When to Plant Leeks in Cumberland County, NJ
Your May gardening checklist
If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.
-
Indoor seed-starting week for leeks
A seed-starting mix and a sunny window (or a grow light) are all you need. Keep soil warm — around 70°F — for fast germination.
June prep starts now
- 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.
Cumberland County, New Jersey is in USDA Zone 7b. The average last spring frost is March 28 and the first fall frost is November 12, giving you a growing season of approximately 229 days.
At an elevation of 425 feet, Cumberland County receives approximately 42 inches of rainfall annually with predominantly silt loam soil. Summer highs average 94°F, providing good warmth for Leeks during the growing season.
Cumberland County Soil Profile
Soil Type
Silt Loam
Soil pH
5.2-6.8
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 Cumberland County
How your county's soil matches Leeks's growing requirements.
Soil pH
Your soil pH (5.2–6.8) overlaps with Leeks's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Cumberland County is excellent for Leeks — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (3.7%). Annual compost additions will help Leeks.
How to Plant Leeks
Fall planting: Sow 10 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 | — | 3.4" | 0" | ❄️ Dormant |
| Feb | — | 2.8" | 0" | ❄️ Dormant |
| Mar | 3.5" | 3.5" | 0" | ✅ Rainfall sufficient |
| Apr | 3.5" | 3.4" | 0.1" | 💧 Light watering |
| May | 3.5" | 4.4" | 0" | ✅ Rainfall sufficient |
| Jun | 3.5" | 3.8" | 0" | ✅ Rainfall sufficient |
| Jul | 3.5" | 4.1" | 0" | ✅ Rainfall sufficient |
| Aug | 3.5" | 3.9" | 0" | ✅ Rainfall sufficient |
| Sep | 3.5" | 3.3" | 0.2" | 💧 Light watering |
| Oct | 3.5" | 3.6" | 0" | ✅ Rainfall sufficient |
| Nov | 3.5" | 3.1" | 0.4" | 💧 Light watering |
| Dec | — | 2.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Mar–Nov in Cumberland 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 — Cumberland County, NJ
Leeks Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 21 | Feb 21 – Mar 7 |
| Transplant Outdoors | March 28 | Mar 28 – Apr 11 |
| Direct Sow | March 14 | Mar 14 – Apr 4 |
| Harvest | June 27 | Jun 27 – Sep 12 |
| Fall Sowing | September 3 | Sep 3 – Sep 17 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Start Indoors Transplant Outdoors Direct Sow |
| April | Transplant Outdoors Direct Sow |
| May | — |
| June | Harvest |
| July | Harvest |
| August | Harvest |
| September | Fall Sowing Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.8"/week · Only during dry spells
📅 Days to Maturity
90–150 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 7b
📆 Growing Season
229 days in Cumberland County
Growing Tips for Leeks in Cumberland County
Direct sow Leeks outdoors after March 28 in Cumberland 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
Frequently Asked Questions
When should I plant Leeks in Cumberland County, NJ?
Cumberland County is in Zone 7b with an average last frost of March 28. Plan your Leeks planting based on this frost date — see the calendar above for exact timing.
What planting zone is Cumberland County, NJ?
Cumberland County, New Jersey is in USDA Hardiness Zone 7b. The average last spring frost is March 28 and first fall frost is November 12.
Your Cumberland County Garden Planner — Free
A 24-page printable planner built for Cumberland County (Zone 7b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.