When to plant Larkspur in Larimer County, CO
In Larimer County, plant Larkspur in spring between April 4 and April 25, once soil temps hold above 50°F. Larimer County's last frost averages May 2, so time plantings around the expected last-frost window for best survival. For a fall crop, sow between and — roughly 60–90 days before the first frost on October 6.
When to Plant Larkspur in Larimer County, CO
Larkspur (Consolida ajacis) is a cool-season annual that produces tall, delicate spires of blue, purple, pink, and white flowers reminiscent of its perennial cousin, delphinium. Direct-sown into cold soil or fall-sown in mild-winter climates, it blooms in spring before going to seed as summer heat arrives. An excellent cut flower and cottage-garden staple.
Larimer County, Colorado is in USDA Zone 5b. The average last spring frost is May 2 and the first fall frost is October 6, giving you a growing season of approximately 157 days.
At an elevation of 7,108 feet, Larimer County receives approximately 23.4 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Larkspur to ensure they mature before fall.
Larimer County Soil Profile
Soil Type
Loam
Soil pH
6.0-7.0
Drainage
Well Drained
Larkspur Planting Timeline — Larimer County, CO
Larkspur Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | April 4 | Apr 4 – Apr 25 |
| Bloom | June 13 | Jun 13 – Aug 8 |
Plant 0.1" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Direct Sow |
| May | — |
| June | Bloom |
| July | Bloom |
| August | Bloom |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
Low — drought tolerant
📅 Days to Maturity
60–90 days
🧪 Soil pH
Needs 6–7 · Your soil: N/A
🗺️ USDA Zone
Zone 5b
📆 Growing Season
157 days in Larimer County
Growing Tips for Larimer County
Larkspur does not transplant well — direct-sow only. In cold climates (zones 2–6), sow directly in early spring as soon as soil can be worked, 4–6 weeks before last frost; cold soil improves germination. In zones 7–10, fall-sow 8–10 weeks before first frost for spring bloom. Press seeds lightly into soil; they need darkness to germinate — cover with 1/8–1/4 inch of soil. Thin to 6–12 inches to prevent powdery mildew. Allow seed pods to mature and self-sow for naturalized colonies. All parts are toxic if ingested.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Larkspur in Other Locations
Frequently Asked Questions
When should I plant Larkspur in Larimer County, CO?
Larimer County is in Zone 5b with an average last frost of May 2. Plan your Larkspur planting based on this frost date — see the calendar above for exact timing.
What planting zone is Larimer County, CO?
Larimer County, Colorado is in USDA Hardiness Zone 5b. The average last spring frost is May 2 and first fall frost is October 6.
When should I plant Larkspur in Larimer County, CO?
In Larimer County, CO, plant Larkspur after the last frost (around May 2) and before the first frost (around October 6). Best results when soil holds above 50°F.
What growing zone is Larimer County, CO for Larkspur?
Larimer County sits in USDA Zone 5b. Larkspur grows reliably in zones 2a through 10b, so it's a good fit here.
Can Larkspur grow in Larimer County's climate?
Yes — Larkspur grows well in Larimer County's temperate climate. Larimer County averages a 157-day frost-free season, with last frost around May 2 and first frost around October 6.
Your Larimer County Garden Planner — Free
A 22-page printable planner built for Larimer County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.