When to plant Geraniums in Boise County, ID
Boise County's 132-day season only supports one Geraniums planting per year. Sow between May 18 and June 1 for the best chance at full maturity before September 27.
When to Plant Geraniums in Boise County, ID
July to-do list for Boise County, Idaho
July is a pivotal month for Boise County, Idaho gardens. Focus on these tasks first and you'll set up the rest of the season for success.
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Begin indoor sowing: geraniums
These need a head start before your last frost (May 18). Sow into cells now so you're ready to transplant in a few weeks.
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Collect geraniums at their peak
This is the payoff month. Bring a basket, bring a friend, and get into the beds.
Coming up in August — start thinking about
- 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.
Boise County, Idaho is in USDA Zone 7a. The average last spring frost is May 18 and the first fall frost is September 27, giving you a growing season of approximately 132 days.
At an elevation of 8,023 feet, Boise County receives approximately 24.3 inches of rainfall annually with predominantly loam soil. Summer highs average 86°F, providing good warmth for Geraniums during the growing season.
Boise County Soil Profile
Soil Type
Loam
Soil pH
6.7-7.7
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 Boise County
How your county's soil matches Geraniums's growing requirements.
Soil pH
Your soil pH (6.7–7.7) is more alkaline than Geraniums prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Boise 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
Succession Planting Geraniums
Sow every 8 weeks. Last sowing by Jun 19 to harvest before frost.
Geraniums Water Budget
Water stress score is 8/10 — 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 | — | 1.8" | 0" | ❄️ Dormant |
| Feb | — | 1.4" | 0" | ❄️ Dormant |
| Mar | — | 2.1" | 0" | ❄️ Dormant |
| Apr | — | 2.4" | 0" | ❄️ Dormant |
| May | 4.3" | 3" | 1.3" | 💧 Light watering |
| Jun | 4.3" | 1.9" | 2.4" | 🚿 Regular watering |
| Jul | 4.3" | 1.8" | 2.5" | 🚿 Regular watering |
| Aug | 4.3" | 2.8" | 1.5" | 💧 Light watering |
| Sep | 4.3" | 1.7" | 2.6" | 🚿 Regular watering |
| Oct | — | 2.4" | 0" | ❄️ Dormant |
| Nov | — | 1.5" | 0" | ❄️ Dormant |
| Dec | — | 1.5" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Boise 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 — Boise County, ID
Geraniums Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 9 | Mar 9 – Mar 23 |
| Transplant Outdoors | May 18 | May 18 – Jun 1 |
| Bloom | July 27 | Jul 27 – Nov 16 |
Plant 0.1" deep · 12" apart · Rows 14" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | — |
| May | Transplant Outdoors |
| June | Transplant Outdoors |
| July | Bloom |
| August | Bloom |
| September | Bloom |
| October | Bloom |
| November | Bloom |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · Only during dry spells
📅 Days to Maturity
70–100 days
🧪 Soil pH
Needs 6–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 7a
📆 Growing Season
132 days in Boise County
Growing Tips for Geraniums in Boise County
Direct sow Geraniums outdoors after May 18 in Boise County when soil has warmed and frost danger has passed.
Boise County receives only 24" 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 Boise County, ID?
Boise County is in Zone 7a with an average last frost of May 18. Plan your Geraniums planting based on this frost date — see the calendar above for exact timing.
What planting zone is Boise County, ID?
Boise County, Idaho is in USDA Hardiness Zone 7a. The average last spring frost is May 18 and first fall frost is September 27.
When should I plant Geraniums in Boise County, ID?
In Boise County, ID, plant Geraniums after the last frost (around May 18) and before the first frost (around September 27). Best results when soil holds above 50°F.
What growing zone is Boise County, ID for Geraniums?
Boise 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 Boise County's climate?
Yes — Geraniums grows well in Boise County's temperate climate. Boise County averages a 132-day frost-free season, with last frost around May 18 and first frost around September 27.
Your Boise County Garden Planner — Free
A 22-page printable planner built for Boise 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.