When to plant Alliums in Clark County, ID
In Zone 5b (Clark County), direct-sow Alliums between mid-spring and late spring for spring, after the June 7 last-frost mark. A second sowing from July 30 to August 13 extends the harvest into fall.
When to Plant Alliums in Clark County, ID
Ornamental alliums (Allium spp.) bridge the gap between spring and summer with their striking globe-shaped flower heads in shades of purple, violet, white, and pink. Blooming after tulips have faded, they extend the spring display well into early summer. 'Gladiator', 'Globemaster', and 'Purple Sensation' produce softball-sized heads on 18–36 inch stems, while smaller species create charming accents at border fronts. Deer and rodents shun them completely due to the characteristic onion scent. Dried seed heads provide architectural interest into fall.
Clark County, Idaho is in USDA Zone 5b. The average last spring frost is June 7 and the first fall frost is September 10, giving you a growing season of approximately 95 days.
At an elevation of 7,493 feet, Clark County receives approximately 21.9 inches of rainfall annually with predominantly loam soil. Summer highs average 82°F, so choose short-season varieties of Alliums to ensure they mature before fall.
Clark County Soil Profile
Soil Type
Loam
Soil pH
6.8-7.8
Drainage
Well Drained
Monthly Watering Guide for Alliums
Alliums needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Alliums Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.7" | 0" | ❄️ Dormant |
| Feb | — | 1.4" | 0" | ❄️ Dormant |
| Mar | — | 1.8" | 0" | ❄️ Dormant |
| Apr | — | 2.5" | 0" | ❄️ Dormant |
| May | — | 2.5" | 0" | ❄️ Dormant |
| Jun | 4.3" | 1.5" | 2.8" | 🚿 Regular watering |
| Jul | 4.3" | 1.7" | 2.6" | 🚿 Regular watering |
| Aug | 4.3" | 2.2" | 2.1" | 💧 Light watering |
| Sep | 4.3" | 1.7" | 2.6" | 🚿 Regular watering |
| Oct | — | 1.8" | 0" | ❄️ Dormant |
| Nov | — | 1.6" | 0" | ❄️ Dormant |
| Dec | — | 1.3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Jun–Sep in Clark County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Alliums Planting Timeline — Clark County, ID
Alliums Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Bloom | September 3 | Sep 3 – Sep 24 |
| Fall Sowing | July 30 | Jul 30 – Aug 13 |
Plant 5" deep · 7" apart · Rows 8" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | — |
| June | — |
| July | Fall Sowing |
| August | Fall Sowing |
| September | Bloom |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
Low — drought tolerant
📅 Days to Maturity
28–42 days
🧪 Soil pH
Needs 5.5–7.5 · Your soil: N/A
🗺️ USDA Zone
Zone 5b
📆 Growing Season
95 days in Clark County
Growing Tips for Clark County
Plant bulbs in fall, 3–4 times as deep as the bulb diameter (typically 4–6 inches for large types, 3 inches for small species). Space 6–8 inches apart for standard cultivars. Foliage often looks untidy as it dies back before bloom — plant around perennials that will conceal the yellowing leaves. Excellent drainage is essential; alliums rot in wet soils. Leave bulbs in place for naturalization; divide every 3–4 years when clusters become congested. Deadhead spent globes or leave for ornamental seedheads and self-sowing.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Alliums in Other Locations
Frequently Asked Questions
When should I plant Alliums in Clark County, ID?
Clark County is in Zone 5b with an average last frost of June 7. Plan your Alliums planting based on this frost date — see the calendar above for exact timing.
What planting zone is Clark County, ID?
Clark County, Idaho is in USDA Hardiness Zone 5b. The average last spring frost is June 7 and first fall frost is September 10.
When should I plant Alliums in Clark County, ID?
In Clark County, ID, plant Alliums after the last frost (around June 7) and before the first frost (around September 10). Best results when soil holds above 50°F.
What growing zone is Clark County, ID for Alliums?
Clark County sits in USDA Zone 5b. Alliums grows reliably in zones 3a through 9b, so it's a good fit here.
Can Alliums grow in Clark County's climate?
Yes — Alliums grows well in Clark County's temperate climate. Clark County averages a 95-day frost-free season, with last frost around June 7 and first frost around September 10.
Your Clark County Garden Planner — Free
A 22-page printable planner built for Clark 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.