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When to plant Ranunculus in Phillipsville, CA

For Phillipsville, gardeners: plant Ranunculus mid-spring through late spring once soil reads 50°F. A second sowing from October 17 to October 31 extends the harvest into fall.

When to Plant Ranunculus in Phillipsville, CA

Humboldt County, California Zone 9b August

Your August game plan for Humboldt County, California

If you only do a handful of things in the garden this August, make it these. They're sequenced around your zone's frost timing.

Avg. last frost February 27
Avg. first frost November 28
Soil temp (4") 93°F
Watering Critical
Pest pressure High
Daylight 13.6 hrs

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Persian ranunculus (Ranunculus asiaticus) produces multi-petaled blooms that rival roses in intricacy and lushness, in a warm palette of reds, oranges, yellows, pinks, and whites. A cornerstone of the specialty cut flower industry, ranunculus produces long, strong stems ideal for bouquets and arrangements. As a cool-season corm, it performs best in the mild shoulder seasons — planted in fall in warm-winter zones, or in early spring where summers arrive quickly. The 'Elegance', 'Amandine', and 'Tecolote' strains are favorites for both home gardens and commercial growers.

Phillipsville, California is in USDA Zone 9b. The average last spring frost is February 27 and the first fall frost is November 28, giving you a growing season of approximately 274 days.

At an elevation of 148 feet, Humboldt County receives approximately 22.1 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 87°F, providing good warmth for Ranunculus during the growing season. Sandy soil warms quickly in spring — great for early planting — but Ranunculus will need more frequent watering and organic matter to retain nutrients.

Bulb Blooms in Spring Pollinator-friendly Good for cutting
Phillipsville, CA (Zone 9b) Year-round
274 days
Last Spring Frost February 27
274 growing days
First Fall Frost November 28

Phillipsville Soil Profile

Soil Type

Sandy Loam

Soil pH

6.2-6.8

Drainage

Well Drained

Ranunculus Planting Risk Windows

Early Start (70% safe) ✓ Fits season (248 days to spare)
Transplant: Feb 13 🌸 Bloom: Feb 20 – Mar 20
Recommended (50%) ✓ Fits season (239 days to spare)
Transplant: Feb 27 🌸 Bloom: Mar 6 – Apr 3
Safe Start (90%) ✓ Fits season (225 days to spare)
Transplant: Apr 2 🌸 Bloom: Apr 9 – May 7

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 Phillipsville

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

Soil pH

Your soil pH (6.2–6.8) overlaps with Ranunculus's range (6.0–6.5), though not a perfect match.

Soil Texture

Sandy soil in Humboldt County warms quickly in spring but drains fast. Ranunculus will need more frequent watering and regular compost additions to retain nutrients.

Organic Matter

Organic matter is moderate (2.3%). Annual compost additions will help Ranunculus.

How to Plant Ranunculus

2"
Planting Depth
6"
Between Plants
8"
Between Rows

Fall planting: Sow 6 weeks before your first frost date for a fall harvest.

Ranunculus Water Budget

Plant needs
1.0″/week
Rainfall provides
0.3″/week
You supply
0.7″/week
Watering frequency 1-2 times/week
Season total 1,621 gal / 100 sq ft

Monthly Watering Guide for Ranunculus

Ranunculus needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Ranunculus Needs Rainfall You Supplement Action
Jan 4.8" 0" ❄️ Dormant
Feb 4.3" 5" 0" ✅ Rainfall sufficient
Mar 4.3" 3.3" 1" 💧 Light watering
Apr 4.3" 1.7" 2.6" 🚿 Regular watering
May 4.3" 0.5" 3.8" 🚿 Regular watering
Jun 4.3" 0.1" 4.2" 🚿 Regular watering
Jul 4.3" 0" 4.3" 🚿 Regular watering
Aug 4.3" 0" 4.3" 🚿 Regular watering
Sep 4.3" 0.3" 4" 🚿 Regular watering
Oct 4.3" 0.8" 3.5" 🚿 Regular watering
Nov 4.3" 1.9" 2.4" 🚿 Regular watering
Dec 3.7" 0" ❄️ Dormant

Water needs are for active growing months only (Feb–Nov in Humboldt County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Ranunculus 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.

Ranunculus needs ~1,601 GDD — county provides 4,193 GDD Excellent fit

Ranunculus Planting Timeline — Phillipsville, CA

Ranunculus Planting Calendar

Activity When Date Range
Bloom October 24 Oct 24 – Nov 21
Fall Sowing October 17 Oct 17 – Oct 31

Plant 2" deep · 6" apart · Rows 8" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April
May
June
July
August
September
October Fall Sowing Bloom
November Bloom
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

90–120 days

🧪 Soil pH

Needs 6–6.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 9b

📆 Growing Season

274 days in Humboldt County

Growing Tips for Ranunculus in Phillipsville

Direct sow Ranunculus outdoors after February 27 in Humboldt County when soil has warmed and frost danger has passed.

Sandy soil in Humboldt County dries quickly — mulch Ranunculus with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

Humboldt County receives only 22" of rain annually. Ranunculus needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Pre-soak corms (which look like small octopus tentacles) in cool water for 2–4 hours before planting; do not over-soak. Plant with tentacles pointing downward, 1–2 inches deep and 6 inches apart. Ranunculus demand excellent drainage — they rot in soggy soil. In fall-planting zones (7+), plant October–November and allow to root through mild winter; blooms arrive in March–May. In zones 6, start corms indoors in late winter and transplant out after last frost for a late-spring bloom. Keep soil consistently moist but never waterlogged during growth. After foliage yellows (post-bloom), stop watering, let corms dry, lift them, and store in a cool dry place until replanting. In zones 8b–10b, corms can often be left in ground year-round.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

When should I plant Ranunculus in Phillipsville, CA?

In Phillipsville, CA, plant Ranunculus after the last frost (around February 27) and before the first frost (around November 28). Best results when soil holds above 50°F.

What growing zone is Phillipsville, CA for Ranunculus?

Phillipsville sits in USDA Zone 9b. Ranunculus grows reliably in zones 6a through 10b, so it's a good fit here.

Can Ranunculus grow in Phillipsville's climate?

Yes — Ranunculus grows well in Phillipsville's temperate climate. Phillipsville averages a 275-day frost-free season, with last frost around February 27 and first frost around November 28.

🌱

Your Humboldt County Garden Planner — Free

A 22-page printable planner built for Humboldt County (Zone 9b). 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 Humboldt County, CA. Local conditions may vary. Last updated: August 2026.