When to plant Geraniums in Pima County, AZ
Pima County's short 222-day growing season means one Geraniums planting between March 4 and March 18. No fall crop in Zone 9b.
When to Plant Geraniums in Pima County, AZ
July in Pima County, Arizona — your action list
If you only do a handful of things in the garden this July, make it these. They're sequenced around your zone's frost timing.
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Basket week: geraniums
If you can't use it all right away, check the food-preservation section of your planner.
August will be here before you know it — start on
- First harvests: geraniums
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.
Pima County, Arizona is in USDA Zone 9b. The average last spring frost is April 1 and the first fall frost is November 9, giving you a growing season of approximately 222 days.
At an elevation of 4,327 feet, Pima County receives approximately 14.4 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 103°F, so Geraniums may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Geraniums will need more frequent watering and organic matter to retain nutrients. With low rainfall, drip irrigation is essential for growing Geraniums successfully. Mulch heavily to conserve soil moisture.
Pima County Soil Profile
Soil Type
Sandy Loam
Soil pH
6.8-8.3
Drainage
Well Drained
Geraniums 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 Pima County
How your county's soil matches Geraniums's growing requirements.
Soil pH
Your soil pH (6.8–8.3) is more alkaline than Geraniums prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
Sandy soil in Pima County warms quickly in spring but drains fast. Geraniums will need more frequent watering and regular compost additions to retain nutrients.
Drainage
Drainage is adequate for Geraniums.
Organic Matter
Organic matter is low (0.9%). Add 2-3 inches of compost before planting Geraniums.
How to Plant Geraniums
Succession Planting Geraniums
Sow every 8 weeks. Last sowing by Aug 01 to harvest before frost.
Geraniums Water Budget
Water stress score is 10/10 — consider drought-tolerant varieties and mulching
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 | — | 0.9" | 0" | ❄️ Dormant |
| Feb | — | 0.8" | 0" | ❄️ Dormant |
| Mar | — | 0.7" | 0" | ❄️ Dormant |
| Apr | 4.3" | 0.5" | 3.8" | 🚿 Regular watering |
| May | 4.3" | 0.4" | 3.9" | 🚿 Regular watering |
| Jun | 4.3" | 0.5" | 3.8" | 🚿 Regular watering |
| Jul | 4.3" | 2.7" | 1.6" | 💧 Light watering |
| Aug | 4.3" | 3.2" | 1.1" | 💧 Light watering |
| Sep | 4.3" | 1.9" | 2.4" | 🚿 Regular watering |
| Oct | 4.3" | 1.4" | 2.9" | 🚿 Regular watering |
| Nov | 4.3" | 0.7" | 3.6" | 🚿 Regular watering |
| Dec | — | 0.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Nov in Pima County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Geraniums 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.
Geraniums Planting Timeline — Pima County, AZ
Geraniums Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | January 21 | Jan 21 – Feb 4 |
| Transplant Outdoors | March 4 | Mar 4 – Mar 18 |
| Bloom | May 13 | May 13 – Nov 25 |
Plant 0.1" deep · 12" apart · Rows 14" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Start Indoors |
| February | Start Indoors |
| March | Transplant Outdoors |
| April | — |
| May | Bloom |
| June | Bloom |
| July | Bloom |
| August | Bloom |
| September | Bloom |
| October | Bloom |
| November | Bloom |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · 2-3 times/week
📅 Days to Maturity
70–100 days
🧪 Soil pH
Needs 6–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 9b
📆 Growing Season
222 days in Pima County
Growing Tips for Geraniums in Pima County
Direct sow Geraniums outdoors after April 01 in Pima County when soil has warmed and frost danger has passed.
Sandy soil in Pima County dries quickly — mulch Geraniums with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.
With summer highs reaching 103°F in Pima County, provide afternoon shade for Geraniums and water deeply in the morning.
Pima County receives only 14" of rain annually. Geraniums needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
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 Pima County, AZ?
Pima County is in Zone 9b with an average last frost of April 1. Plan your Geraniums planting based on this frost date — see the calendar above for exact timing.
What planting zone is Pima County, AZ?
Pima County, Arizona is in USDA Hardiness Zone 9b. The average last spring frost is April 1 and first fall frost is November 9.
When should I plant Geraniums in Pima County, AZ?
In Pima County, AZ, plant Geraniums after the last frost (around April 1) and before the first frost (around November 9). Best results when soil holds above 50°F.
What growing zone is Pima County, AZ for Geraniums?
Pima County sits in USDA Zone 9b. Geraniums grows reliably in zones 2a through 11b, so it's a good fit here.
Can Geraniums grow in Pima County's climate?
Yes — Geraniums grows well in Pima County's temperate climate. Pima County averages a 222-day frost-free season, with last frost around April 1 and first frost around November 9.
Your Pima County Garden Planner — Free
A 22-page printable planner built for Pima 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.