When to Plant Scallions in Charleston County, SC
Your May gardening checklist
Your garden in Charleston County, South Carolina is working on a schedule, even when you're not. Here's where you should be this May.
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Harvest scallions as they ripen
Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.
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.
Charleston County, South Carolina is in USDA Zone 9a. The average last spring frost is March 6 and the first fall frost is November 17, giving you a growing season of approximately 256 days.
At an elevation of 275 feet, Charleston County receives approximately 48.1 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 95°F, so Scallions may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Scallions will need more frequent watering and organic matter to retain nutrients.
Charleston County Soil Profile
Soil Type
Sandy Loam
Soil pH
5-6
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 Charleston County
How your county's soil matches Scallions's growing requirements.
Soil pH
Your soil pH (5.0–6.0) is more acidic than Scallions prefers (6.0–7.0). Add garden lime to raise pH.
Soil Texture
Sandy soil in Charleston County warms quickly in spring but drains fast. Scallions will need more frequent watering and regular compost additions to retain nutrients.
Organic Matter
Organic matter is moderate (2.1%). 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 Sep 08 to harvest before frost.
For a dedicated fall crop, sow by Sep 22.
Plant Water Budget
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 | — | 3.9" | 0" | ❄️ Dormant |
| Feb | — | 4.2" | 0" | ❄️ Dormant |
| Mar | 4.3" | 4.8" | 0" | ✅ Rainfall sufficient |
| Apr | 4.3" | 3.1" | 1.2" | 💧 Light watering |
| May | 4.3" | 4" | 0.3" | 💧 Light watering |
| Jun | 4.3" | 4" | 0.3" | 💧 Light watering |
| Jul | 4.3" | 5.2" | 0" | ✅ Rainfall sufficient |
| Aug | 4.3" | 4.2" | 0.1" | 💧 Light watering |
| Sep | 4.3" | 4.1" | 0.2" | 💧 Light watering |
| Oct | 4.3" | 2.6" | 1.7" | 💧 Light watering |
| Nov | 4.3" | 3.7" | 0.6" | 💧 Light watering |
| Dec | — | 4.3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Mar–Nov in Charleston 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 — Charleston County, SC
Scallions Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 6 | Feb 6 – Feb 20 |
| Transplant Outdoors | March 6 | Mar 6 – Mar 20 |
| Direct Sow | February 13 | Feb 13 – Mar 6 |
| Harvest | May 1 | May 1 – May 29 |
| Fall Sowing | September 22 | Sep 22 – Oct 6 |
Plant 0.5" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors Direct Sow |
| March | Transplant Outdoors Direct Sow |
| April | — |
| May | Harvest |
| June | — |
| July | — |
| August | — |
| September | Fall Sowing |
| October | Fall Sowing |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · Only during dry spells
📅 Days to Maturity
50–70 days
🧪 Soil pH
Needs 6–7 · Your soil: too_acidic
🗺️ USDA Zone
Zone 9a
📆 Growing Season
256 days in Charleston County
Growing Tips for Scallions in Charleston County
Direct sow Scallions outdoors after March 06 in Charleston County when soil has warmed and frost danger has passed.
Sandy soil in Charleston County dries quickly — mulch Scallions with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.
Common pests for Scallions in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.
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 Charleston County, SC?
Charleston County is in Zone 9a with an average last frost of March 6. Plan your Scallions planting based on this frost date — see the calendar above for exact timing.
What planting zone is Charleston County, SC?
Charleston County, South Carolina is in USDA Hardiness Zone 9a. The average last spring frost is March 6 and first fall frost is November 17.
Your Charleston County Garden Planner — Free
A 24-page printable planner built for Charleston County (Zone 9a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.