When to Plant Irises in Skagit County, WA
Bearded Iris (Iris germanica) are among the most regal flowers of the late-spring garden, producing elegantly ruffled blooms in virtually every color of the rainbow — often in spectacular bicolor combinations. Named for the fuzzy "beard" on the lower falls (petals), bearded irises grow from thick horizontal rhizomes that spread to form dense clumps over time. Individual blooms last only a few days, but a well-established clump produces successive flowers over 3–4 weeks. Many are intensely fragrant. Native iris species including blue flag iris (I. versicolor) and Virginia iris (I. virginica) are excellent choices for wet or native garden settings.
Skagit County, Washington is in USDA Zone 8b. The average last spring frost is April 3 and the first fall frost is October 28, giving you a growing season of approximately 208 days.
At an elevation of 232 feet, Skagit County receives approximately 42.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Irises during the growing season.
Skagit County Soil Profile
Soil Type
Silt Loam
Soil pH
5.6-6.6
Drainage
Well Drained
Monthly Watering Guide for Irises
Irises needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Irises Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 6.5" | 0" | ❄️ Dormant |
| Feb | — | 4.2" | 0" | ❄️ Dormant |
| Mar | — | 3.9" | 0" | ❄️ Dormant |
| Apr | 4.3" | 3" | 1.3" | 💧 Light watering |
| May | 4.3" | 2.8" | 1.5" | 💧 Light watering |
| Jun | 4.3" | 1.8" | 2.5" | 🚿 Regular watering |
| Jul | 4.3" | 0.7" | 3.6" | 🚿 Regular watering |
| Aug | 4.3" | 0.7" | 3.6" | 🚿 Regular watering |
| Sep | 4.3" | 1.5" | 2.8" | 🚿 Regular watering |
| Oct | 4.3" | 3.6" | 0.7" | 💧 Light watering |
| Nov | — | 6.9" | 0" | ❄️ Dormant |
| Dec | — | 6.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Skagit County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Irises Planting Timeline — Skagit County, WA
Irises Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | March 27 | Mar 27 – Apr 10 |
| Bloom | May 15 | May 15 – Jun 19 |
Plant 0.5" deep · 18" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Transplant Outdoors |
| April | Transplant Outdoors |
| May | Bloom |
| June | Bloom |
| July | — |
| August | — |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
Low — drought tolerant
📅 Days to Maturity
60–100 days
🧪 Soil pH
Needs 6.8–7 · Your soil: N/A
🗺️ USDA Zone
Zone 8b
📆 Growing Season
208 days in Skagit County
Growing Tips for Skagit County
Plant rhizomes in late summer to early fall (July–September) after bloom season, setting them horizontally with the top of the rhizome at or just slightly below soil surface — never deeply buried. Full sun is essential for best bloom; at least 6 hours. Well-drained soil is critical; wet rhizomes rot in winter. After bloom, remove flower stalks but leave foliage until it browns in fall. Divide every 3–5 years in late summer when clumps become congested (crowded rhizomes stop blooming). Iris borer is the primary pest — remove and destroy affected fans. Year 2+ after division delivers the most bloom; freshly divided rhizomes may have limited or no bloom in their first season.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Irises in Other Locations
Frequently Asked Questions
When should I plant Irises in Skagit County, WA?
Skagit County is in Zone 8b with an average last frost of April 3. Plan your Irises planting based on this frost date — see the calendar above for exact timing.
What planting zone is Skagit County, WA?
Skagit County, Washington is in USDA Hardiness Zone 8b. The average last spring frost is April 3 and first fall frost is October 28.
Your Skagit County Garden Planner — Free
A 22-page printable planner built for Skagit County (Zone 8b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.