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When to Plant Shallot in Bonneville County, ID

Bonneville County, Idaho Zone 5b May

May in the garden — Bonneville County, Idaho

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Bonneville County, Idaho.

Avg. last frost May 26
Avg. first frost September 19
Soil temp (4") 32°F
Watering High
Pest pressure Low
Daylight 14.5 hrs
  1. Get shallot in the ground

    Plant tomatoes deep — bury the stem up to the first true leaves to grow extra roots. Everything else goes in at the same depth it grew in the tray.

  2. Direct-sow shallot

    Mark the row. Birds and stray feet both have opinions about unmarked beds.

June prep starts now
  • Starting indoors: shallot

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Shallots are a gourmet allium prized for their complex, sweet, and mild flavor. Each bulb multiplies into a cluster, making them easy and rewarding to grow.

Bonneville County, Idaho is in USDA Zone 5b. 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 85°F, providing good warmth for Shallot during the growing season.

Bonneville County, ID (Zone 5b) Short season
116 days
Last Spring Frost May 26
116 growing days
First Fall Frost September 19
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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 13 🍅 Harvest: Aug 12 – Sep 30
Recommended (50%) ✗ May not fit
Start indoors: Apr 21 Transplant: May 26 🍅 Harvest: Aug 25 – Oct 13
Safe Start (90%) ✗ May not fit
Start indoors: May 17 Transplant: Jun 21 🍅 Harvest: Sep 20 – Nov 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 Bonneville County

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

Soil pH

Your soil pH (6.5–8.0) is more alkaline than Shallot prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.4%). Annual compost additions will help Shallot.

How to Plant Shallot

1"
Planting Depth
6"
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
0.8″/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 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Shallot

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

Month Shallot Needs Rainfall You Supplement Action
Jan 1.5" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 2" 0" ❄️ Dormant
Apr 2.4" 0" ❄️ Dormant
May 4.3" 2.2" 2.1" 💧 Light watering
Jun 4.3" 1.7" 2.6" 🚿 Regular watering
Jul 4.3" 2.1" 2.2" 🚿 Regular watering
Aug 4.3" 1.9" 2.4" 🚿 Regular watering
Sep 4.3" 1.7" 2.6" 🚿 Regular watering
Oct 1.9" 0" ❄️ Dormant
Nov 1.4" 0" ❄️ Dormant
Dec 1.1" 0" ❄️ Dormant

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

Shallot 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.

Shallot needs ~1,444 GDD — county provides 1,595 GDD Good fit

Shallot Planting Timeline — Bonneville County, ID

Shallot Planting Calendar

Activity When Date Range
Start Indoors April 21 Apr 21 – May 5
Transplant Outdoors May 26 May 26 – Jun 9
Direct Sow May 12 May 12 – Jun 2
Harvest August 25 Aug 25 – Oct 13
Fall Sowing July 11 Jul 11 – Jul 25

Plant 1" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

90–120 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 5b

📆 Growing Season

116 days in Bonneville County

Growing Tips for Shallot in Bonneville County

Direct sow Shallot outdoors after May 26 in Bonneville County when soil has warmed and frost danger has passed.

Your 116.0-day growing season in Bonneville County is tight for Shallot (90.0-120.0 days to maturity). Start indoors and choose early-maturing varieties.

Common pests for Shallot in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.

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

General growing tips

Plant sets in fall for spring harvest or early spring for summer harvest. Mulch heavily if overwintering. Harvest when tops brown and dry, then cure for storage.

Companion Planting

Good Companions

Avoid Planting Near

  • Peas
  • Green Beans

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Shallot in Bonneville County, ID?

Bonneville County is in Zone 5b with an average last frost of May 26. Plan your Shallot planting based on this frost date — see the calendar above for exact timing.

What planting zone is Bonneville County, ID?

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

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Your Bonneville County Garden Planner — Free

A 24-page printable planner built for Bonneville County (Zone 5b). 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 Bonneville 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.