When to Plant Sunchoke in Johnson County, KS
Sunchokes (Jerusalem artichokes) are a native sunflower relative grown for their knobby, nutty-flavored tubers. They are extremely productive and nearly impossible to eradicate.
Johnson County, Kansas is in USDA Zone 6a. The average last spring frost is April 8 and the first fall frost is October 26, giving you a growing season of approximately 201 days.
At an elevation of 768 feet, Johnson County receives approximately 27.6 inches of rainfall annually with predominantly loam soil. Summer highs average 87°F, providing good warmth for Sunchoke during the growing season.
Johnson County Soil Profile
Soil Type
Loam
Soil pH
6.8-7.2
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 Sunchoke's growing requirements.
Soil pH
Your soil pH (6.8–7.2) is within Sunchoke's preferred range (6.0–7.5).
Soil Texture
The loam soil in Johnson County is excellent for Sunchoke — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.2%) — Sunchoke will thrive.
How to Plant Sunchoke
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Sunchoke
Sunchoke needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Sunchoke Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 0.8" | 0" | ❄️ Dormant |
| Feb | — | 0.8" | 0" | ❄️ Dormant |
| Mar | — | 1.9" | 0" | ❄️ Dormant |
| Apr | 4.3" | 3.2" | 1.1" | 💧 Light watering |
| May | 4.3" | 3.7" | 0.6" | 💧 Light watering |
| Jun | 4.3" | 4.1" | 0.2" | 💧 Light watering |
| Jul | 4.3" | 3.8" | 0.5" | 💧 Light watering |
| Aug | 4.3" | 3.5" | 0.8" | 💧 Light watering |
| Sep | 4.3" | 2.3" | 2" | 💧 Light watering |
| Oct | 4.3" | 1.8" | 2.5" | 🚿 Regular watering |
| Nov | — | 1" | 0" | ❄️ Dormant |
| Dec | — | 0.7" | 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.
Sunchoke 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.
Sunchoke Planting Timeline — Johnson County, KS
Sunchoke Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | April 22 | Apr 22 – May 6 |
| Harvest | August 12 | Aug 12 – Oct 7 |
Plant 1" deep · 30" apart · Rows 42" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Transplant Outdoors |
| May | Transplant Outdoors |
| June | — |
| July | — |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · 1-2 times/week
📅 Days to Maturity
110–150 days
🧪 Soil pH
Needs 6–7.5 · Your soil: ideal
🗺️ USDA Zone
Zone 6a
📆 Growing Season
201 days in Johnson County
Growing Tips for Sunchoke in Johnson County
Direct sow Sunchoke outdoors after April 08 in Johnson County when soil has warmed and frost danger has passed.
Common pests for Sunchoke in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.
General growing tips
Plant tubers 4 inches deep in early spring. Contain plants with barriers as they spread aggressively. Harvest after frost or leave in ground and dig as needed through winter.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Sunchoke in Other Locations
Frequently Asked Questions
When should I plant Sunchoke in Johnson County, KS?
Johnson County is in Zone 6a with an average last frost of April 8. Plan your Sunchoke planting based on this frost date — see the calendar above for exact timing.
What planting zone is Johnson County, KS?
Johnson County, Kansas is in USDA Hardiness Zone 6a. The average last spring frost is April 8 and first fall frost is October 26.
Plan Your Garden with Confidence
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