When to plant Irises in Clearwater County, MN
In Clearwater County, Irises is a single-season spring crop — there's no second fall window. Plant May 29–June 12 for an 100-day harvest, finishing well before the September 28 first frost.
When to Plant Irises in Clearwater County, MN
June in the garden — Clearwater County, Minnesota
Each item below is timed to Clearwater County, Minnesota's frost dates and soil temperatures. Skip nothing, stress about nothing.
July prep starts now
- First harvests: irises
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.
Clearwater County, Minnesota is in USDA Zone 3b. The average last spring frost is May 15 and the first fall frost is September 28, giving you a growing season of approximately 136 days.
At an elevation of 1,074 feet, Clearwater County receives approximately 33.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Irises to ensure they mature before fall.
Clearwater County Soil Profile
Soil Type
Silt Loam
Soil pH
6.2-7.2
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 Clearwater County
How your county's soil matches Irises's growing requirements.
Soil pH
Your soil pH (6.2–7.2) is more acidic than Irises prefers (6.8–7.0). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Clearwater County is excellent for Irises — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Irises.
Organic Matter
Organic matter is excellent (4.6%) — Irises will thrive.
How to Plant Irises
Succession Planting Irises
Sow every 6.9 weeks. Last sowing by Jun 20 to harvest before frost.
Irises Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
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 | — | 1.5" | 0" | ❄️ Dormant |
| Feb | — | 1.4" | 0" | ❄️ Dormant |
| Mar | — | 2.1" | 0" | ❄️ Dormant |
| Apr | — | 2.8" | 0" | ❄️ Dormant |
| May | 2.2" | 4.2" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 3.8" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 3.6" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 3.8" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 3.3" | 0" | ✅ Rainfall sufficient |
| Oct | — | 2.5" | 0" | ❄️ Dormant |
| Nov | — | 2.6" | 0" | ❄️ Dormant |
| Dec | — | 2.1" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Clearwater County). 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 — Clearwater County, MN
Irises Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | May 29 | May 29 – Jun 12 |
| Bloom | July 24 | Jul 24 – Aug 21 |
Plant 0.5" deep · 18" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Transplant Outdoors |
| June | Transplant Outdoors |
| 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 3b
📆 Growing Season
136 days in Clearwater County
Growing Tips for Irises in Clearwater County
Direct sow Irises outdoors after May 15 in Clearwater County when soil has warmed and frost danger has passed.
General growing tips
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 Clearwater County, MN?
Clearwater County is in Zone 3b with an average last frost of May 15. Plan your Irises planting based on this frost date — see the calendar above for exact timing.
What planting zone is Clearwater County, MN?
Clearwater County, Minnesota is in USDA Hardiness Zone 3b. The average last spring frost is May 15 and first fall frost is September 28.
When should I plant Irises in Clearwater County, MN?
In Clearwater County, MN, plant Irises after the last frost (around May 15) and before the first frost (around September 28). Best results when soil holds above 50°F.
What growing zone is Clearwater County, MN for Irises?
Clearwater County sits in USDA Zone 3b. Irises grows reliably in zones 3a through 9b, so it's a good fit here.
Can Irises grow in Clearwater County's climate?
Yes — Irises grows well in Clearwater County's temperate climate. Clearwater County averages a 136-day frost-free season, with last frost around May 15 and first frost around September 28.
Your Clearwater County Garden Planner — Free
A 22-page printable planner built for Clearwater County (Zone 3b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.