When to plant Irises in Dillingham Census Area County,
Dillingham Census Area County's short 128-day growing season means one Irises planting between May 15 and May 29. No fall crop in Zone 4b.
When to Plant Irises in Dillingham Census Area, AK
Your June planting checklist for Dillingham Census Area, Alaska
Each item below is timed to Dillingham Census Area, Alaska's frost dates and soil temperatures. Skip nothing, stress about nothing.
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.
Dillingham Census Area, Alaska is in USDA Zone 4b. The average last spring frost is May 1 and the first fall frost is September 6, giving you a growing season of approximately 128 days.
At an elevation of 410 feet, Dillingham Census Area receives approximately 54 inches of rainfall annually with predominantly silt loam soil. Summer highs average 60°F, so choose short-season varieties of Irises to ensure they mature before fall. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Irises root diseases.
Dillingham Census Area Soil Profile
Soil Type
Silt Loam
Soil pH
5-6.2
Drainage
Well Drained
Irises 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 Dillingham Census Area
How your county's soil matches Irises's growing requirements.
Soil pH
Your soil pH (5.0–6.2) is more acidic than Irises prefers (6.8–7.0). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Dillingham Census Area is excellent for Irises — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Irises prefers dry conditions but your soil drains poorly. Use raised beds or mounded rows to prevent root rot.
Organic Matter
Organic matter is excellent (6.6%) — Irises will thrive.
How to Plant Irises
Irises Water Budget
Monthly Watering Guide for Irises
Irises 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 | Irises Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 2.6" | 0" | ❄️ Dormant |
| Feb | — | 2.4" | 0" | ❄️ Dormant |
| Mar | — | 2.2" | 0" | ❄️ Dormant |
| Apr | — | 1.8" | 0" | ❄️ Dormant |
| May | 2.2" | 2.3" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 3.5" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 7.3" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 8.4" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 9.5" | 0" | ✅ Rainfall sufficient |
| Oct | — | 6.5" | 0" | ❄️ Dormant |
| Nov | — | 4.2" | 0" | ❄️ Dormant |
| Dec | — | 3.3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Dillingham Census Area). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Irises 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.
Irises Planting Timeline — Dillingham Census Area, AK
Irises Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | May 15 | May 15 – May 29 |
| Bloom | July 10 | Jul 10 – Aug 14 |
Plant 0.5" deep · 18" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Transplant Outdoors |
| June | — |
| July | Bloom |
| August | Bloom |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Natural rainfall sufficient
📅 Days to Maturity
60–100 days
🧪 Soil pH
Needs 6.8–7 · Your soil: too_acidic
🗺️ USDA Zone
Zone 4b
📆 Growing Season
128 days in Dillingham Census Area
Growing Tips for Dillingham Census Area
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 Dillingham Census Area, AK?
Dillingham Census Area is in Zone 4b with an average last frost of May 1. Plan your Irises planting based on this frost date — see the calendar above for exact timing.
What planting zone is Dillingham Census Area, AK?
Dillingham Census Area, Alaska is in USDA Hardiness Zone 4b. The average last spring frost is May 1 and first fall frost is September 6.
When should I plant Irises in Dillingham Census Area, ?
In Dillingham Census Area, , plant Irises after the last frost (around May 1) and before the first frost (around September 6). Best results when soil holds above 50°F.
What growing zone is Dillingham Census Area, for Irises?
Dillingham Census Area sits in USDA Zone 4b. Irises grows reliably in zones 3a through 9b, so it's a good fit here.
Can Irises grow in Dillingham Census Area's climate?
Yes — Irises grows well in Dillingham Census Area's temperate climate. Dillingham Census Area averages a 128-day frost-free season, with last frost around May 1 and first frost around September 6.
Your Dillingham Census Area Garden Planner — Free
A 22-page printable planner built for Dillingham Census Area (Zone 4b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.