When to plant Calendula in Dover, IL
Spring Calendula in Dover goes in April 1–April 22, once nighttime temps stop dipping near freezing.
When to Plant Calendula in Dover, IL
Bureau County, Illinois gardeners: here's your June plan
Your garden in Bureau County, Illinois is working on a schedule, even when you're not. Here's where you should be this June.
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Fire up the seed-starting tray: calendula
These need a head start before your last frost (April 22). Sow into cells now so you're ready to transplant in a few weeks.
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Collect calendula at their peak
Morning harvests are best — cooler temperatures mean crisper produce and longer fridge life.
Coming up in July — start thinking about
- 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.
Dover, Illinois is in USDA Zone 5b. The average last spring frost is April 22 and the first fall frost is October 14, giving you a growing season of approximately 175 days.
At an elevation of 613 feet, Bureau County receives approximately 34.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Calendula to ensure they mature before fall.
Dover Soil Profile
Soil Type
Silt Loam
Soil pH
6.3-6.7
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 Dover
How your county's soil matches Calendula's growing requirements.
Soil pH
Your soil pH (6.3–6.7) is within Calendula's preferred range (5.5–7.0).
Soil Texture
The silt loam soil in Bureau County is excellent for Calendula — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.1%) — 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
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 | — | 1.6" | 0" | ❄️ Dormant |
| Mar | — | 2.2" | 0" | ❄️ Dormant |
| Apr | 2.2" | 3.2" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 4.4" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 4.7" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 4" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 3.3" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 2.8" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 2.7" | 0" | ✅ Rainfall sufficient |
| Nov | — | 2.6" | 0" | ❄️ Dormant |
| Dec | — | 1.7" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Bureau 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 — Dover, IL
Calendula Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 11 | Mar 11 – Mar 25 |
| Transplant Outdoors | April 22 | Apr 22 – May 6 |
| Direct Sow | April 1 | Apr 1 – Apr 22 |
| Bloom | June 10 | Jun 10 – Sep 9 |
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
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
175 days in Bureau County
Growing Tips for Calendula in Dover
Direct sow Calendula outdoors after April 22 in Bureau 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
When should I plant Calendula in Dover, IL?
In Dover, IL, plant Calendula after the last frost (around April 22) and before the first frost (around October 14). Best results when soil holds above 50°F.
What growing zone is Dover, IL for Calendula?
Dover sits in USDA Zone 5b. Calendula grows reliably in zones 2a through 11b, so it's a good fit here.
Can Calendula grow in Dover's climate?
Yes — Calendula grows well in Dover's temperate climate. Dover averages a 175-day frost-free season, with last frost around April 22 and first frost around October 14.
Your Bureau County Garden Planner — Free
A 22-page printable planner built for Bureau 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.