When to plant Calendula in Wapello County, IA
Aim to plant Calendula in Wapello County on or after March 31; the window stays open through April 21. Wapello County's 176-day frost-free season gives you a single solid spring crop with a brief fall option.
When to Plant Calendula in Wapello County, IA
June to-do list for Wapello County, Iowa
We've pulled the most time-sensitive tasks for Wapello County, Iowa this June and put them front and centre. Tackle them in order.
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Time to start calendula inside
Bottom-water once the first true leaves appear — it keeps stems dry and knocks back damping-off.
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Basket week: calendula
Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.
Get ahead of July
- First harvests: calendula
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.
Wapello County, Iowa is in USDA Zone 5b. The average last spring frost is April 21 and the first fall frost is October 14, giving you a growing season of approximately 176 days.
At an elevation of 670 feet, Wapello County receives approximately 34 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Calendula during the growing season.
Wapello County Soil Profile
Soil Type
Silt Loam
Soil pH
5.8-6.9
Drainage
Well Drained
Calendula Planting Risk Windows
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 Wapello County
How your county's soil matches Calendula's growing requirements.
Soil pH
Your soil pH (5.8–6.9) is within Calendula's preferred range (5.5–7.0).
Soil Texture
The silt loam soil in Wapello 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
Succession Planting Calendula
Sow every 5.7 weeks. Last sowing by Aug 05 to harvest before frost.
Calendula Water Budget
Water stress score is 6/10 — 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 | — | 1.2" | 0" | ❄️ Dormant |
| Feb | — | 1.7" | 0" | ❄️ Dormant |
| Mar | — | 2.5" | 0" | ❄️ Dormant |
| Apr | 2.2" | 3.6" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 3.5" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 4.3" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 3.8" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 3.7" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 3" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 2.6" | 0" | ✅ Rainfall sufficient |
| Nov | — | 2.4" | 0" | ❄️ Dormant |
| Dec | — | 1.6" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Wapello 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 Planting Timeline — Wapello County, IA
Calendula Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 10 | Mar 10 – Mar 24 |
| Transplant Outdoors | April 21 | Apr 21 – May 5 |
| Direct Sow | March 31 | Mar 31 – Apr 21 |
| Bloom | June 9 | Jun 9 – Sep 8 |
Plant 0.3" deep · 9" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| 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: ideal
🗺️ USDA Zone
Zone 5b
📆 Growing Season
176 days in Wapello County
Growing Tips for Calendula in Wapello County
Direct sow Calendula outdoors after April 21 in Wapello 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.
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 →
Calendula in Other Locations
Frequently Asked Questions
When should I plant Calendula in Wapello County, IA?
Wapello County is in Zone 5b with an average last frost of April 21. Plan your Calendula planting based on this frost date — see the calendar above for exact timing.
What planting zone is Wapello County, IA?
Wapello County, Iowa is in USDA Hardiness Zone 5b. The average last spring frost is April 21 and first fall frost is October 14.
When should I plant Calendula in Wapello County, IA?
In Wapello County, IA, plant Calendula after the last frost (around April 21) and before the first frost (around October 14). Best results when soil holds above 50°F.
What growing zone is Wapello County, IA for Calendula?
Wapello County sits in USDA Zone 5b. Calendula grows reliably in zones 2a through 11b, so it's a good fit here.
Can Calendula grow in Wapello County's climate?
Yes — Calendula grows well in Wapello County's temperate climate. Wapello County averages a 176-day frost-free season, with last frost around April 21 and first frost around October 14.
Your Wapello County Garden Planner — Free
A 22-page printable planner built for Wapello County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.