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When to plant Calendula in Hamilton County, KS

Hamilton County gardeners should plant Calendula between March 30 and April 20 in spring. With Hamilton County's Zone 6a climate (last frost April 27), Calendula needs 50–70 days to mature — plant by August 3 for a full harvest.

When to Plant Calendula in Hamilton County, KS

Hamilton County, Kansas Zone 6a August

August in Hamilton County, Kansas — your action list

August rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Hamilton County, Kansas.

Avg. last frost April 27
Avg. first frost October 12
Soil temp (4") 83°F
Watering High
Pest pressure High
Daylight 13.5 hrs
  1. Harvest calendula as they ripen

    Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.

Coming up in September — start thinking about
  • First harvests: calendula

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Calendula (Calendula officinalis) is a cheerful, edible-flowered cool-season annual valued by herbalists, chefs, and gardeners alike. Its golden-orange petals are used in salves, teas, and as a saffron substitute. Hardy enough to tolerate light frosts, it blooms prolifically in spring and fall, taking a pause during the hottest weeks of summer.

Hamilton County, Kansas is in USDA Zone 6a. The average last spring frost is April 27 and the first fall frost is October 12, giving you a growing season of approximately 168 days.

At an elevation of 871 feet, Hamilton County receives approximately 24 inches of rainfall annually with predominantly loam soil. Summer highs average 92°F, providing good warmth for Calendula during the growing season.

Annual Blooms in Multi-season Pollinator-friendly Deer-resistant Good for cutting Fragrant
Hamilton County, KS (Zone 6a) Moderate season
168 days
Last Spring Frost April 27
168 growing days
First Fall Frost October 12

Hamilton County Soil Profile

Soil Type

Loam

Soil pH

6.3-7.8

Drainage

Well Drained

Calendula Planting Risk Windows

Early Start (70% safe) ✓ Fits season (29 days to spare)
Start indoors: Mar 10 Transplant: Apr 21 🌸 Bloom: Jun 9 – Sep 8
Recommended (50%) ✓ Fits season (28 days to spare)
Start indoors: Mar 16 Transplant: Apr 27 🌸 Bloom: Jun 15 – Sep 14
Safe Start (90%) ✓ Fits season (29 days to spare)
Start indoors: Mar 31 Transplant: May 12 🌸 Bloom: Jun 30 – Sep 29

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 Hamilton County

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

Soil pH

Your soil pH (6.3–7.8) is more alkaline than Calendula prefers (5.5–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

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

How to Plant Calendula

0.3"
Planting Depth
9"
Between Plants
12"
Between Rows

Succession Planting Calendula

3
successive plantings in your 168-day season

Sow every 5.7 weeks. Last sowing by Aug 03 to harvest before frost.

Calendula Water Budget

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

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

Monthly Watering Guide for Calendula

Calendula 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 Calendula Needs Rainfall You Supplement Action
Jan 1.6" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 2.2" 2.8" 0" ✅ Rainfall sufficient
May 2.2" 3" 0" ✅ Rainfall sufficient
Jun 2.2" 1.5" 0.7" 💧 Light watering
Jul 2.2" 2.1" 0.1" 💧 Light watering
Aug 2.2" 2.6" 0" ✅ Rainfall sufficient
Sep 2.2" 1.7" 0.5" 💧 Light watering
Oct 2.2" 2" 0.2" 💧 Light watering
Nov 1.7" 0" ❄️ Dormant
Dec 1.4" 0" ❄️ Dormant

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

Calendula 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.

Calendula needs ~1,140 GDD — county provides 3,192 GDD Excellent fit

Calendula Planting Timeline — Hamilton County, KS

Calendula Planting Calendar

Activity When Date Range
Start Indoors March 16 Mar 16 – Mar 30
Transplant Outdoors April 27 Apr 27 – May 11
Direct Sow March 30 Mar 30 – Apr 20
Bloom June 15 Jun 15 – Sep 14

Plant 0.3" deep · 9" apart · Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

50–70 days

🧪 Soil pH

Needs 5.5–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 6a

📆 Growing Season

168 days in Hamilton County

Growing Tips for Calendula in Hamilton County

Direct sow Calendula outdoors after April 27 in Hamilton County when soil has warmed and frost danger has passed.

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

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

General growing tips

Direct-sow in early spring as soon as soil can be worked — seeds germinate in cool soil (50-65°F). In zones 7+, also sow in fall for winter/spring bloom. Deadhead consistently to extend bloom. Plants self-seed readily; save a few spent heads and allow them to drop. Harvest petals when flowers are fully open for best flavor and medicinal value.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Calendula in Hamilton County, KS?

Hamilton County is in Zone 6a with an average last frost of April 27. Plan your Calendula planting based on this frost date — see the calendar above for exact timing.

What planting zone is Hamilton County, KS?

Hamilton County, Kansas is in USDA Hardiness Zone 6a. The average last spring frost is April 27 and first fall frost is October 12.

When should I plant Calendula in Hamilton County, KS?

In Hamilton County, KS, plant Calendula after the last frost (around April 27) and before the first frost (around October 12). Best results when soil holds above 50°F.

What growing zone is Hamilton County, KS for Calendula?

Hamilton County sits in USDA Zone 6a. Calendula grows reliably in zones 2a through 11b, so it's a good fit here.

Can Calendula grow in Hamilton County's climate?

Yes — Calendula grows well in Hamilton County's temperate climate. Hamilton County averages a 168-day frost-free season, with last frost around April 27 and first frost around October 12.

🌱

Your Hamilton County Garden Planner — Free

A 22-page printable planner built for Hamilton County (Zone 6a). 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 Hamilton County, KS. Local conditions may vary. Last updated: August 2026.

Sources & credits

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