When to Plant Potatoes in Johnson County, IN
Potatoes are a versatile staple crop that produces tubers underground. They come in hundreds of varieties with varying colors, textures, and maturity dates.
Johnson County, Indiana is in USDA Zone 6a. The average last spring frost is April 12 and the first fall frost is October 22, giving you a growing season of approximately 193 days.
At an elevation of 1,324 feet, Johnson County receives approximately 36.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Potatoes during the growing season.
Johnson County Soil Profile
Soil Type
Silt Loam
Soil pH
6.2-7
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 Johnson County
How your county's soil matches Potatoes's growing requirements.
Soil pH
Your soil pH (6.2–7.0) is more alkaline than Potatoes prefers (5.0–6.5). Add sulfur or peat moss to lower pH.
Soil Texture
The silt loam soil in Johnson County is excellent for Potatoes — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (5.1%) — Potatoes will thrive.
How to Plant Potatoes
Succession Planting Potatoes
Sow every 8 weeks. Last sowing by Jun 24 to harvest before frost.
Plant Water Budget
Monthly Watering Guide for Potatoes
Potatoes needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Potatoes Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.7" | 0" | ❄️ Dormant |
| Feb | — | 1.6" | 0" | ❄️ Dormant |
| Mar | — | 2.3" | 0" | ❄️ Dormant |
| Apr | 4.3" | 3.4" | 0.9" | 💧 Light watering |
| May | 4.3" | 4.6" | 0" | ✅ Rainfall sufficient |
| Jun | 4.3" | 4.1" | 0.2" | 💧 Light watering |
| Jul | 4.3" | 4.4" | 0" | ✅ Rainfall sufficient |
| Aug | 4.3" | 4" | 0.3" | 💧 Light watering |
| Sep | 4.3" | 3.1" | 1.2" | 💧 Light watering |
| Oct | 4.3" | 2.9" | 1.4" | 💧 Light watering |
| Nov | — | 2.2" | 0" | ❄️ Dormant |
| Dec | — | 2.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Johnson County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Potatoes 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.
Potatoes Planting Timeline — Johnson County, IN
Potatoes Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 15 | Feb 15 – Mar 1 |
| Transplant Outdoors | April 26 | Apr 26 – May 10 |
| Direct Sow | April 19 | Apr 19 – May 10 |
| Harvest | July 5 | Jul 5 – Sep 13 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Start Indoors |
| April | Transplant Outdoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · Only during dry spells
📅 Days to Maturity
70–120 days
🧪 Soil pH
Needs 5–6.5 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 6a
📆 Growing Season
193 days in Johnson County
Growing Tips for Potatoes in Johnson County
Direct sow Potatoes outdoors after April 12 in Johnson County when soil has warmed and frost danger has passed.
Common pests for Potatoes in this region include tomato hornworm and aphids. Use row covers early in the season and inspect plants weekly.
General growing tips
Plant seed potatoes (not grocery store potatoes) 4 inches deep in spring. Hill soil around stems as plants grow to prevent greening. Stop watering when plants die back.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Potatoes in Other Locations
Frequently Asked Questions
When should I plant Potatoes in Johnson County, IN?
Johnson County is in Zone 6a with an average last frost of April 12. Plan your Potatoes planting based on this frost date — see the calendar above for exact timing.
What planting zone is Johnson County, IN?
Johnson County, Indiana is in USDA Hardiness Zone 6a. The average last spring frost is April 12 and first fall frost is October 22.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Johnson County gardeners in Zone 6a organize planting dates, track what's growing, and never miss a planting window.
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