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When to plant Lilies in Howard County County,

Howard County County's short 154-day growing season means one Lilies planting between May 18 and June 1. No fall crop in Zone 4b.

When to Plant Lilies in Howard County, IA

Howard County, Iowa Zone 4b June

Howard County, Iowa gardeners: here's your June plan

Welcome to June in Zone 4b. These are the moves that will have the biggest impact on your growing season.

Avg. last frost May 4
Avg. first frost October 5
Soil temp (4") 62°F
Watering Low
Pest pressure High
Daylight 15.2 hrs

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Lilies (Lilium spp.) are among the most impressive summer-blooming bulbs, delivering bold, upward- or outward-facing trumpet blooms on tall stems from June through August. Asiatic hybrids are the most cold-hardy, earliest to bloom, and easiest to grow; Oriental hybrids bloom later with intensely fragrant, larger flowers. Orienpet (OT) hybrids combine the hardiness of Asiatics with the fragrance and size of Orientals. True lilies (not to be confused with daylilies, which are Hemerocallis) form scaly bulbs that persist and multiply underground, returning reliably each year with increasingly large clumps.

Howard County, Iowa is in USDA Zone 4b. The average last spring frost is May 4 and the first fall frost is October 5, giving you a growing season of approximately 154 days.

At an elevation of 1,297 feet, Howard County receives approximately 39.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Lilies to ensure they mature before fall.

Perennial Blooms in Summer Pollinator-friendly Good for cutting Fragrant
Howard County, IA (Zone 4b) Moderate season
154 days
Last Spring Frost May 4
154 growing days
First Fall Frost October 5

Howard County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-7.3

Drainage

Well Drained

Lilies Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 12 🌸 Bloom: Aug 4 – Oct 6
Recommended (50%) ✗ May not fit
Transplant: May 18 🌸 Bloom: Aug 10 – Oct 12
Safe Start (90%) ✗ May not fit
Transplant: May 30 🌸 Bloom: Aug 22 – Oct 24

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 Howard County

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

Soil pH

Your soil pH (6.1–7.3) is more alkaline than Lilies prefers (6.0–6.5). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

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

How to Plant Lilies

5"
Planting Depth
12"
Between Plants
18"
Between Rows

Succession Planting Lilies

2
successive plantings in your 154-day season

Sow every 8 weeks. Last sowing by Jun 07 to harvest before frost.

Lilies Water Budget

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

Monthly Watering Guide for Lilies

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

Month Lilies Needs Rainfall You Supplement Action
Jan 1.8" 0" ❄️ Dormant
Feb 1.7" 0" ❄️ Dormant
Mar 2.8" 0" ❄️ Dormant
Apr 3.9" 0" ❄️ Dormant
May 4.3" 4.8" 0" ✅ Rainfall sufficient
Jun 4.3" 4.4" 0" ✅ Rainfall sufficient
Jul 4.3" 4.3" 0" ✅ Rainfall sufficient
Aug 4.3" 4" 0.3" 💧 Light watering
Sep 4.3" 3.5" 0.8" 💧 Light watering
Oct 4.3" 3.3" 1" 💧 Light watering
Nov 2.5" 0" ❄️ Dormant
Dec 2.6" 0" ❄️ Dormant

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

Lilies 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.

Lilies needs ~1,164 GDD — county provides 1,886 GDD Excellent fit

Lilies Planting Timeline — Howard County, IA

Lilies Planting Calendar

Activity When Date Range
Transplant Outdoors May 18 May 18 – Jun 1
Bloom August 10 Aug 10 – Oct 12

Plant 5" deep · 12" apart · Rows 18" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

70–120 days

🧪 Soil pH

Needs 6–6.5 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 4b

📆 Growing Season

154 days in Howard County

Growing Tips for Lilies in Howard County

Direct sow Lilies outdoors after May 04 in Howard County when soil has warmed and frost danger has passed.

General growing tips

Plant bulbs in fall (preferred, September–October) or spring, setting them 3 times their diameter deep (typically 4–6 inches) with the pointed end up. Lilies need excellent drainage — they will rot in wet or heavy clay soils. Site with full sun on stems and blooms but cool, shaded soil at the base (ground cover or shallow-rooted annuals at their feet is ideal). Remove spent blooms but leave stems and foliage until they yellow naturally, as the bulb needs the foliage to photosynthesize and rebuild energy stores. Red lily beetle is a serious pest in the Northeast and Pacific Northwest; inspect plants regularly and hand-pick adults and larvae. Never plant Oriental or Asiatic lilies near cats — all Lilium species are highly toxic to cats. Year 2+ bulbs produce the most stems and largest blooms.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Lilies in Howard County, IA?

Howard County is in Zone 4b with an average last frost of May 4. Plan your Lilies planting based on this frost date — see the calendar above for exact timing.

What planting zone is Howard County, IA?

Howard County, Iowa is in USDA Hardiness Zone 4b. The average last spring frost is May 4 and first fall frost is October 5.

When should I plant Lilies in Howard County County, ?

In Howard County County, , plant Lilies after the last frost (around May 4) and before the first frost (around October 5). Best results when soil holds above 50°F.

What growing zone is Howard County County, for Lilies?

Howard County County sits in USDA Zone 4b. Lilies grows reliably in zones 3a through 9a, so it's a good fit here.

Can Lilies grow in Howard County County's climate?

Yes — Lilies grows well in Howard County County's temperate climate. Howard County County averages a 154-day frost-free season, with last frost around May 4 and first frost around October 5.

🌱

Your Howard County Garden Planner — Free

A 22-page printable planner built for Howard County (Zone 4b). 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 Howard County, IA. Local conditions may vary. Last updated: June 2026.

Sources & credits

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