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When to Plant Parsley in Bonneville County, ID

Parsley is a biennial herb available in flat-leaf (Italian) and curly varieties. It is a nutritional powerhouse rich in vitamins C and K and adds fresh flavor to countless dishes.

Bonneville County, Idaho is in USDA Zone 5a. The average last spring frost is May 26 and the first fall frost is September 19, giving you a growing season of approximately 116 days.

At an elevation of 7,993 feet, Bonneville County receives approximately 20.9 inches of rainfall annually with predominantly loam soil. Summer highs average 85ยฐF, providing good warmth for Parsley during the growing season.

Bonneville County, ID (Zone 5a) Short season
116 days
Last Spring Frost May 26
116 growing days
First Fall Frost September 19

Bonneville County Soil Profile

Soil Type

Loam

Soil pH

6.5-8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 8 Transplant: May 6 🍅 Harvest: Jul 8 – Sep 9
Recommended (50%) ✗ May not fit
Start indoors: Apr 21 Transplant: May 19 🍅 Harvest: Jul 21 – Sep 22
Safe Start (90%) ✗ May not fit
Start indoors: May 17 Transplant: Jun 14 🍅 Harvest: Aug 16 – Oct 18

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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 301 gal / 100 sq ft
Drought risk

Water stress score is 8/10 โ€” consider drought-tolerant varieties and mulching

Parsley needs ~962 GDD — county provides 1,595 GDD Excellent fit

Parsley Planting Timeline โ€” Bonneville County, ID

Parsley Planting Calendar

Activity When Date Range
Start Indoors April 21 Apr 21 โ€“ May 5
Transplant Outdoors May 19 May 19 โ€“ Jun 2
Direct Sow May 12 May 12 โ€“ Jun 2
Fall Sowing July 11 Jul 11 โ€“ Jul 25
Harvest July 21 Jul 21 โ€“ Sep 22

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Partial Shade (3-6 hours)

Water

Moderate โ€” regular watering

Days to Maturity

60โ€“80 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 5a

Growing Season

116 days

Growing Tips for Bonneville County

Start seeds indoors 6-8 weeks before last frost. Soak seeds overnight as germination is slow. Harvest outer stems first to keep plants productive. Parsley attracts swallowtail butterflies.

Companion Planting

Good Companions

Avoid Planting Near

  • Mint
  • Lettuce

Level Up Your Garden

Frequently Asked Questions

When should I plant Parsley in Bonneville County, ID?

Bonneville County is in Zone 5a with an average last frost of May 26. Plan your Parsley planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Bonneville County, ID?

Bonneville County, Idaho is in USDA Hardiness Zone 5a. The average last spring frost is May 26 and first fall frost is September 19.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Bonneville County gardeners in Zone 5a organize planting dates, track what's growing, and never miss a planting window.

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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 Bonneville County, ID. Local conditions may vary. Last updated: April 2026.