When to plant Geraniums in Isleton, CA
Isleton's 293-day season only supports one Geraniums planting per year. Sow between January 15 and January 29 for the best chance at full maturity before December 1.
When to Plant Geraniums in Isleton, CA
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.
Isleton, California is in USDA Zone 9b. The average last spring frost is February 12 and the first fall frost is December 1, giving you a growing season of approximately 292 days.
At an elevation of 263 feet, Sacramento County receives approximately 33.2 inches of rainfall annually with predominantly loam soil. Summer highs average 90°F, providing good warmth for Geraniums during the growing season.
Isleton Soil Profile
Soil Type
Loam
Soil pH
6.4-7.1
Drainage
Well Drained
Monthly Watering Guide for Geraniums
Geraniums needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Geraniums Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 6.1" | 0" | ❄️ Dormant |
| Feb | 4.3" | 7.5" | 0" | ✅ Rainfall sufficient |
| Mar | 4.3" | 5.7" | 0" | ✅ Rainfall sufficient |
| Apr | 4.3" | 2.5" | 1.8" | 💧 Light watering |
| May | 4.3" | 0.8" | 3.5" | 🚿 Regular watering |
| Jun | 4.3" | 0.2" | 4.1" | 🚿 Regular watering |
| Jul | 4.3" | 0" | 4.3" | 🚿 Regular watering |
| Aug | 4.3" | 0" | 4.3" | 🚿 Regular watering |
| Sep | 4.3" | 0.3" | 4" | 🚿 Regular watering |
| Oct | 4.3" | 1.4" | 2.9" | 🚿 Regular watering |
| Nov | 4.3" | 2.7" | 1.6" | 💧 Light watering |
| Dec | 4.3" | 5.9" | 0" | ✅ Rainfall sufficient |
Water needs are for active growing months only (Feb–Dec in Sacramento County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Geraniums Planting Timeline — Isleton, CA
Geraniums Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | December 4 | Dec 4 – Dec 18 |
| Transplant Outdoors | January 15 | Jan 15 – Jan 29 |
| Bloom | March 26 | Mar 26 – Oct 8 |
Plant 0.1" deep · 12" apart · Rows 14" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Transplant Outdoors |
| February | — |
| March | Bloom |
| April | Bloom |
| May | Bloom |
| June | Bloom |
| July | Bloom |
| August | Bloom |
| September | Bloom |
| October | Bloom |
| November | — |
| December | Start Indoors |
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 9b
📆 Growing Season
292 days in Sacramento County
Growing Tips for Isleton
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
When should I plant Geraniums in Isleton, CA?
In Isleton, CA, plant Geraniums after the last frost (around February 12) and before the first frost (around December 1). Best results when soil holds above 50°F.
What growing zone is Isleton, CA for Geraniums?
Isleton sits in USDA Zone 9b. Geraniums grows reliably in zones 2a through 11b, so it's a good fit here.
Can Geraniums grow in Isleton's climate?
Yes — Geraniums grows well in Isleton's temperate climate. Isleton averages a 293-day frost-free season, with last frost around February 12 and first frost around December 1.
Your Sacramento County Garden Planner — Free
A 22-page printable planner built for Sacramento County (Zone 9b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.