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When to plant Geraniums in Alamosa County County,
Alamosa County County's short 111-day growing season means one Geraniums planting between June 7 and June 21. No fall crop in Zone 5a.
When to Plant Geraniums in Alamosa County, CO
Top priorities for Alamosa County, Colorado gardeners in June
Your Alamosa County, Colorado garden is entering a new phase. Here's what's on the schedule for June and why each task matters now.
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Plant out geraniums
Frost risk is low now in Alamosa County, Colorado. If you've been covering beds overnight, you can stop.
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.
Alamosa County, Colorado is in USDA Zone 5a. The average last spring frost is May 31 and the first fall frost is September 19, giving you a growing season of approximately 111 days.
At an elevation of 8,366 feet, Alamosa County receives approximately 18.3 inches of rainfall annually with predominantly loam soil. Summer highs average 81°F, so choose short-season varieties of Geraniums to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Geraniums successfully. Mulch heavily to conserve soil moisture.
Alamosa County Soil Profile
Soil Type
Loam
Soil pH
6.4-8
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 Alamosa County
How your county's soil matches Geraniums's growing requirements.
Soil pH
Your soil pH (6.4–8.0) is more alkaline than Geraniums prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Alamosa County is excellent for Geraniums — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.3%). Annual compost additions will help Geraniums.
How to Plant Geraniums
Geraniums Water Budget
Water stress score is 6/10 — 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 | — | 1.3" | 0" | ❄️ Dormant |
| Feb | — | 1.1" | 0" | ❄️ Dormant |
| Mar | — | 1.5" | 0" | ❄️ Dormant |
| Apr | — | 1.9" | 0" | ❄️ Dormant |
| May | 4.3" | 2" | 2.3" | 🚿 Regular watering |
| Jun | 4.3" | 1.5" | 2.8" | 🚿 Regular watering |
| Jul | 4.3" | 1.5" | 2.8" | 🚿 Regular watering |
| Aug | 4.3" | 1.9" | 2.4" | 🚿 Regular watering |
| Sep | 4.3" | 1.4" | 2.9" | 🚿 Regular watering |
| Oct | — | 1.6" | 0" | ❄️ Dormant |
| Nov | — | 1.6" | 0" | ❄️ Dormant |
| Dec | — | 1" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Alamosa 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 — Alamosa County, CO
Geraniums Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 22 | Mar 22 – Apr 5 |
| Transplant Outdoors | June 7 | Jun 7 – Jun 21 |
| Bloom | August 16 | Aug 16 – Nov 8 |
Plant 0.1" deep · 12" apart · Rows 14" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors |
| May | — |
| June | Transplant Outdoors |
| July | — |
| August | Bloom |
| September | Bloom |
| October | Bloom |
| November | Bloom |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · 1-2 times/week
📅 Days to Maturity
70–100 days
🧪 Soil pH
Needs 6–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 5a
📆 Growing Season
111 days in Alamosa County
Growing Tips for Geraniums in Alamosa County
Direct sow Geraniums outdoors after May 31 in Alamosa County when soil has warmed and frost danger has passed.
Your 111.0-day growing season in Alamosa County is tight for Geraniums (70.0-100.0 days to maturity). Start indoors and choose early-maturing varieties.
Alamosa County receives only 18" 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 Alamosa County, CO?
Alamosa County is in Zone 5a with an average last frost of May 31. Plan your Geraniums planting based on this frost date — see the calendar above for exact timing.
What planting zone is Alamosa County, CO?
Alamosa County, Colorado is in USDA Hardiness Zone 5a. The average last spring frost is May 31 and first fall frost is September 19.
When should I plant Geraniums in Alamosa County, ?
In Alamosa County, , plant Geraniums after the last frost (around May 31) and before the first frost (around September 19). Best results when soil holds above 50°F.
What growing zone is Alamosa County, for Geraniums?
Alamosa County sits in USDA Zone 5a. Geraniums grows reliably in zones 2a through 11b, so it's a good fit here.
Can Geraniums grow in Alamosa County's climate?
Yes — Geraniums grows well in Alamosa County's temperate climate. Alamosa County averages a 111-day frost-free season, with last frost around May 31 and first frost around September 19.
Your Alamosa County Garden Planner — Free
A 22-page printable planner built for Alamosa County (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.