When to Plant Leeks in Todd County, SD
Leeks are a mild, sweet allium that produces long white shanks. They are more refined than onions and are a key ingredient in soups, stews, and gratins.
Todd County, South Dakota is in USDA Zone 4b. The average last spring frost is May 6 and the first fall frost is October 6, giving you a growing season of approximately 153 days.
At an elevation of 1,071 feet, Todd County receives approximately 28 inches of rainfall annually with predominantly loam soil. Summer highs average 83°F, so choose short-season varieties of Leeks to ensure they mature before fall.
Todd County Soil Profile
Soil Type
Loam
Soil pH
6.4-7.4
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 Todd County
How your county's soil matches Leeks's growing requirements.
Soil pH
Your soil pH (6.4–7.4) overlaps with Leeks's range (6.0–7.0), though not a perfect match.
Soil Texture
The loam soil in Todd County is excellent for Leeks — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Leeks.
Organic Matter
Organic matter is moderate (3.8%). Annual compost additions will help Leeks.
How to Plant Leeks
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 Leeks
Leeks needs approximately 0.8 inches of water per week (3.5" per month). Here's how your county's rainfall compares month by month.
| Month | Leeks Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.8" | 0" | ❄️ Dormant |
| Feb | — | 1.8" | 0" | ❄️ Dormant |
| Mar | — | 2.4" | 0" | ❄️ Dormant |
| Apr | — | 2.6" | 0" | ❄️ Dormant |
| May | 3.5" | 3.6" | 0" | ✅ Rainfall sufficient |
| Jun | 3.5" | 2.2" | 1.3" | 💧 Light watering |
| Jul | 3.5" | 2.7" | 0.8" | 💧 Light watering |
| Aug | 3.5" | 2.8" | 0.7" | 💧 Light watering |
| Sep | 3.5" | 2.3" | 1.2" | 💧 Light watering |
| Oct | 3.5" | 2.1" | 1.4" | 💧 Light watering |
| Nov | — | 2" | 0" | ❄️ Dormant |
| Dec | — | 1.5" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in Todd County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Leeks 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.
Leeks Planting Timeline — Todd County, SD
Leeks Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 25 | Mar 25 – Apr 8 |
| Transplant Outdoors | May 6 | May 6 – May 20 |
| Direct Sow | April 29 | Apr 29 – May 20 |
| Harvest | August 5 | Aug 5 – Sep 30 |
| Fall Sowing | July 14 | Jul 14 – Jul 28 |
Plant 1" deep · 15" apart · Rows 24" 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
0.8"/week · 1-2 times/week
📅 Days to Maturity
90–150 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 4b
📆 Growing Season
153 days in Todd County
Growing Tips for Leeks in Todd County
Direct sow Leeks outdoors after May 06 in Todd County when soil has warmed and frost danger has passed.
Your 153.0-day growing season in Todd County is tight for Leeks (90.0-150.0 days to maturity). Start indoors and choose early-maturing varieties.
Common pests for Leeks 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 10-12 weeks before last frost. Transplant into trenches and hill soil around stems as they grow to increase the white portion. Harvest as needed.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Leeks in Other Locations
Frequently Asked Questions
When should I plant Leeks in Todd County, SD?
Todd County is in Zone 4b with an average last frost of May 6. Plan your Leeks planting based on this frost date — see the calendar above for exact timing.
What planting zone is Todd County, SD?
Todd County, South Dakota is in USDA Hardiness Zone 4b. The average last spring frost is May 6 and first fall frost is October 6.
Plan Your Garden with Confidence
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