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When to Plant Larkspur in Klamath County, OR

Klamath County, Oregon Zone 6b July

Klamath County, Oregon gardeners: here's your July plan

We've pulled the most time-sensitive tasks for Klamath County, Oregon this July and put them front and centre. Tackle them in order.

Avg. last frost June 13
Avg. first frost September 21
Soil temp (4") 82°F
Watering Critical
Pest pressure High
Daylight 14.8 hrs
  1. Start harvesting larkspur

    This is the payoff month. Bring a basket, bring a friend, and get into the beds.

August will be here before you know it — start on
  • First harvests: larkspur

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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.

Klamath County, Oregon is in USDA Zone 6b. The average last spring frost is June 13 and the first fall frost is September 21, giving you a growing season of approximately 100 days.

At an elevation of 142 feet, Klamath County receives approximately 48.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Larkspur to ensure they mature before fall.

Annual Blooms in Spring Pollinator-friendly Deer-resistant Good for cutting
Klamath County, OR (Zone 6b) Short season
100 days
Last Spring Frost June 13
100 growing days
First Fall Frost September 21

Klamath County Soil Profile

Soil Type

Silt Loam

Soil pH

5.5-6.3

Drainage

Well Drained

Larkspur Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 30 🌸 Bloom: Aug 8 – Oct 3
Recommended (50%) ✗ May not fit
Transplant: Jun 13 🌸 Bloom: Aug 22 – Oct 17
Safe Start (90%) ✗ May not fit
Transplant: Jun 26 🌸 Bloom: Sep 4 – Oct 30

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 Klamath County

How your county's soil matches Larkspur's growing requirements.

Soil pH

Your soil pH (5.5–6.3) is more acidic than Larkspur prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

The silt loam soil in Klamath County is excellent for Larkspur — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Drainage is adequate for Larkspur.

Organic Matter

Organic matter is excellent (5.1%) — Larkspur will thrive.

How to Plant Larkspur

0.1"
Planting Depth
8"
Between Plants
12"
Between Rows

Larkspur Water Budget

Plant needs
0.5″/week
Rainfall provides
2.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

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 7.4" 0" ❄️ Dormant
Feb 5.2" 0" ❄️ Dormant
Mar 4.8" 0" ❄️ Dormant
Apr 3.3" 0" ❄️ Dormant
May 3" 0" ❄️ Dormant
Jun 2.2" 1.8" 0.4" 💧 Light watering
Jul 2.2" 0.9" 1.3" 🚿 Regular watering
Aug 2.2" 0.8" 1.4" 🚿 Regular watering
Sep 2.2" 2.1" 0.1" 💧 Light watering
Oct 4.8" 0" ❄️ Dormant
Nov 7.7" 0" ❄️ Dormant
Dec 6.9" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Sep in Klamath 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 needs ~919 GDD — county provides 1,225 GDD Excellent fit

Larkspur Planting Timeline — Klamath County, OR

Larkspur Planting Calendar

Activity When Date Range
Direct Sow May 16 May 16 – Jun 6
Bloom July 25 Jul 25 – Sep 19

Plant 0.1" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April
May Direct Sow
June Direct Sow
July Bloom
August Bloom
September Bloom
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 6b

📆 Growing Season

100 days in Klamath County

Growing Tips for Larkspur in Klamath County

Direct sow Larkspur outdoors after June 13 in Klamath County when soil has warmed and frost danger has passed.

Your 100.0-day growing season in Klamath County is tight for Larkspur (60.0-90.0 days to maturity). Start indoors and choose early-maturing varieties.

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 →

Frequently Asked Questions

When should I plant Larkspur in Klamath County, OR?

Klamath County is in Zone 6b with an average last frost of June 13. Plan your Larkspur planting based on this frost date — see the calendar above for exact timing.

What planting zone is Klamath County, OR?

Klamath County, Oregon is in USDA Hardiness Zone 6b. The average last spring frost is June 13 and first fall frost is September 21.

🌱

Your Klamath County Garden Planner — Free

A 22-page printable planner built for Klamath County (Zone 6b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Klamath County, OR. Local conditions may vary. Last updated: July 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.