When to plant Foxglove in Custer County, ID
Plant Foxglove in Custer County, between July 2 and July 23 — the only viable window. Zone 5b's short season (79 frost-free days) rules out a fall crop.
When to Plant Foxglove in Custer County, ID
July in the garden — Custer County, Idaho
Your garden in Custer County, Idaho is working on a schedule, even when you're not. Here's where you should be this July.
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Transplant foxglove outside
Pinch off the lowest leaves on each seedling before you plant — it reduces water loss while the roots catch up.
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Outdoor sowing time: foxglove
Mark the row. Birds and stray feet both have opinions about unmarked beds.
A few tasks this July that'll pay off in August
- Starting indoors: foxglove
- First harvests: foxglove
Foxglove (Digitalis purpurea) is a stately cottage garden classic, sending up dramatic 3–5 foot spires of tubular flowers — spotted purple, pink, white, or cream — in late spring and early summer. Technically biennial (flowering in its second year), foxglove perpetuates itself so freely from self-sown seed that established plantings appear to be permanent perennials. A key source plant for the heart medication digitalis, all parts are highly toxic if ingested. Bumblebees are the primary pollinators, crawling deep into each bell-shaped flower. Partial shade and cool, moist woodland-edge conditions suit foxglove best; it resents heat and drought.
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 Foxglove to ensure they mature before fall.
Custer County Soil Profile
Soil Type
Loam
Soil pH
6.3-8
Drainage
Well Drained
Foxglove 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 Foxglove's growing requirements.
Soil pH
Your soil pH (6.3–8.0) is more alkaline than Foxglove prefers (5.5–6.5). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Custer County is excellent for Foxglove — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.3%). Annual compost additions will help Foxglove.
How to Plant Foxglove
Foxglove Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Foxglove
Foxglove needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Foxglove 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 | 4.3" | 1.5" | 2.8" | 🚿 Regular watering |
| Jul | 4.3" | 2" | 2.3" | 🚿 Regular watering |
| Aug | 4.3" | 2.1" | 2.2" | 🚿 Regular watering |
| Sep | 4.3" | 1.7" | 2.6" | 🚿 Regular 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.
Foxglove 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.
Foxglove Planting Timeline — Custer County, ID
Foxglove Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 16 | Apr 16 – Apr 30 |
| Transplant Outdoors | July 2 | Jul 2 – Jul 16 |
| Direct Sow | July 2 | Jul 2 – Jul 23 |
| Bloom | August 27 | Aug 27 – Oct 8 |
Plant 0.1" deep · 18" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| May | — |
| June | — |
| July | Transplant Outdoors Direct Sow |
| August | Bloom |
| September | Bloom |
| October | Bloom |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
1"/week · Natural rainfall sufficient
📅 Days to Maturity
80–120 days
🧪 Soil pH
Needs 5.5–6.5 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 5b
📆 Growing Season
79 days in Custer County
Growing Tips for Foxglove in Custer County
Direct sow Foxglove outdoors after June 18 in Custer County when soil has warmed and frost danger has passed.
Your 79.0-day growing season in Custer County is tight for Foxglove (80.0-120.0 days to maturity). Start indoors and choose early-maturing varieties.
Custer County receives only 21" of rain annually. Foxglove needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Sow seeds indoors 8–10 weeks before last frost or direct-sow outdoors in late spring/early summer for next-year bloom (biennial cycle). Surface-sow — seeds need light to germinate. Transplant after last frost into cool, moist, well-amended soil. Morning sun with afternoon shade is ideal; full shade reduces bloom but is tolerated. Keep consistently moist. First-year plants form a basal rosette only; second-year plants produce flower spikes. After bloom, cut the main spike before seed scatters to prevent excessive spreading, or leave some spikes to self-seed for naturalizing. Perennial species (D. grandiflora, D. x mertonensis) maintain clumps without requiring self-seeding. Wear gloves when handling — all plant parts toxic.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Foxglove in Other Locations
Frequently Asked Questions
When should I plant Foxglove in Custer County, ID?
Custer County is in Zone 5b with an average last frost of June 18. Plan your Foxglove 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 Foxglove in Custer County, ID?
In Custer County, ID, plant Foxglove 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 Foxglove?
Custer County sits in USDA Zone 5b. Foxglove grows reliably in zones 3a through 9a, so it's a good fit here.
Can Foxglove grow in Custer County's climate?
Yes — Foxglove 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.