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When to plant Coreopsis in Koochiching County, MN

Koochiching County's 119-day season only supports one Coreopsis planting per year. Sow between May 29 and June 19 for the best chance at full maturity before September 18.

When to Plant Coreopsis in Koochiching County, MN

Koochiching County, Minnesota Zone 3b June

June in the garden — Koochiching County, Minnesota

Your garden in Koochiching County, Minnesota is working on a schedule, even when you're not. Here's where you should be this June.

Avg. last frost May 22
Avg. first frost September 18
Soil temp (4") 61°F
Watering Low
Pest pressure Moderate
Daylight 15.8 hrs
  1. Move coreopsis from tray to bed

    Frost risk is low now in Koochiching County, Minnesota. If you've been covering beds overnight, you can stop.

Get ahead of July
  • Starting indoors: 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.

Koochiching County, Minnesota is in USDA Zone 3b. The average last spring frost is May 22 and the first fall frost is September 18, giving you a growing season of approximately 119 days.

At an elevation of 508 feet, Koochiching County receives approximately 41.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 79°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
Koochiching County, MN (Zone 3b) Short season
119 days
Last Spring Frost May 22
119 growing days
First Fall Frost September 18

Koochiching County Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-7.2

Drainage

Well Drained

Coreopsis Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 7 Transplant: May 30 🌸 Bloom: Aug 22 – Oct 24
Recommended (50%) ✗ May not fit
Start indoors: Mar 13 Transplant: Jun 5 🌸 Bloom: Aug 28 – Oct 30
Safe Start (90%) ✗ May not fit
Start indoors: Apr 6 Transplant: Jun 29 🌸 Bloom: Sep 21 – Nov 23

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 Koochiching County

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

Soil pH

Your soil pH (5.8–7.2) is within Coreopsis's preferred range (5.5–7.5).

Soil Texture

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

Organic Matter

Organic matter is moderate (3.8%). Annual compost additions will help Coreopsis.

How to Plant Coreopsis

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

Succession Planting Coreopsis

2
successive plantings in your 119-day season

Sow every 6.9 weeks. Last sowing by Jun 30 to harvest before frost.

Coreopsis Water Budget

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

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 1.5" 0" ❄️ Dormant
Feb 2" 0" ❄️ Dormant
Mar 3" 0" ❄️ Dormant
Apr 4" 0" ❄️ Dormant
May 2.2" 5" 0" ✅ Rainfall sufficient
Jun 2.2" 5" 0" ✅ Rainfall sufficient
Jul 2.2" 5" 0" ✅ Rainfall sufficient
Aug 2.2" 3.8" 0" ✅ Rainfall sufficient
Sep 2.2" 3.7" 0" ✅ Rainfall sufficient
Oct 2.8" 0" ❄️ Dormant
Nov 3.2" 0" ❄️ Dormant
Dec 2.4" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Koochiching 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 ~648 GDD — county provides 1,100 GDD Excellent fit

Coreopsis Planting Timeline — Koochiching County, MN

Coreopsis Planting Calendar

Activity When Date Range
Start Indoors March 13 Mar 13 – Mar 27
Transplant Outdoors June 5 Jun 5 – Jun 19
Direct Sow May 29 May 29 – Jun 19
Bloom August 28 Aug 28 – Oct 30

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

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April
May Direct Sow
June Transplant Outdoors Direct Sow
July
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

60–80 days

🧪 Soil pH

Needs 5.5–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 3b

📆 Growing Season

119 days in Koochiching County

Growing Tips for Coreopsis in Koochiching County

Direct sow Coreopsis outdoors after May 22 in Koochiching 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.

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 Koochiching County, MN?

Koochiching County is in Zone 3b with an average last frost of May 22. Plan your Coreopsis planting based on this frost date — see the calendar above for exact timing.

What planting zone is Koochiching County, MN?

Koochiching County, Minnesota is in USDA Hardiness Zone 3b. The average last spring frost is May 22 and first fall frost is September 18.

When should I plant Coreopsis in Koochiching County, MN?

In Koochiching County, MN, plant Coreopsis after the last frost (around May 22) and before the first frost (around September 18). Best results when soil holds above 50°F.

What growing zone is Koochiching County, MN for Coreopsis?

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

Can Coreopsis grow in Koochiching County's climate?

Yes — Coreopsis grows well in Koochiching County's temperate climate. Koochiching County averages a 119-day frost-free season, with last frost around May 22 and first frost around September 18.

🌱

Your Koochiching County Garden Planner — Free

A 22-page printable planner built for Koochiching County (Zone 3b). 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 Koochiching County, MN. Local conditions may vary. Last updated: June 2026.

Sources & credits

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