When to plant Onion in Jackson County, MO
Aim to plant Onion in Jackson County on or after March 29; the window stays open through April 19. Jackson County's 197-day frost-free season gives you enough for a full main crop and a short fall succession. A second sowing from August 17 to August 31 extends the harvest into fall.
When to Plant Onion in Jackson County, MO
Your July planting checklist for Jackson County, Missouri
We've pulled the most time-sensitive tasks for Jackson County, Missouri this July and put them front and centre. Tackle them in order.
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It's harvest week for onion
The more you pick, the more the plant produces. Letting fruit overripen tells the plant it's time to stop.
Looking ahead to 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.
Jackson County, Missouri is in USDA Zone 6b. The average last spring frost is April 12 and the first fall frost is October 26, giving you a growing season of approximately 197 days.
At an elevation of 563 feet, Jackson County receives approximately 40.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Onion during the growing season.
Jackson County Soil Profile
Soil Type
Silt Loam
Soil pH
5.2-6.6
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 Jackson County
How your county's soil matches Onion's growing requirements.
Soil pH
Your soil pH (5.2–6.6) is more acidic than Onion prefers (6.0–7.0). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Jackson County is excellent for Onion — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (3.1%). Annual compost additions will help Onion.
How to Plant Onion
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Onion Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
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 | — | 1.5" | 0" | ❄️ Dormant |
| Feb | — | 1.6" | 0" | ❄️ Dormant |
| Mar | — | 3.2" | 0" | ❄️ Dormant |
| Apr | 4.3" | 4.2" | 0.1" | 💧 Light watering |
| May | 4.3" | 5.4" | 0" | ✅ Rainfall sufficient |
| Jun | 4.3" | 4.8" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 4.2" | 0.1" | 💧 Light watering |
| Aug | 4.3" | 4.1" | 0.2" | 💧 Light watering |
| Sep | 4.3" | 3.6" | 0.7" | 💧 Light watering |
| Oct | 4.3" | 2.9" | 1.4" | 💧 Light watering |
| Nov | — | 3.2" | 0" | ❄️ Dormant |
| Dec | — | 2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Jackson 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 — Jackson County, MO
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 8 | Mar 8 – Mar 22 |
| Transplant Outdoors | April 12 | Apr 12 – Apr 26 |
| Direct Sow | March 29 | Mar 29 – Apr 19 |
| Harvest | July 12 | Jul 12 – Aug 30 |
| Fall Sowing | August 17 | Aug 17 – Aug 31 |
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: too_acidic
🗺️ USDA Zone
Zone 6b
📆 Growing Season
197 days in Jackson County
Growing Tips for Onion in Jackson County
Direct sow Onion outdoors after April 12 in Jackson 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 Jackson County, MO?
Jackson County is in Zone 6b with an average last frost of April 12. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Jackson County, MO?
Jackson County, Missouri is in USDA Hardiness Zone 6b. The average last spring frost is April 12 and first fall frost is October 26.
When should I plant Onion in Jackson County, MO?
In Jackson County, MO, plant Onion after the last frost (around April 12) and before the first frost (around October 26). Best results when soil holds above 50°F.
What growing zone is Jackson County, MO for Onion?
Jackson County sits in USDA Zone 6b. Onion grows reliably in zones 3a through 10b, so it's a good fit here.
Can Onion grow in Jackson County's climate?
Yes — Onion grows well in Jackson County's temperate climate. Jackson County averages a 197-day frost-free season, with last frost around April 12 and first frost around October 26.
Your Jackson County Garden Planner — Free
A 22-page printable planner built for Jackson County (Zone 6b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.