When to plant Marigolds in St. Clair County, MO
Aim to plant Marigolds in St. Clair County on or after April 8; the window stays open through April 29. St. Clair County's 201-day frost-free season gives you enough for a full main crop and a short fall succession.
When to Plant Marigolds in St. Clair County, MO
Marigolds (Tagetes patula) are warm-season annuals beloved for their cheerful orange, yellow, and red blooms — and for their well-documented ability to repel pest nematodes in vegetable beds. Easy from seed, drought-tolerant once established, and bloom from early summer until the first hard frost.
St. Clair County, Missouri is in USDA Zone 6b. The average last spring frost is April 8 and the first fall frost is October 26, giving you a growing season of approximately 201 days.
At an elevation of 699 feet, St. Clair County receives approximately 41.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Marigolds during the growing season.
St. Clair County Soil Profile
Soil Type
Silt Loam
Soil pH
6.0-7.0
Drainage
Well Drained
Marigolds Planting Timeline — St. Clair County, MO
Marigolds Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 25 | Feb 25 – Mar 11 |
| Transplant Outdoors | April 8 | Apr 8 – Apr 22 |
| Direct Sow | April 8 | Apr 8 – Apr 29 |
| Bloom | June 3 | Jun 3 – Sep 9 |
Plant 0.3" deep · 10" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Start Indoors |
| April | Transplant Outdoors Direct Sow |
| May | — |
| 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 6–7.5 · Your soil: N/A
🗺️ USDA Zone
Zone 6b
📆 Growing Season
201 days in St. Clair County
Growing Tips for St. Clair County
Direct-sow after last frost or start indoors 4-6 weeks earlier. Deadhead spent blooms to keep new flowers coming. French marigolds (T. patula) are the most reliable nematode repellents — plant a band around vegetable beds. Tolerate poor soil but bloom best with monthly compost.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Very easy to save. Seeds are the long, thin, dark pieces inside the dried flower head.
Marigolds in Other Locations
Frequently Asked Questions
When should I plant Marigolds in St. Clair County, MO?
St. Clair County is in Zone 6b with an average last frost of April 8. Plan your Marigolds planting based on this frost date — see the calendar above for exact timing.
What planting zone is St. Clair County, MO?
St. Clair County, Missouri is in USDA Hardiness Zone 6b. The average last spring frost is April 8 and first fall frost is October 26.
When should I plant Marigolds in St. Clair County, MO?
In St. Clair County, MO, plant Marigolds after the last frost (around April 8) and before the first frost (around October 26). Best results when soil holds above 50°F.
What growing zone is St. Clair County, MO for Marigolds?
St. Clair County sits in USDA Zone 6b. Marigolds grows reliably in zones 2a through 11b, so it's a good fit here.
Can Marigolds grow in St. Clair County's climate?
Yes — Marigolds grows well in St. Clair County's temperate climate. St. Clair County averages a 201-day frost-free season, with last frost around April 8 and first frost around October 26.
Your St. Clair County Garden Planner — Free
A 22-page printable planner built for St. Clair County (Zone 6b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.