster.

Coming up in June — start thinking about
  • Starting indoors: caraway

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Caraway is a biennial herb grown for its distinctive crescent-shaped seeds used in rye bread, sauerkraut, and European cuisine. The leaves and roots are also edible.

Boundary County, Idaho is in USDA Zone 6a. The average last spring frost is May 10 and the first fall frost is September 22, giving you a growing season of approximately 135 days.

At an elevation of 5,105 feet, Boundary County receives approximately 21.1 inches of rainfall annually with predominantly loam soil. Summer highs average 87°F, providing good warmth for Caraway during the growing season.

Boundary County, ID (Zone 6a) Short season
135 days
Last Spring Frost May 10
135 growing days
First Fall Frost September 22
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Boundary County Soil Profile

Soil Type

Loam

Soil pH

6.7-8.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season
Start indoors: Mar 27 Transplant: Apr 24
Recommended (50%) ✓ Fits season
Start indoors: Apr 5 Transplant: May 3
Safe Start (90%) ✓ Fits season
Start indoors: Apr 30 Transplant: May 28

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 Boundary County

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

Soil pH

Your soil pH (6.7–8.3) overlaps with Caraway's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.3%). Annual compost additions will help Caraway.

How to Plant Caraway

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

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

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.7″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 495 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Caraway

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

Month Caraway Needs Rainfall You Supplement Action
Jan 1.6" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 1.9" 0" ❄️ Dormant
Apr 2" 0" ❄️ Dormant
May 4.3" 2.7" 1.6" 💧 Light watering
Jun 4.3" 1.6" 2.7" 🚿 Regular watering
Jul 4.3" 1.8" 2.5" 🚿 Regular watering
Aug 4.3" 1.9" 2.4" 🚿 Regular watering
Sep 4.3" 1.6" 2.7" 🚿 Regular watering
Oct 2.1" 0" ❄️ Dormant
Nov 1.5" 0" ❄️ Dormant
Dec 1.3" 0" ❄️ Dormant

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

Caraway 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.

Caraway needs ~6,214 GDD — county provides 2,058 GDD May not mature

Caraway Planting Timeline — Boundary County, ID

Caraway Planting Calendar

Activity When Date Range
Start Indoors April 5 Apr 5 – Apr 19
Transplant Outdoors May 3 May 3 – May 17
Direct Sow April 26 Apr 26 – May 17
Fall Sowing July 14 Jul 14 – Jul 28

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors Direct Sow
May Transplant Outdoors Direct Sow
June
July Fall Sowing
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

365–450 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 6a

📆 Growing Season

135 days in Boundary County

Growing Tips for Caraway in Boundary County

Direct sow Caraway outdoors after May 10 in Boundary County when soil has warmed and frost danger has passed.

Your 135.0-day growing season in Boundary County is tight for Caraway (365.0-450.0 days to maturity). Start indoors and choose early-maturing varieties.

Common pests for Caraway in this region include carrot rust fly and parsleyworm. Use row covers early in the season and inspect plants weekly.

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

General growing tips

Direct sow in spring or fall. Caraway produces seeds in its second year. Harvest seed heads when they turn brown. The young leaves can be used like parsley.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Caraway in Boundary County, ID?

Boundary County is in Zone 6a with an average last frost of May 10. Plan your Caraway planting based on this frost date — see the calendar above for exact timing.

What planting zone is Boundary County, ID?

Boundary County, Idaho is in USDA Hardiness Zone 6a. The average last spring frost is May 10 and first fall frost is September 22.

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Your Boundary County Garden Planner — Free

A 24-page printable planner built for Boundary 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 Boundary 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.