When to plant Onion in Clark County, IN
For Onion in Clark County, the safe spring window opens around March 27 and closes around April 17. Last expected frost is April 10, first fall frost October 22, giving a 195-day growing season. A second sowing from August 13 to August 27 extends the harvest into fall.
When to Plant Onion in Clark County, IN
July in Clark County, Indiana — your action list
Welcome to July in Zone 7a. These are the moves that will have the biggest impact on your growing season.
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Basket week: onion
Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.
A few tasks this July that'll pay off in August
- First harvests: onion
- Fall sowing: onion
Onions are a fundamental kitchen staple available in yellow, white, and red varieties. Choose long-day, short-day, or intermediate types based on your latitude.
Clark County, Indiana is in USDA Zone 7a. The average last spring frost is April 10 and the first fall frost is October 22, giving you a growing season of approximately 195 days.
At an elevation of 1,265 feet, Clark County receives approximately 36.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Onion during the growing season.
Clark County Soil Profile
Soil Type
Silt Loam
Soil pH
5.8-6.7
Drainage
Well Drained
Onion 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 Clark County
How your county's soil matches Onion's growing requirements.
Soil pH
Your soil pH (5.8–6.7) overlaps with Onion's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Clark County is excellent for Onion — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.3%) — Onion will thrive.
How to Plant Onion
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Onion Water Budget
Monthly Watering Guide for Onion
Onion needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Onion Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.4" | 0" | ❄️ Dormant |
| Feb | — | 1.5" | 0" | ❄️ Dormant |
| Mar | — | 2.9" | 0" | ❄️ Dormant |
| Apr | 4.3" | 3.8" | 0.5" | 💧 Light watering |
| May | 4.3" | 4.5" | 0" | ✅ Rainfall sufficient |
| Jun | 4.3" | 4.5" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 4.1" | 0.2" | 💧 Light watering |
| Aug | 4.3" | 3.5" | 0.8" | 💧 Light watering |
| Sep | 4.3" | 2.8" | 1.5" | 💧 Light watering |
| Oct | 4.3" | 3" | 1.3" | 💧 Light watering |
| Nov | — | 3" | 0" | ❄️ Dormant |
| Dec | — | 2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Clark County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Onion 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.
Onion Planting Timeline — Clark County, IN
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 6 | Mar 6 – Mar 20 |
| Transplant Outdoors | April 10 | Apr 10 – Apr 24 |
| Direct Sow | March 27 | Mar 27 – Apr 17 |
| Harvest | July 10 | Jul 10 – Aug 28 |
| Fall Sowing | August 13 | Aug 13 – Aug 27 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors Direct Sow |
| April | Transplant Outdoors Direct Sow |
| May | — |
| June | — |
| July | Harvest |
| August | Fall Sowing Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · Only during dry spells
📅 Days to Maturity
90–120 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 7a
📆 Growing Season
195 days in Clark County
Growing Tips for Onion in Clark County
Direct sow Onion outdoors after April 10 in Clark County when soil has warmed and frost danger has passed.
Common pests for Onion 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 8-10 weeks before transplanting. Match day-length type to your latitude. Stop watering when tops begin to fall over and cure bulbs for 2-3 weeks before storage.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Onion in Other Locations
Frequently Asked Questions
When should I plant Onion in Clark County, IN?
Clark County is in Zone 7a with an average last frost of April 10. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Clark County, IN?
Clark County, Indiana is in USDA Hardiness Zone 7a. The average last spring frost is April 10 and first fall frost is October 22.
When should I plant Onion in Clark County, IN?
In Clark County, IN, plant Onion after the last frost (around April 10) and before the first frost (around October 22). Best results when soil holds above 50°F.
What growing zone is Clark County, IN for Onion?
Clark County sits in USDA Zone 7a. Onion grows reliably in zones 3a through 10b, so it's a good fit here.
Can Onion grow in Clark County's climate?
Yes — Onion grows well in Clark County's temperate climate. Clark County averages a 195-day frost-free season, with last frost around April 10 and first frost around October 22.
Your Clark County Garden Planner — Free
A 22-page printable planner built for Clark County (Zone 7a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.