When to Plant Onion in Beadle County, SD
May in the garden — Beadle County, South Dakota
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.
-
Move onion from tray to bed
Plant tomatoes deep — bury the stem up to the first true leaves to grow extra roots. Everything else goes in at the same depth it grew in the tray.
To set up a strong June, finish these tasks
- Starting indoors: 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.
Beadle County, South Dakota is in USDA Zone 4b. The average last spring frost is May 2 and the first fall frost is October 5, giving you a growing season of approximately 156 days.
At an elevation of 582 feet, Beadle County receives approximately 23.4 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Onion to ensure they mature before fall.
Beadle County Soil Profile
Soil Type
Loam
Soil pH
6.5-7.5
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 Beadle County
How your county's soil matches Onion's growing requirements.
Soil pH
Your soil pH (6.5–7.5) overlaps with Onion's range (6.0–7.0), though not a perfect match.
Soil Texture
The loam soil in Beadle County is excellent for Onion — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Onion.
Organic Matter
Organic matter is moderate (3.8%). Annual compost additions will help Onion.
How to Plant Onion
Fall planting: Sow 12 weeks before your first frost date for a fall harvest.
Plant 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 | — | 0.6" | 0" | ❄️ Dormant |
| Feb | — | 0.9" | 0" | ❄️ Dormant |
| Mar | — | 1.6" | 0" | ❄️ Dormant |
| Apr | — | 2.2" | 0" | ❄️ Dormant |
| May | 4.3" | 3.9" | 0.4" | 💧 Light watering |
| Jun | 4.3" | 3.4" | 0.9" | 💧 Light watering |
| Jul | 4.3" | 2.9" | 1.4" | 💧 Light watering |
| Aug | 4.3" | 2.9" | 1.4" | 💧 Light watering |
| Sep | 4.3" | 2.4" | 1.9" | 💧 Light watering |
| Oct | 4.3" | 1.5" | 2.8" | 🚿 Regular watering |
| Nov | — | 0.7" | 0" | ❄️ Dormant |
| Dec | — | 0.5" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in Beadle 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 — Beadle County, SD
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 21 | Mar 21 – Apr 4 |
| Transplant Outdoors | May 2 | May 2 – May 16 |
| Direct Sow | April 25 | Apr 25 – May 16 |
| Harvest | August 1 | Aug 1 – Sep 19 |
| Fall Sowing | July 13 | Jul 13 – Jul 27 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Fall Sowing |
| August | Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · 2-3 times/week
📅 Days to Maturity
90–120 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 4b
📆 Growing Season
156 days in Beadle County
Growing Tips for Onion in Beadle County
Direct sow Onion outdoors after May 02 in Beadle 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.
Beadle County receives only 23" of rain annually. Onion needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
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 Beadle County, SD?
Beadle County is in Zone 4b with an average last frost of May 2. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Beadle County, SD?
Beadle County, South Dakota is in USDA Hardiness Zone 4b. The average last spring frost is May 2 and first fall frost is October 5.
Your Beadle County Garden Planner — Free
A 24-page printable planner built for Beadle County (Zone 4b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.