When to plant Irises in Linn County, MO
Linn County's 186-day season only supports one Irises planting per year. Sow between April 24 and May 8 for the best chance at full maturity before October 20.
When to Plant Irises in Linn County, MO
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.
Linn County, Missouri is in USDA Zone 6a. The average last spring frost is April 17 and the first fall frost is October 20, giving you a growing season of approximately 186 days.
At an elevation of 880 feet, Linn County receives approximately 32.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Irises during the growing season.
Linn County Soil Profile
Soil Type
Silt Loam
Soil pH
6.0-7.0
Drainage
Well Drained
Irises Planting Timeline — Linn County, MO
Irises Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | April 24 | Apr 24 – May 8 |
| Bloom | June 19 | Jun 19 – Jul 17 |
Plant 0.5" deep · 18" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Transplant Outdoors |
| May | Transplant Outdoors |
| June | Bloom |
| July | Bloom |
| 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 6a
📆 Growing Season
186 days in Linn County
Growing Tips for Linn 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 Linn County, MO?
Linn County is in Zone 6a with an average last frost of April 17. Plan your Irises planting based on this frost date — see the calendar above for exact timing.
What planting zone is Linn County, MO?
Linn County, Missouri is in USDA Hardiness Zone 6a. The average last spring frost is April 17 and first fall frost is October 20.
When should I plant Irises in Linn County, MO?
In Linn County, MO, plant Irises after the last frost (around April 17) and before the first frost (around October 20). Best results when soil holds above 50°F.
What growing zone is Linn County, MO for Irises?
Linn 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 Linn County's climate?
Yes — Irises grows well in Linn County's temperate climate. Linn County averages a 186-day frost-free season, with last frost around April 17 and first frost around October 20.
Your Linn County Garden Planner — Free
A 22-page printable planner built for Linn 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.