When to Plant Larkspur in Harmon County, OK
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.
Harmon County, Oklahoma is in USDA Zone 7b. The average last spring frost is March 31 and the first fall frost is November 5, giving you a growing season of approximately 219 days.
At an elevation of 993 feet, Harmon County receives approximately 34.4 inches of rainfall annually with predominantly loam soil. Summer highs average 91°F, providing good warmth for Larkspur during the growing season.
Harmon County Soil Profile
Soil Type
Loam
Soil pH
6.5-7.5
Drainage
Well Drained
Monthly Watering Guide for Larkspur
Larkspur needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Larkspur Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 0.9" | 0" | ❄️ Dormant |
| Feb | — | 1.2" | 0" | ❄️ Dormant |
| Mar | 4.3" | 2.3" | 2" | 💧 Light watering |
| Apr | 4.3" | 3.7" | 0.6" | 💧 Light watering |
| May | 4.3" | 5.1" | 0" | ✅ Rainfall sufficient |
| Jun | 4.3" | 5" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 4.1" | 0.2" | 💧 Light watering |
| Aug | 4.3" | 4.8" | 0" | ✅ Rainfall sufficient |
| Sep | 4.3" | 3" | 1.3" | 💧 Light watering |
| Oct | 4.3" | 2" | 2.3" | 🚿 Regular watering |
| Nov | 4.3" | 1.3" | 3" | 🚿 Regular watering |
| Dec | — | 1" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Mar–Nov in Harmon County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Larkspur Planting Timeline — Harmon County, OK
Larkspur Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | March 3 | Mar 3 – Mar 24 |
| Bloom | May 12 | May 12 – Aug 4 |
| Fall Sowing | August 27 | Aug 27 – Sep 10 |
Plant 0.1" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Direct Sow |
| April | — |
| May | Bloom |
| June | Bloom |
| July | Bloom |
| August | Fall Sowing Bloom |
| September | Fall Sowing |
| 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 7b
📆 Growing Season
219 days in Harmon County
Growing Tips for Harmon 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 Harmon County, OK?
Harmon County is in Zone 7b with an average last frost of March 31. Plan your Larkspur planting based on this frost date — see the calendar above for exact timing.
What planting zone is Harmon County, OK?
Harmon County, Oklahoma is in USDA Hardiness Zone 7b. The average last spring frost is March 31 and first fall frost is November 5.
Your Harmon County Garden Planner — Free
A 22-page printable planner built for Harmon County (Zone 7b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.