When to Plant Napa Cabbage in Linn County, IA
This month in Linn County, Iowa
May is a pivotal month for Linn County, Iowa gardens. Focus on these tasks first and you'll set up the rest of the season for success.
-
Get napa cabbage seeds going inside
A seed-starting mix and a sunny window (or a grow light) are all you need. Keep soil warm — around 70°F — for fast germination.
Coming up in June — start thinking about
- First harvests: napa cabbage
Napa cabbage forms tall, barrel-shaped heads with tender, crinkled leaves and a mild, slightly sweet flavor. It is the primary cabbage used for kimchi.
Linn County, Iowa is in USDA Zone 5a. The average last spring frost is April 25 and the first fall frost is October 11, giving you a growing season of approximately 169 days.
At an elevation of 938 feet, Linn County receives approximately 36.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Napa Cabbage to ensure they mature before fall.
Linn County Soil Profile
Soil Type
Silt Loam
Soil pH
5.7-7.2
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 Linn County
How your county's soil matches Napa Cabbage's growing requirements.
Soil pH
Your soil pH (5.7–7.2) overlaps with Napa Cabbage's range (6.0–7.5), though not a perfect match.
Soil Texture
The silt loam soil in Linn County is excellent for Napa Cabbage — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Napa Cabbage is a heavy drinker but your soil drains very quickly. Mulch heavily and consider drip irrigation.
Organic Matter
Organic matter is excellent (4.5%) — Napa Cabbage will thrive.
How to Plant Napa Cabbage
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Succession Planting Napa Cabbage
Sow every 6.3 weeks. Last sowing by Jul 28 to harvest before frost.
For a dedicated fall crop, sow by Aug 02.
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Napa Cabbage
Napa Cabbage needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.
| Month | Napa Cabbage Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.3" | 0" | ❄️ Dormant |
| Feb | — | 1.5" | 0" | ❄️ Dormant |
| Mar | — | 2.4" | 0" | ❄️ Dormant |
| Apr | 6.5" | 3.3" | 3.2" | 💧 Light watering |
| May | 6.5" | 4.3" | 2.2" | 💧 Light watering |
| Jun | 6.5" | 4.2" | 2.3" | 💧 Light watering |
| Jul | 6.5" | 3.9" | 2.6" | 💧 Light watering |
| Aug | 6.5" | 4.3" | 2.2" | 💧 Light watering |
| Sep | 6.5" | 3.4" | 3.1" | 💧 Light watering |
| Oct | 6.5" | 3" | 3.5" | 🚿 Regular watering |
| Nov | — | 2.7" | 0" | ❄️ Dormant |
| Dec | — | 1.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Linn County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Napa Cabbage 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.
Napa Cabbage Planting Timeline — Linn County, IA
Napa Cabbage Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 21 | Mar 21 – Apr 4 |
| Transplant Outdoors | April 25 | Apr 25 – May 9 |
| Direct Sow | April 11 | Apr 11 – May 2 |
| Harvest | June 20 | Jun 20 – Jul 25 |
| Fall Sowing | August 2 | Aug 2 – Aug 16 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors Transplant Outdoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | Harvest |
| July | Harvest |
| August | Fall Sowing |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
1.5"/week · 2-3 times/week
📅 Days to Maturity
55–75 days
🧪 Soil pH
Needs 6–7.5 · Your soil: acceptable
🗺️ USDA Zone
Zone 5a
📆 Growing Season
169 days in Linn County
Growing Tips for Napa Cabbage in Linn County
Direct sow Napa Cabbage outdoors after April 25 in Linn County when soil has warmed and frost danger has passed.
Common pests for Napa Cabbage in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.
General growing tips
Best grown as a fall crop. Direct sow in late summer, 60-70 days before first frost. Keep soil evenly moist. Bolt-resistant varieties are available for spring planting.
Companion Planting
Good Companions
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Check more plant combinations with our Companion Planting Checker →
Napa Cabbage in Other Locations
Frequently Asked Questions
When should I plant Napa Cabbage in Linn County, IA?
Linn County is in Zone 5a with an average last frost of April 25. Plan your Napa Cabbage planting based on this frost date — see the calendar above for exact timing.
What planting zone is Linn County, IA?
Linn County, Iowa is in USDA Hardiness Zone 5a. The average last spring frost is April 25 and first fall frost is October 11.
Your Linn County Garden Planner — Free
A 24-page printable planner built for Linn County (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.