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When to plant Shallot in Black Hawk County, IA

In Black Hawk County, plant Shallot in spring between April 15 and May 6, once soil temps hold above 50°F. Black Hawk County's last frost averages April 29, so time plantings around the expected last-frost window for best survival. For a fall crop, sow between July 29 and August 12 — roughly 120 days before the first frost on October 7.

When to Plant Shallot in Black Hawk County, IA

Black Hawk County, Iowa Zone 5a June

Black Hawk County, Iowa gardeners: here's your June plan

June rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Black Hawk County, Iowa.

Avg. last frost April 29
Avg. first frost October 7
Soil temp (4") 65°F
Watering Low
Pest pressure High
Daylight 15.1 hrs
  1. Start shallot indoors

    Starting these indoors now means sturdy transplants ready the moment your soil warms up.

Get ahead of July
  • First harvests: shallot
  • Fall sowing: 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.

Black Hawk County, Iowa is in USDA Zone 5a. The average last spring frost is April 29 and the first fall frost is October 7, giving you a growing season of approximately 161 days.

At an elevation of 1,380 feet, Black Hawk County receives approximately 38.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Shallot to ensure they mature before fall.

Black Hawk County, IA (Zone 5a) Moderate season
161 days
Last Spring Frost April 29
161 growing days
First Fall Frost October 7

Black Hawk County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-7.1

Drainage

Well Drained

Shallot Planting Risk Windows

Early Start (70% safe) ✓ Fits season (22 days to spare)
Start indoors: Mar 19 Transplant: Apr 23 🍅 Harvest: Jul 23 – Sep 10
Recommended (50%) ✓ Fits season (21 days to spare)
Start indoors: Mar 25 Transplant: Apr 29 🍅 Harvest: Jul 29 – Sep 16
Safe Start (90%) ✓ Fits season (16 days to spare)
Start indoors: Apr 8 Transplant: May 13 🍅 Harvest: Aug 12 – Sep 30

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 Black Hawk County

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

Soil pH

Your soil pH (6.2–7.1) overlaps with Shallot's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.5%) — Shallot will thrive.

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.

Shallot Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
Watering frequency Only during dry spells
Season total 1 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — 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 1.7" 0" ❄️ Dormant
Feb 1.6" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 4.3" 3.5" 0.8" 💧 Light watering
May 4.3" 5" 0" ✅ Rainfall sufficient
Jun 4.3" 5.3" 0" ✅ Rainfall sufficient
Jul 4.3" 3.6" 0.7" 💧 Light watering
Aug 4.3" 4.1" 0.2" 💧 Light watering
Sep 4.3" 3.5" 0.8" 💧 Light watering
Oct 4.3" 3.2" 1.1" 💧 Light watering
Nov 2.4" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Black Hawk 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 ~1,365 GDD — county provides 2,093 GDD Excellent fit

Shallot Planting Timeline — Black Hawk County, IA

Shallot Planting Calendar

Activity When Date Range
Start Indoors March 25 Mar 25 – Apr 8
Transplant Outdoors April 29 Apr 29 – May 13
Direct Sow April 15 Apr 15 – May 6
Harvest July 29 Jul 29 – Sep 16
Fall Sowing July 29 Jul 29 – Aug 12

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

Month-by-Month Timeline

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

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: acceptable

🗺️ USDA Zone

Zone 5a

📆 Growing Season

161 days in Black Hawk County

Growing Tips for Shallot in Black Hawk County

Direct sow Shallot outdoors after April 29 in Black Hawk County when soil has warmed and frost danger has passed.

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

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 Black Hawk County, IA?

Black Hawk County is in Zone 5a with an average last frost of April 29. Plan your Shallot planting based on this frost date — see the calendar above for exact timing.

What planting zone is Black Hawk County, IA?

Black Hawk County, Iowa is in USDA Hardiness Zone 5a. The average last spring frost is April 29 and first fall frost is October 7.

When should I plant Shallot in Black Hawk County, IA?

In Black Hawk County, IA, plant Shallot after the last frost (around April 29) and before the first frost (around October 7). Best results when soil holds above 50°F.

What growing zone is Black Hawk County, IA for Shallot?

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

Can Shallot grow in Black Hawk County's climate?

Yes — Shallot grows well in Black Hawk County's temperate climate. Black Hawk County averages a 161-day frost-free season, with last frost around April 29 and first frost around October 7.

🌱

Your Black Hawk County Garden Planner — Free

A 22-page printable planner built for Black Hawk 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 Black Hawk County, IA. Local conditions may vary. Last updated: June 2026.

Sources & credits

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