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When to Plant Coreopsis in Sioux County, NE

Sioux County, Nebraska Zone 5a July

Your July game plan for Sioux County, Nebraska

A quick July briefing for Sioux County, Nebraska gardeners — what's urgent, what's next, and what can wait.

Avg. last frost May 16
Avg. first frost September 22
Soil temp (4") 71°F
Watering High
Pest pressure High
Daylight 14.8 hrs
  1. Sow coreopsis in trays indoors

    A seed-starting mix and a sunny window (or a grow light) are all you need. Keep soil warm — around 70°F — for fast germination.

August will be here before you know it — start on
  • First harvests: coreopsis

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Coreopsis (Tickseed) is a cheerful, long-blooming native perennial that produces a continuous flush of bright yellow, gold, or bi-colored daisy-like flowers from early summer well into fall. One of the most reliable cut-and-come-again bloomers in the perennial garden, it thrives in hot, dry, sunny conditions and poor soil where many competitors struggle. An invaluable nectar source for native bees and butterflies, and a butterfly host plant for several species.

Sioux County, Nebraska is in USDA Zone 5a. The average last spring frost is May 16 and the first fall frost is September 22, giving you a growing season of approximately 129 days.

At an elevation of 775 feet, Sioux County receives approximately 24.4 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Coreopsis to ensure they mature before fall.

Perennial Blooms in Summer Pollinator-friendly Deer-resistant Good for cutting
Sioux County, NE (Zone 5a) Short season
129 days
Last Spring Frost May 16
129 growing days
First Fall Frost September 22

Sioux County Soil Profile

Soil Type

Loam

Soil pH

6.3-7.2

Drainage

Well Drained

Coreopsis Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 9 Transplant: May 25 🌸 Bloom: Aug 3 – Nov 9
Recommended (50%) ✗ May not fit
Start indoors: Mar 14 Transplant: May 30 🌸 Bloom: Aug 8 – Nov 14
Safe Start (90%) ✗ May not fit
Start indoors: Apr 7 Transplant: Jun 23 🌸 Bloom: Sep 1 – Dec 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 Sioux County

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

Soil pH

Your soil pH (6.3–7.2) is within Coreopsis's preferred range (5.5–7.5).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.3%) — Coreopsis will thrive.

How to Plant Coreopsis

0.1"
Planting Depth
18"
Between Plants
24"
Between Rows

Succession Planting Coreopsis

2
successive plantings in your 129-day season

Sow every 6.9 weeks. Last sowing by Jul 04 to harvest before frost.

Coreopsis Water Budget

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

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Coreopsis

Coreopsis 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 Coreopsis Needs Rainfall You Supplement Action
Jan 1.7" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2.3" 0" ❄️ Dormant
Apr 2.5" 0" ❄️ Dormant
May 2.2" 2.7" 0" ✅ Rainfall sufficient
Jun 2.2" 1.6" 0.6" 💧 Light watering
Jul 2.2" 2" 0.2" 💧 Light watering
Aug 2.2" 2.8" 0" ✅ Rainfall sufficient
Sep 2.2" 2.2" 0" ✅ Rainfall sufficient
Oct 2.1" 0" ❄️ Dormant
Nov 1.6" 0" ❄️ Dormant
Dec 1.5" 0" ❄️ Dormant

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

Coreopsis 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.

Coreopsis needs ~910 GDD — county provides 1,677 GDD Excellent fit

Coreopsis Planting Timeline — Sioux County, NE

Coreopsis Planting Calendar

Activity When Date Range
Start Indoors March 14 Mar 14 – Mar 28
Transplant Outdoors May 30 May 30 – Jun 13
Direct Sow May 23 May 23 – Jun 13
Bloom August 8 Aug 8 – Nov 14

Plant 0.1" deep · 18" apart · Rows 24" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

60–80 days

🧪 Soil pH

Needs 5.5–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 5a

📆 Growing Season

129 days in Sioux County

Growing Tips for Coreopsis in Sioux County

Direct sow Coreopsis outdoors after May 16 in Sioux County when soil has warmed and frost danger has passed.

Common pests for Coreopsis in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.

Sioux County receives only 24" of rain annually. Coreopsis needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Start seeds indoors 8–10 weeks before last frost or direct sow after last frost. Seeds germinate easily without stratification. Thrives in poor to average, well-drained soil — rich soil promotes foliage over flowers. Drought tolerant once established; overwatering is the most common mistake. Deadhead spent blooms to maintain continuous flowering through the season. Shear plants by one-third in midsummer for a fresh flush of late-season blooms. Year 2+ plants bloom most heavily. Divide every 2–3 years in early spring to rejuvenate crowded clumps.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Coreopsis in Sioux County, NE?

Sioux County is in Zone 5a with an average last frost of May 16. Plan your Coreopsis planting based on this frost date — see the calendar above for exact timing.

What planting zone is Sioux County, NE?

Sioux County, Nebraska is in USDA Hardiness Zone 5a. The average last spring frost is May 16 and first fall frost is September 22.

🌱

Your Sioux County Garden Planner — Free

A 22-page printable planner built for Sioux 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 Sioux County, NE. Local conditions may vary. Last updated: July 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.