When to Plant Scallions in Imperial County, CA
May in the garden — Imperial County, California
Each item below is timed to Imperial County, California's frost dates and soil temperatures. Skip nothing, stress about nothing.
Scallions (green onions) are mild-flavored alliums harvested for their slender green tops and white bases. They are quick-growing and perfect for succession planting.
Imperial County, California is in USDA Zone 10a. The average last spring frost is January 29 and the first fall frost is December 20, giving you a growing season of approximately 325 days.
At an elevation of 181 feet, Imperial County receives approximately 16.8 inches of rainfall annually with predominantly loam soil. Summer highs average 93°F, providing good warmth for Scallions during the growing season. With low rainfall, drip irrigation is essential for growing Scallions successfully. Mulch heavily to conserve soil moisture.
Imperial County Soil Profile
Soil Type
Loam
Soil pH
5.7-7.3
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 Imperial County
How your county's soil matches Scallions's growing requirements.
Soil pH
Your soil pH (5.7–7.3) overlaps with Scallions's range (6.0–7.0), though not a perfect match.
Soil Texture
The loam soil in Imperial County is excellent for Scallions — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.4%). Annual compost additions will help Scallions.
How to Plant Scallions
Fall planting: Sow 8 weeks before your first frost date for a fall harvest.
Succession Planting Scallions
Sow every 5.7 weeks. Last sowing by Oct 11 to harvest before frost.
For a dedicated fall crop, sow by Oct 25.
Plant Water Budget
Water stress score is 10/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Scallions
Scallions needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Scallions Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | 4.3" | 3" | 1.3" | 💧 Light watering |
| Feb | 4.3" | 3.3" | 1" | 💧 Light watering |
| Mar | 4.3" | 3.1" | 1.2" | 💧 Light watering |
| Apr | 4.3" | 1.4" | 2.9" | 🚿 Regular watering |
| May | 4.3" | 0.4" | 3.9" | 🚿 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" | 0.2" | 4.1" | 🚿 Regular watering |
| Oct | 4.3" | 0.6" | 3.7" | 🚿 Regular watering |
| Nov | 4.3" | 1.5" | 2.8" | 🚿 Regular watering |
| Dec | 4.3" | 3.3" | 1" | 💧 Light watering |
Water needs are for active growing months only (Jan–Dec in Imperial County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Scallions 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.
Scallions Planting Timeline — Imperial County, CA
Scallions Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | January 1 | Jan 1 – Jan 15 |
| Transplant Outdoors | January 29 | Jan 29 – Feb 12 |
| Direct Sow | January 8 | Jan 8 – Jan 29 |
| Harvest | March 26 | Mar 26 – Apr 23 |
| Fall Sowing | October 25 | Oct 25 – Nov 8 |
Plant 0.5" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Start Indoors Transplant Outdoors Direct Sow |
| February | Transplant Outdoors |
| March | Harvest |
| April | Harvest |
| May | — |
| June | — |
| July | — |
| August | — |
| September | — |
| October | Fall Sowing |
| November | Fall Sowing |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · 2-3 times/week
📅 Days to Maturity
50–70 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 10a
📆 Growing Season
325 days in Imperial County
Growing Tips for Scallions in Imperial County
Direct sow Scallions outdoors after January 29 in Imperial County when soil has warmed and frost danger has passed.
Common pests for Scallions in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.
Imperial County receives only 17" of rain annually. Scallions needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Direct sow every 3 weeks for continuous harvest. Thin to 1 inch apart or grow in clusters. Harvest when pencil-thick by pulling or cutting at soil level.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Scallions in Other Locations
Frequently Asked Questions
When should I plant Scallions in Imperial County, CA?
Imperial County is in Zone 10a with an average last frost of January 29. Plan your Scallions planting based on this frost date — see the calendar above for exact timing.
What planting zone is Imperial County, CA?
Imperial County, California is in USDA Hardiness Zone 10a. The average last spring frost is January 29 and first fall frost is December 20.
Your Imperial County Garden Planner — Free
A 24-page printable planner built for Imperial County (Zone 10a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.