When to plant Larkspur in Barnstable County, MA
Barnstable County's climate puts the Larkspur spring window between March 21 and April 11. most warm-season crops establish quickly once soil holds above 60°F. A second sowing from August 15 to August 29 extends the harvest into fall.
When to Plant Larkspur in Barnstable County, MA
August to-do list for Barnstable County, Massachusetts
Each item below is timed to Barnstable County, Massachusetts's frost dates and soil temperatures. Skip nothing, stress about nothing.
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Harvest larkspur as they ripen
Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.
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Direct-sow larkspur for cool weather
Fall crops get sweeter with a light frost. Don't be afraid of cool nights.
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.
Barnstable County, Massachusetts is in USDA Zone 7a. The average last spring frost is April 18 and the first fall frost is October 24, giving you a growing season of approximately 189 days.
At an elevation of 518 feet, Barnstable County receives approximately 45.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 91°F, providing good warmth for Larkspur during the growing season.
Barnstable County Soil Profile
Soil Type
Silt Loam
Soil pH
5-6.4
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 Barnstable County
How your county's soil matches Larkspur's growing requirements.
Soil pH
Your soil pH (5.0–6.4) is more acidic than Larkspur prefers (6.0–7.0). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Barnstable County is excellent for Larkspur — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (3.0%). Annual compost additions will help Larkspur.
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 26 to harvest before frost.
For a dedicated fall crop, sow by Aug 15.
Larkspur Water Budget
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 | — | 3.2" | 0" | ❄️ Dormant |
| Feb | — | 3.1" | 0" | ❄️ Dormant |
| Mar | — | 4.2" | 0" | ❄️ Dormant |
| Apr | 2.2" | 3.6" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 4.7" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 4.7" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 4.9" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 4.2" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 3.4" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 3.3" | 0" | ✅ Rainfall sufficient |
| Nov | — | 3.2" | 0" | ❄️ Dormant |
| Dec | — | 3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Barnstable 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 — Barnstable County, MA
Larkspur Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | March 21 | Mar 21 – Apr 11 |
| Bloom | May 30 | May 30 – Aug 8 |
| Fall Sowing | August 15 | Aug 15 – Aug 29 |
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 Bloom |
| 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: too_acidic
🗺️ USDA Zone
Zone 7a
📆 Growing Season
189 days in Barnstable County
Growing Tips for Larkspur in Barnstable County
Direct sow Larkspur outdoors after April 18 in Barnstable 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 Barnstable County, MA?
Barnstable County is in Zone 7a with an average last frost of April 18. Plan your Larkspur planting based on this frost date — see the calendar above for exact timing.
What planting zone is Barnstable County, MA?
Barnstable County, Massachusetts is in USDA Hardiness Zone 7a. The average last spring frost is April 18 and first fall frost is October 24.
When should I plant Larkspur in Barnstable County, MA?
In Barnstable County, MA, plant Larkspur after the last frost (around April 18) and before the first frost (around October 24). Best results when soil holds above 50°F.
What growing zone is Barnstable County, MA for Larkspur?
Barnstable 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 Barnstable County's climate?
Yes — Larkspur grows well in Barnstable County's temperate climate. Barnstable County averages a 189-day frost-free season, with last frost around April 18 and first frost around October 24.
Your Barnstable County Garden Planner — Free
A 22-page printable planner built for Barnstable 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.