When to plant Geraniums in St. Louis County, MO
St. Louis County sits in cold Zone 7a. Plant Geraniums April 13–April 27 for the single annual harvest; the October 24 first frost closes the window.
When to Plant Geraniums in St. Louis County, MO
Geraniums (Pelargonium × hortorum) are tender perennials grown as warm-season annuals throughout North America. Prized for their bold flower clusters, long bloom period, and tolerance of summer heat when planted in well-drained soil, they anchor window boxes, containers, and bed borders from late spring until hard frost. Zones 9b–11b can overwinter plants in the ground.
St. Louis County, Missouri is in USDA Zone 7a. The average last spring frost is April 13 and the first fall frost is October 24, giving you a growing season of approximately 194 days.
At an elevation of 895 feet, St. Louis County receives approximately 40.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Geraniums during the growing season.
St. Louis County Soil Profile
Soil Type
Silt Loam
Soil pH
6.0-7.0
Drainage
Well Drained
Geraniums Planting Timeline — St. Louis County, MO
Geraniums Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 2 | Feb 2 – Feb 16 |
| Transplant Outdoors | April 13 | Apr 13 – Apr 27 |
| Bloom | June 22 | Jun 22 – Oct 12 |
Plant 0.1" deep · 12" apart · Rows 14" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | — |
| April | Transplant Outdoors |
| May | — |
| June | Bloom |
| July | Bloom |
| August | Bloom |
| September | Bloom |
| October | Bloom |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
Moderate — regular watering
📅 Days to Maturity
70–100 days
🧪 Soil pH
Needs 6–7 · Your soil: N/A
🗺️ USDA Zone
Zone 7a
📆 Growing Season
194 days in St. Louis County
Growing Tips for St. Louis County
Start seeds indoors 10–12 weeks before last frost — germination is slow and erratic without bottom heat (70–75°F). Transplant after frost danger passes. Geraniums rarely direct-sown; cuttings or transplants are the standard. Deadhead spent umbels weekly to maintain continuous bloom. Let soil dry slightly between waterings to prevent root rot. In zones 10–11 plants may be left in ground year-round or overwintered as houseplants.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Geraniums in Other Locations
Frequently Asked Questions
When should I plant Geraniums in St. Louis County, MO?
St. Louis County is in Zone 7a with an average last frost of April 13. Plan your Geraniums planting based on this frost date — see the calendar above for exact timing.
What planting zone is St. Louis County, MO?
St. Louis County, Missouri is in USDA Hardiness Zone 7a. The average last spring frost is April 13 and first fall frost is October 24.
When should I plant Geraniums in St. Louis County, MO?
In St. Louis County, MO, plant Geraniums after the last frost (around April 13) and before the first frost (around October 24). Best results when soil holds above 50°F.
What growing zone is St. Louis County, MO for Geraniums?
St. Louis County sits in USDA Zone 7a. Geraniums grows reliably in zones 2a through 11b, so it's a good fit here.
Can Geraniums grow in St. Louis County's climate?
Yes — Geraniums grows well in St. Louis County's temperate climate. St. Louis County averages a 194-day frost-free season, with last frost around April 13 and first frost around October 24.
Your St. Louis County Garden Planner — Free
A 22-page printable planner built for St. Louis County (Zone 7a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.