When to plant Larkspur in Franklin County, IL
Franklin County sits in USDA Zone 7a. Plant Larkspur between March 13 (after last frost on April 10) and April 3. A second sowing from August 11 to August 25 extends the harvest into fall.
When to Plant Larkspur in Franklin County, IL
June in Franklin County, Illinois — your action list
If you only do a handful of things in the garden this June, make it these. They're sequenced around your zone's frost timing.
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Harvest larkspur as they ripen
Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.
A few tasks this June that'll pay off in July
- First harvests: larkspur
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.
Franklin County, Illinois is in USDA Zone 7a. The average last spring frost is April 10 and the first fall frost is October 20, giving you a growing season of approximately 193 days.
At an elevation of 747 feet, Franklin County receives approximately 37.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 89°F, providing good warmth for Larkspur during the growing season.
Franklin County Soil Profile
Soil Type
Silt Loam
Soil pH
5.9-7.1
Drainage
Well Drained
Larkspur 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 Franklin County
How your county's soil matches Larkspur's growing requirements.
Soil pH
Your soil pH (5.9–7.1) overlaps with Larkspur's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Franklin County is excellent for Larkspur — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.3%) — Larkspur will thrive.
How to Plant Larkspur
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Succession Planting Larkspur
Sow every 6.9 weeks. Last sowing by Jul 22 to harvest before frost.
For a dedicated fall crop, sow by Aug 11.
Larkspur Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Larkspur
Larkspur 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 | Larkspur Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.4" | 0" | ❄️ Dormant |
| Feb | — | 1.7" | 0" | ❄️ Dormant |
| Mar | — | 2.7" | 0" | ❄️ Dormant |
| Apr | 2.2" | 3.9" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 4.4" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 4.7" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 3.6" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 4.1" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 2.9" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 3.1" | 0" | ✅ Rainfall sufficient |
| Nov | — | 2.6" | 0" | ❄️ Dormant |
| Dec | — | 2.3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Franklin County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Larkspur 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.
Larkspur Planting Timeline — Franklin County, IL
Larkspur Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | March 13 | Mar 13 – Apr 3 |
| Bloom | May 22 | May 22 – Jul 31 |
| Fall Sowing | August 11 | Aug 11 – Aug 25 |
Plant 0.1" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Direct Sow |
| April | Direct Sow |
| May | Bloom |
| June | Bloom |
| July | Bloom |
| August | Fall Sowing |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Natural rainfall sufficient
📅 Days to Maturity
60–90 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 7a
📆 Growing Season
193 days in Franklin County
Growing Tips for Larkspur in Franklin County
Direct sow Larkspur outdoors after April 10 in Franklin County when soil has warmed and frost danger has passed.
General growing tips
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 Franklin County, IL?
Franklin County is in Zone 7a with an average last frost of April 10. Plan your Larkspur planting based on this frost date — see the calendar above for exact timing.
What planting zone is Franklin County, IL?
Franklin County, Illinois is in USDA Hardiness Zone 7a. The average last spring frost is April 10 and first fall frost is October 20.
When should I plant Larkspur in Franklin County, IL?
In Franklin County, IL, plant Larkspur after the last frost (around April 10) and before the first frost (around October 20). Best results when soil holds above 50°F.
What growing zone is Franklin County, IL for Larkspur?
Franklin County sits in USDA Zone 7a. Larkspur grows reliably in zones 2a through 10b, so it's a good fit here.
Can Larkspur grow in Franklin County's climate?
Yes — Larkspur grows well in Franklin County's temperate climate. Franklin County averages a 193-day frost-free season, with last frost around April 10 and first frost around October 20.
Your Franklin County Garden Planner — Free
A 22-page printable planner built for Franklin County (Zone 7a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.