When to plant Calendula in Hardin County, IA
Spring Calendula in Hardin County goes in April 7–April 28, once nighttime temps stop dipping near freezing.
When to Plant Calendula in Hardin County, IA
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.
Hardin County, Iowa is in USDA Zone 5a. The average last spring frost is April 28 and the first fall frost is October 9, giving you a growing season of approximately 164 days.
At an elevation of 507 feet, Hardin County receives approximately 40.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Calendula to ensure they mature before fall.
Hardin County Soil Profile
Soil Type
Silt Loam
Soil pH
6.0-7.0
Drainage
Well Drained
Calendula Planting Timeline — Hardin County, IA
Calendula Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 17 | Mar 17 – Mar 31 |
| Transplant Outdoors | April 28 | Apr 28 – May 12 |
| Direct Sow | April 7 | Apr 7 – Apr 28 |
| Bloom | June 16 | Jun 16 – Sep 8 |
Plant 0.3" deep · 9" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| 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
Low — drought tolerant
📅 Days to Maturity
50–70 days
🧪 Soil pH
Needs 5.5–7 · Your soil: N/A
🗺️ USDA Zone
Zone 5a
📆 Growing Season
164 days in Hardin County
Growing Tips for Hardin County
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 →
Calendula in Other Locations
Frequently Asked Questions
When should I plant Calendula in Hardin County, IA?
Hardin County is in Zone 5a with an average last frost of April 28. Plan your Calendula planting based on this frost date — see the calendar above for exact timing.
What planting zone is Hardin County, IA?
Hardin County, Iowa is in USDA Hardiness Zone 5a. The average last spring frost is April 28 and first fall frost is October 9.
When should I plant Calendula in Hardin County, IA?
In Hardin County, IA, plant Calendula after the last frost (around April 28) and before the first frost (around October 9). Best results when soil holds above 50°F.
What growing zone is Hardin County, IA for Calendula?
Hardin County sits in USDA Zone 5a. Calendula grows reliably in zones 2a through 11b, so it's a good fit here.
Can Calendula grow in Hardin County's climate?
Yes — Calendula grows well in Hardin County's temperate climate. Hardin County averages a 164-day frost-free season, with last frost around April 28 and first frost around October 9.
Your Hardin County Garden Planner — Free
A 22-page printable planner built for Hardin 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.