When to Plant Leeks in Humboldt County, CA
Your May game plan for Humboldt County, California
Your Humboldt County, California garden is entering a new phase. Here's what's on the schedule for May and why each task matters now.
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Basket week: leeks
This is the payoff month. Bring a basket, bring a friend, and get into the beds.
Coming up in June — start thinking about
- First harvests: leeks
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.
Humboldt County, 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 Leeks during the growing season. Sandy soil warms quickly in spring — great for early planting — but Leeks will need more frequent watering and organic matter to retain nutrients.
Humboldt County Soil Profile
Soil Type
Sandy Loam
Soil pH
6.2-6.8
Drainage
Well Drained
Plant 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 Humboldt County
How your county's soil matches Leeks's growing requirements.
Soil pH
Your soil pH (6.2–6.8) is within Leeks's preferred range (6.0–7.0).
Soil Texture
Sandy soil in Humboldt County warms quickly in spring but drains fast. Leeks 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 Leeks.
How to Plant Leeks
Fall planting: Sow 8 weeks before your first frost date for a fall harvest.
Plant Water Budget
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 | — | 4.8" | 0" | ❄️ Dormant |
| Feb | 3.5" | 5" | 0" | ✅ Rainfall sufficient |
| Mar | 3.5" | 3.3" | 0.2" | 💧 Light watering |
| Apr | 3.5" | 1.7" | 1.8" | 🚿 Regular watering |
| May | 3.5" | 0.5" | 3" | 🚿 Regular watering |
| Jun | 3.5" | 0.1" | 3.4" | 🚿 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" | 0.8" | 2.7" | 🚿 Regular watering |
| Nov | 3.5" | 1.9" | 1.6" | 💧 Light 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.
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 — Humboldt County, CA
Leeks Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | January 30 | Jan 30 – Feb 13 |
| Transplant Outdoors | February 27 | Feb 27 – Mar 13 |
| Direct Sow | February 6 | Feb 6 – Feb 27 |
| Harvest | May 29 | May 29 – Aug 14 |
| Fall Sowing | October 3 | Oct 3 – Oct 17 |
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: ideal
🗺️ USDA Zone
Zone 9b
📆 Growing Season
274 days in Humboldt County
Growing Tips for Leeks in Humboldt County
Direct sow Leeks outdoors after February 27 in Humboldt County when soil has warmed and frost danger has passed.
Sandy soil in Humboldt County dries quickly — mulch Leeks with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.
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
Frequently Asked Questions
When should I plant Leeks in Humboldt County, CA?
Humboldt County is in Zone 9b with an average last frost of February 27. Plan your Leeks planting based on this frost date — see the calendar above for exact timing.
What planting zone is Humboldt County, CA?
Humboldt County, California is in USDA Hardiness Zone 9b. The average last spring frost is February 27 and first fall frost is November 28.
Your Humboldt County Garden Planner — Free
A 24-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.