When to plant Leeks in Angwin, CA
Angwin sits in USDA Zone 9b. Plant Leeks between February 5 (after last frost on February 26) and February 26. A second sowing from October 1 to October 15 extends the harvest into fall.
When to Plant Leeks in Angwin, CA
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August rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Napa County, California.
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Basket week: leeks
Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.
Leeks are a mild, sweet allium that produces long white shanks. They are more refined than onions and are a key ingredient in soups, stews, and gratins.
Angwin, California is in USDA Zone 9b. The average last spring frost is February 26 and the first fall frost is November 26, giving you a growing season of approximately 273 days.
At an elevation of 449 feet, Napa County receives approximately 35 inches of rainfall annually with predominantly loam soil. Summer highs average 88°F, providing good warmth for Leeks during the growing season.
Angwin Soil Profile
Soil Type
Loam
Soil pH
6.7-7.5
Drainage
Well Drained
Leeks 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 Angwin
How your county's soil matches Leeks's growing requirements.
Soil pH
Your soil pH (6.7–7.5) is more alkaline than Leeks prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Napa County is excellent for Leeks — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Leeks.
Organic Matter
Organic matter is moderate (3.0%). Annual compost additions will help Leeks.
How to Plant Leeks
Fall planting: Sow 8 weeks before your first frost date for a fall harvest.
Leeks Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Leeks
Leeks needs approximately 0.8 inches of water per week (3.5" per month). Here's how your county's rainfall compares month by month.
| Month | Leeks Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 7.5" | 0" | ❄️ Dormant |
| Feb | 3.5" | 7.8" | 0" | ✅ Rainfall sufficient |
| Mar | 3.5" | 5.8" | 0" | ✅ Rainfall sufficient |
| Apr | 3.5" | 2.3" | 1.2" | 💧 Light watering |
| May | 3.5" | 0.8" | 2.7" | 🚿 Regular watering |
| Jun | 3.5" | 0.2" | 3.3" | 🚿 Regular watering |
| Jul | 3.5" | 0" | 3.5" | 🚿 Regular watering |
| Aug | 3.5" | 0" | 3.5" | 🚿 Regular watering |
| Sep | 3.5" | 0.3" | 3.2" | 🚿 Regular watering |
| Oct | 3.5" | 1.3" | 2.2" | 🚿 Regular watering |
| Nov | 3.5" | 3.3" | 0.2" | 💧 Light watering |
| Dec | — | 5.6" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Feb–Nov in Napa County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Leeks 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.
Leeks Planting Timeline — Angwin, CA
Leeks Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | January 29 | Jan 29 – Feb 12 |
| Transplant Outdoors | February 26 | Feb 26 – Mar 12 |
| Direct Sow | February 5 | Feb 5 – Feb 26 |
| Harvest | May 28 | May 28 – Aug 13 |
| Fall Sowing | October 1 | Oct 1 – Oct 15 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Start Indoors |
| February | Start Indoors Transplant Outdoors Direct Sow |
| March | Transplant Outdoors |
| April | — |
| May | Harvest |
| June | Harvest |
| July | Harvest |
| August | Harvest |
| September | — |
| October | Fall Sowing |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.8"/week · 1-2 times/week
📅 Days to Maturity
90–150 days
🧪 Soil pH
Needs 6–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 9b
📆 Growing Season
273 days in Napa County
Growing Tips for Leeks in Angwin
Direct sow Leeks outdoors after February 26 in Napa County when soil has warmed and frost danger has passed.
Common pests for Leeks in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.
General growing tips
Start seeds indoors 10-12 weeks before last frost. Transplant into trenches and hill soil around stems as they grow to increase the white portion. Harvest as needed.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Leeks in Other Locations
When should I plant Leeks in Angwin, CA?
In Angwin, CA, plant Leeks after the last frost (around February 26) and before the first frost (around November 26). Best results when soil holds above 50°F.
What growing zone is Angwin, CA for Leeks?
Angwin sits in USDA Zone 9b. Leeks grows reliably in zones 3a through 10b, so it's a good fit here.
Can Leeks grow in Angwin's climate?
Yes — Leeks grows well in Angwin's temperate climate. Angwin averages a 274-day frost-free season, with last frost around February 26 and first frost around November 26.
Your Napa County Garden Planner — Free
A 22-page printable planner built for Napa 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.