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When to plant Nasturtium in Webster County County,

In Zone 5a (Webster County County), direct-sow Nasturtium between May 5 and May 26 for spring, after the April 28 last-frost mark.

When to Plant Nasturtium in Webster County, IA

Webster County, Iowa Zone 5a June

June in Webster County, Iowa — your action list

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

Avg. last frost April 28
Avg. first frost October 6
Soil temp (4") 64°F
Watering Moderate
Pest pressure High
Daylight 15.1 hrs
  1. Bring in the nasturtium

    Morning harvests are best — cooler temperatures mean crisper produce and longer fridge life.

Before July arrives, get these ready
  • First harvests: nasturtium

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Nasturtium (Tropaeolum majus) is a fast-growing annual with distinctive round, lily-pad leaves and bold trumpet-shaped blooms in warm oranges, reds, and yellows. Both the flowers and leaves are edible with a peppery watercress flavor. Planted near vegetables, nasturtiums act as a sacrifice trap-crop, luring aphids away from more valuable plants. They thrive in poor, dry soil — rich conditions produce lush foliage but few flowers.

Webster County, Iowa is in USDA Zone 5a. The average last spring frost is April 28 and the first fall frost is October 6, giving you a growing season of approximately 161 days.

At an elevation of 1,065 feet, Webster County receives approximately 30.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Nasturtium to ensure they mature before fall.

Annual Blooms in Multi-season Pollinator-friendly Deer-resistant Good for cutting Fragrant
Webster County, IA (Zone 5a) Moderate season
161 days
Last Spring Frost April 28
161 growing days
First Fall Frost October 6

Webster County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-7.3

Drainage

Well Drained

Nasturtium Planting Risk Windows

Early Start (70% safe) ✓ Fits season (0 days to spare)
Start indoors: Mar 25 Transplant: Apr 29 🌸 Bloom: Jun 24 – Sep 30
Recommended (50%) ✓ Fits season (0 days to spare)
Start indoors: Mar 31 Transplant: May 5 🌸 Bloom: Jun 30 – Oct 6
Safe Start (90%) ✗ May not fit
Start indoors: Apr 16 Transplant: May 21 🌸 Bloom: Jul 16 – Oct 22

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 Webster County

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

Soil pH

Your soil pH (6.2–7.3) is within Nasturtium's preferred range (6.0–8.0).

Soil Texture

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

Drainage

Drainage is adequate for Nasturtium.

Organic Matter

Organic matter is excellent (4.4%) — Nasturtium will thrive.

How to Plant Nasturtium

0.5"
Planting Depth
10"
Between Plants
12"
Between Rows

Succession Planting Nasturtium

3
successive plantings in your 161-day season

Sow every 6.3 weeks. Last sowing by Aug 02 to harvest before frost.

Nasturtium Water Budget

Plant needs
0.5″/week
Rainfall provides
0.8″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

Monthly Watering Guide for Nasturtium

Nasturtium needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.

Month Nasturtium Needs Rainfall You Supplement Action
Jan 1.4" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 2.3" 0" ❄️ Dormant
Apr 2.2" 2.6" 0" ✅ Rainfall sufficient
May 2.2" 3.4" 0" ✅ Rainfall sufficient
Jun 2.2" 3.6" 0" ✅ Rainfall sufficient
Jul 2.2" 3.1" 0" ✅ Rainfall sufficient
Aug 2.2" 3" 0" ✅ Rainfall sufficient
Sep 2.2" 3.2" 0" ✅ Rainfall sufficient
Oct 2.2" 2.5" 0" ✅ Rainfall sufficient
Nov 2.2" 0" ❄️ Dormant
Dec 1.7" 0" ❄️ Dormant

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

Nasturtium 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.

Nasturtium needs ~600 GDD — county provides 1,610 GDD Excellent fit

Nasturtium Planting Timeline — Webster County, IA

Nasturtium Planting Calendar

Activity When Date Range
Start Indoors March 31 Mar 31 – Apr 14
Transplant Outdoors May 5 May 5 – May 19
Direct Sow May 5 May 5 – May 26
Bloom June 30 Jun 30 – Oct 6

Plant 0.5" deep · 10" apart · Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

55–65 days

🧪 Soil pH

Needs 6–8 · Your soil: ideal

🗺️ USDA Zone

Zone 5a

📆 Growing Season

161 days in Webster County

Growing Tips for Nasturtium in Webster County

Direct sow Nasturtium outdoors after April 28 in Webster County when soil has warmed and frost danger has passed.

General growing tips

Direct-sow large seeds 1/2 inch deep after last frost; soak seeds overnight to speed germination (7-10 days). Nasturtiums dislike root disturbance so direct sowing is strongly preferred. Avoid fertilizing — poor soil brings the best bloom. Trailing types can cover banks and climb trellises; dwarf types suit containers. In hot climates (zones 9+) plant in fall for winter/spring bloom as plants struggle in peak summer heat.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Nasturtium in Webster County, IA?

Webster County is in Zone 5a with an average last frost of April 28. Plan your Nasturtium planting based on this frost date — see the calendar above for exact timing.

What planting zone is Webster County, IA?

Webster County, Iowa is in USDA Hardiness Zone 5a. The average last spring frost is April 28 and first fall frost is October 6.

When should I plant Nasturtium in Webster County County, ?

In Webster County County, , plant Nasturtium after the last frost (around April 28) and before the first frost (around October 6). Best results when soil holds above 50°F.

What growing zone is Webster County County, for Nasturtium?

Webster County County sits in USDA Zone 5a. Nasturtium grows reliably in zones 2a through 11b, so it's a good fit here.

Can Nasturtium grow in Webster County County's climate?

Yes — Nasturtium grows well in Webster County County's temperate climate. Webster County County averages a 161-day frost-free season, with last frost around April 28 and first frost around October 6.

🌱

Your Webster County Garden Planner — Free

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

Sources & credits

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