When to plant Irises in Garfield County, CO
Plant Irises in Garfield County during the brief June 1–June 15 window. With 119 frost-free days, fall plantings can't mature before September 21.
When to Plant Irises in Garfield County, CO
Garfield County, Colorado gardeners: here's your June plan
A quick June briefing for Garfield County, Colorado gardeners — what's urgent, what's next, and what can wait.
-
Get irises in the ground
Pick a cloudy afternoon or evening to plant. Less transplant shock, and your seedlings will barely blink.
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.
Garfield County, Colorado is in USDA Zone 6a. The average last spring frost is May 25 and the first fall frost is September 21, giving you a growing season of approximately 119 days.
At an elevation of 7,997 feet, Garfield County receives approximately 21.3 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Irises to ensure they mature before fall.
Garfield County Soil Profile
Soil Type
Loam
Soil pH
6.5-7.9
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 Garfield County
How your county's soil matches Irises's growing requirements.
Soil pH
Your soil pH (6.5–7.9) is more alkaline than Irises prefers (6.8–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Garfield County is excellent for Irises — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.8%). Annual compost additions will help Irises.
How to Plant Irises
Succession Planting Irises
Sow every 6.9 weeks. Last sowing by Jun 13 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 | — | 1.3" | 0" | ❄️ Dormant |
| Mar | — | 1.6" | 0" | ❄️ Dormant |
| Apr | — | 2.5" | 0" | ❄️ Dormant |
| May | 2.2" | 2.6" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 1.4" | 0.8" | 💧 Light watering |
| Jul | 2.2" | 1.8" | 0.4" | 💧 Light watering |
| Aug | 2.2" | 2.2" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 1.8" | 0.4" | 💧 Light watering |
| Oct | — | 1.7" | 0" | ❄️ Dormant |
| Nov | — | 1.6" | 0" | ❄️ Dormant |
| Dec | — | 1.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Garfield 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 — Garfield County, CO
Irises Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | June 1 | Jun 1 – Jun 15 |
| Bloom | July 27 | Jul 27 – Aug 24 |
Plant 0.5" deep · 18" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | — |
| 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_alkaline
🗺️ USDA Zone
Zone 6a
📆 Growing Season
119 days in Garfield County
Growing Tips for Irises in Garfield County
Direct sow Irises outdoors after May 25 in Garfield County when soil has warmed and frost danger has passed.
Garfield County receives only 21" of rain annually. Irises needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
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 Garfield County, CO?
Garfield County is in Zone 6a with an average last frost of May 25. Plan your Irises planting based on this frost date — see the calendar above for exact timing.
What planting zone is Garfield County, CO?
Garfield County, Colorado is in USDA Hardiness Zone 6a. The average last spring frost is May 25 and first fall frost is September 21.
When should I plant Irises in Garfield County, CO?
In Garfield County, CO, plant Irises after the last frost (around May 25) and before the first frost (around September 21). Best results when soil holds above 50°F.
What growing zone is Garfield County, CO for Irises?
Garfield County sits in USDA Zone 6a. Irises grows reliably in zones 3a through 9b, so it's a good fit here.
Can Irises grow in Garfield County's climate?
Yes — Irises grows well in Garfield County's temperate climate. Garfield County averages a 119-day frost-free season, with last frost around May 25 and first frost around September 21.
Your Garfield County Garden Planner — Free
A 22-page printable planner built for Garfield County (Zone 6a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.