When to plant Nasturtium in Custer County, ID
Plant Nasturtium in Custer County, between June 25 and July 16 — the only viable window. Zone 5b's short season (79 frost-free days) rules out a fall crop.
When to Plant Nasturtium in Custer County, ID
What to do in July
July rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Custer County, Idaho.
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Fire up the seed-starting tray: nasturtium
You're about 8 weeks out from your last frost — the perfect window to get these germinating indoors.
To set up a strong August, finish these tasks
- First harvests: nasturtium
Nasturtium (Tropaeolum majus) is a fast-growing annual with distinctive round, lily-pad leaves and bold trumpet-shaped blooms in warm oranges, reds, and yellows. Both the flowers and leaves are edible with a peppery watercress flavor. Planted near vegetables, nasturtiums act as a sacrifice trap-crop, luring aphids away from more valuable plants. They thrive in poor, dry soil — rich conditions produce lush foliage but few flowers.
Custer County, Idaho is in USDA Zone 5b. The average last spring frost is June 18 and the first fall frost is September 5, giving you a growing season of approximately 79 days.
At an elevation of 5,189 feet, Custer County receives approximately 20.6 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Nasturtium to ensure they mature before fall.
Custer County Soil Profile
Soil Type
Loam
Soil pH
6.3-8
Drainage
Well Drained
Nasturtium 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 Custer County
How your county's soil matches Nasturtium's growing requirements.
Soil pH
Your soil pH (6.3–8.0) is within Nasturtium's preferred range (6.0–8.0).
Soil Texture
The loam soil in Custer County is excellent for Nasturtium — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.3%). Annual compost additions will help Nasturtium.
How to Plant Nasturtium
Nasturtium Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Nasturtium
Nasturtium needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.
| Month | Nasturtium Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.3" | 0" | ❄️ Dormant |
| Feb | — | 1.3" | 0" | ❄️ Dormant |
| Mar | — | 1.7" | 0" | ❄️ Dormant |
| Apr | — | 2.4" | 0" | ❄️ Dormant |
| May | — | 2.3" | 0" | ❄️ Dormant |
| Jun | 2.2" | 1.5" | 0.7" | 💧 Light watering |
| Jul | 2.2" | 2" | 0.2" | 💧 Light watering |
| Aug | 2.2" | 2.1" | 0.1" | 💧 Light watering |
| Sep | 2.2" | 1.7" | 0.5" | 💧 Light watering |
| Oct | — | 1.6" | 0" | ❄️ Dormant |
| Nov | — | 1.4" | 0" | ❄️ Dormant |
| Dec | — | 1.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Jun–Sep in Custer County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Nasturtium 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.
Nasturtium Planting Timeline — Custer County, ID
Nasturtium Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | May 21 | May 21 – Jun 4 |
| Transplant Outdoors | June 25 | Jun 25 – Jul 9 |
| Direct Sow | June 25 | Jun 25 – Jul 16 |
| Bloom | August 20 | Aug 20 – Dec 3 |
Plant 0.5" deep · 10" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Start Indoors |
| June | Start Indoors Transplant Outdoors Direct Sow |
| July | Transplant Outdoors Direct Sow |
| August | Bloom |
| September | Bloom |
| October | Bloom |
| November | Bloom |
| December | Bloom |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Natural rainfall sufficient
📅 Days to Maturity
55–65 days
🧪 Soil pH
Needs 6–8 · Your soil: ideal
🗺️ USDA Zone
Zone 5b
📆 Growing Season
79 days in Custer County
Growing Tips for Nasturtium in Custer County
Direct sow Nasturtium outdoors after June 18 in Custer County when soil has warmed and frost danger has passed.
Custer County receives only 21" of rain annually. Nasturtium needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Direct-sow large seeds 1/2 inch deep after last frost; soak seeds overnight to speed germination (7-10 days). Nasturtiums dislike root disturbance so direct sowing is strongly preferred. Avoid fertilizing — poor soil brings the best bloom. Trailing types can cover banks and climb trellises; dwarf types suit containers. In hot climates (zones 9+) plant in fall for winter/spring bloom as plants struggle in peak summer heat.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Nasturtium in Other Locations
Frequently Asked Questions
When should I plant Nasturtium in Custer County, ID?
Custer County is in Zone 5b with an average last frost of June 18. Plan your Nasturtium planting based on this frost date — see the calendar above for exact timing.
What planting zone is Custer County, ID?
Custer County, Idaho is in USDA Hardiness Zone 5b. The average last spring frost is June 18 and first fall frost is September 5.
When should I plant Nasturtium in Custer County, ID?
In Custer County, ID, plant Nasturtium after the last frost (around June 18) and before the first frost (around September 5). Best results when soil holds above 50°F.
What growing zone is Custer County, ID for Nasturtium?
Custer County sits in USDA Zone 5b. Nasturtium grows reliably in zones 2a through 11b, so it's a good fit here.
Can Nasturtium grow in Custer County's climate?
Yes — Nasturtium grows well in Custer County's temperate climate. Custer County averages a 79-day frost-free season, with last frost around June 18 and first frost around September 5.
Your Custer County Garden Planner — Free
A 22-page printable planner built for Custer County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.