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When to plant Coreopsis in Middlesex County, CT

Spring Coreopsis in Middlesex County goes in April 18–May 9, once nighttime temps stop dipping near freezing.

When to Plant Coreopsis in Middlesex County, CT

Middlesex County, Connecticut Zone 6b July

Middlesex County, Connecticut gardeners: here's your July plan

If you only do a handful of things in the garden this July, make it these. They're sequenced around your zone's frost timing.

Avg. last frost April 18
Avg. first frost October 26
Soil temp (4") 79°F
Watering Moderate
Pest pressure High
Daylight 14.7 hrs
  1. Harvest coreopsis as they ripen

    This is the payoff month. Bring a basket, bring a friend, and get into the beds.

To set up a strong August, finish these tasks
  • 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.

Middlesex County, Connecticut is in USDA Zone 6b. The average last spring frost is April 18 and the first fall frost is October 26, giving you a growing season of approximately 191 days.

At an elevation of 248 feet, Middlesex County receives approximately 40.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Coreopsis during the growing season.

Perennial Blooms in Summer Pollinator-friendly Deer-resistant Good for cutting
Middlesex County, CT (Zone 6b) Moderate season
191 days
Last Spring Frost April 18
191 growing days
First Fall Frost October 26

Middlesex County Soil Profile

Soil Type

Silt Loam

Soil pH

5.2-6.2

Drainage

Well Drained

Coreopsis Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Feb 7 Transplant: Apr 18 🌸 Bloom: Jun 27 – Oct 24
Recommended (50%) ✗ May not fit
Start indoors: Feb 14 Transplant: Apr 25 🌸 Bloom: Jul 4 – Oct 31
Safe Start (90%) ✗ May not fit
Start indoors: Mar 4 Transplant: May 13 🌸 Bloom: Jul 22 – Nov 18

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 Middlesex County

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

Soil pH

Your soil pH (5.2–6.2) overlaps with Coreopsis's range (5.5–7.5), though not a perfect match.

Soil Texture

The silt loam soil in Middlesex 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

3
successive plantings in your 191-day season

Sow every 6.9 weeks. Last sowing by Aug 07 to harvest before frost.

Coreopsis Water Budget

Plant needs
0.5″/week
Rainfall provides
0.9″/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 3.2" 0" ❄️ Dormant
Feb 3" 0" ❄️ Dormant
Mar 3.7" 0" ❄️ Dormant
Apr 2.2" 3.6" 0" ✅ Rainfall sufficient
May 2.2" 3.9" 0" ✅ Rainfall sufficient
Jun 2.2" 4.3" 0" ✅ Rainfall sufficient
Jul 2.2" 3.4" 0" ✅ Rainfall sufficient
Aug 2.2" 3.8" 0" ✅ Rainfall sufficient
Sep 2.2" 3" 0" ✅ Rainfall sufficient
Oct 2.2" 3" 0" ✅ Rainfall sufficient
Nov 2.8" 0" ❄️ Dormant
Dec 2.8" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Middlesex 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 ~1,225 GDD — county provides 3,342 GDD Excellent fit

Coreopsis Planting Timeline — Middlesex County, CT

Coreopsis Planting Calendar

Activity When Date Range
Start Indoors February 14 Feb 14 – Feb 28
Transplant Outdoors April 25 Apr 25 – May 9
Direct Sow April 18 Apr 18 – May 9
Bloom July 4 Jul 4 – Oct 31

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

Month-by-Month Timeline

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

60–80 days

🧪 Soil pH

Needs 5.5–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 6b

📆 Growing Season

191 days in Middlesex County

Growing Tips for Coreopsis in Middlesex County

Direct sow Coreopsis outdoors after April 18 in Middlesex 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 Middlesex County, CT?

Middlesex County is in Zone 6b with an average last frost of April 18. Plan your Coreopsis planting based on this frost date — see the calendar above for exact timing.

What planting zone is Middlesex County, CT?

Middlesex County, Connecticut is in USDA Hardiness Zone 6b. The average last spring frost is April 18 and first fall frost is October 26.

When should I plant Coreopsis in Middlesex County, CT?

In Middlesex County, CT, plant Coreopsis after the last frost (around April 18) and before the first frost (around October 26). Best results when soil holds above 50°F.

What growing zone is Middlesex County, CT for Coreopsis?

Middlesex County sits in USDA Zone 6b. Coreopsis grows reliably in zones 3a through 9b, so it's a good fit here.

Can Coreopsis grow in Middlesex County's climate?

Yes — Coreopsis grows well in Middlesex County's temperate climate. Middlesex County averages a 191-day frost-free season, with last frost around April 18 and first frost around October 26.

🌱

Your Middlesex County Garden Planner — Free

A 22-page printable planner built for Middlesex County (Zone 6b). 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 Middlesex County, CT. 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.