When to plant Calendula in Lyon County, IA
For Calendula in Lyon County, the safe spring window opens around April 11 and closes around May 2. Last expected frost is May 2, first fall frost October 2, giving a 153-day growing season.
When to Plant Calendula in Lyon County, IA
Your August gardening checklist
August rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Lyon County, Iowa.
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Pick calendula
The more you pick, the more the plant produces. Letting fruit overripen tells the plant it's time to stop.
Before September arrives, get these ready
- 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.
Lyon County, Iowa is in USDA Zone 5a. The average last spring frost is May 2 and the first fall frost is October 2, giving you a growing season of approximately 153 days.
At an elevation of 1,045 feet, Lyon County receives approximately 30.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Calendula to ensure they mature before fall.
Lyon County Soil Profile
Soil Type
Silt Loam
Soil pH
6.3-6.8
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 Lyon County
How your county's soil matches Calendula's growing requirements.
Soil pH
Your soil pH (6.3–6.8) is within Calendula's preferred range (5.5–7.0).
Soil Texture
The silt loam soil in Lyon County is excellent for Calendula — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.6%) — Calendula will thrive.
How to Plant Calendula
Succession Planting Calendula
Sow every 5.7 weeks. Last sowing by Jul 24 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 | — | 1.4" | 0" | ❄️ Dormant |
| Feb | — | 1.5" | 0" | ❄️ Dormant |
| Mar | — | 2" | 0" | ❄️ Dormant |
| Apr | — | 3.2" | 0" | ❄️ Dormant |
| May | 2.2" | 3" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 4.2" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 3.7" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 2.7" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 2.3" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 2.5" | 0" | ✅ Rainfall sufficient |
| Nov | — | 2.1" | 0" | ❄️ Dormant |
| Dec | — | 1.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in Lyon 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 — Lyon County, IA
Calendula Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 21 | Mar 21 – Apr 4 |
| Transplant Outdoors | May 2 | May 2 – May 16 |
| Direct Sow | April 11 | Apr 11 – May 2 |
| Bloom | June 20 | Jun 20 – Sep 12 |
Plant 0.3" deep · 9" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| 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 5a
📆 Growing Season
153 days in Lyon County
Growing Tips for Calendula in Lyon County
Direct sow Calendula outdoors after May 02 in Lyon 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 Lyon County, IA?
Lyon County is in Zone 5a with an average last frost of May 2. Plan your Calendula planting based on this frost date — see the calendar above for exact timing.
What planting zone is Lyon County, IA?
Lyon County, Iowa is in USDA Hardiness Zone 5a. The average last spring frost is May 2 and first fall frost is October 2.
When should I plant Calendula in Lyon County, IA?
In Lyon County, IA, plant Calendula after the last frost (around May 2) and before the first frost (around October 2). Best results when soil holds above 50°F.
What growing zone is Lyon County, IA for Calendula?
Lyon 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 Lyon County's climate?
Yes — Calendula grows well in Lyon County's temperate climate. Lyon County averages a 153-day frost-free season, with last frost around May 2 and first frost around October 2.
Your Lyon County Garden Planner — Free
A 22-page printable planner built for Lyon 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.