When to Plant Turnip in Grundy County, IA
May in the garden — Grundy County, Iowa
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.
-
Harvest turnip as they ripen
This is the payoff month. Bring a basket, bring a friend, and get into the beds.
Coming up in June — start thinking about
- First harvests: turnip
Turnips are a fast-growing cool-season root vegetable with edible roots and greens. Baby turnips are sweet and tender while mature ones are more pungent.
Grundy County, Iowa is in USDA Zone 5a. The average last spring frost is April 28 and the first fall frost is October 9, giving you a growing season of approximately 164 days.
At an elevation of 984 feet, Grundy County receives approximately 30.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Turnip to ensure they mature before fall.
Grundy County Soil Profile
Soil Type
Silt Loam
Soil pH
6-7.2
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 Grundy County
How your county's soil matches Turnip's growing requirements.
Soil pH
Your soil pH (6.0–7.2) overlaps with Turnip's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Grundy County is excellent for Turnip — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (3.9%). Annual compost additions will help Turnip.
How to Plant Turnip
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Succession Planting Turnip
Sow every 4.6 weeks. Last sowing by Aug 10 to harvest before frost.
For a dedicated fall crop, sow by Jul 31.
Plant Water Budget
Monthly Watering Guide for Turnip
Turnip needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Turnip Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.3" | 0" | ❄️ Dormant |
| Feb | — | 1.2" | 0" | ❄️ Dormant |
| Mar | — | 2.1" | 0" | ❄️ Dormant |
| Apr | 4.3" | 3.2" | 1.1" | 💧 Light watering |
| May | 4.3" | 3.3" | 1" | 💧 Light watering |
| Jun | 4.3" | 4.1" | 0.2" | 💧 Light watering |
| Jul | 4.3" | 3.1" | 1.2" | 💧 Light watering |
| Aug | 4.3" | 3.6" | 0.7" | 💧 Light watering |
| Sep | 4.3" | 2.5" | 1.8" | 💧 Light watering |
| Oct | 4.3" | 2.6" | 1.7" | 💧 Light watering |
| Nov | — | 1.9" | 0" | ❄️ Dormant |
| Dec | — | 1.5" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Grundy County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Turnip 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.
Turnip Planting Timeline — Grundy County, IA
Turnip Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | April 14 | Apr 14 – May 5 |
| Harvest | May 26 | May 26 – Jun 30 |
| Fall Sowing | July 31 | Jul 31 – Aug 14 |
Plant 0.5" deep · 4" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Direct Sow |
| May | Direct Sow Harvest |
| June | Harvest |
| July | Fall Sowing |
| August | Fall Sowing |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · Only during dry spells
📅 Days to Maturity
40–60 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 5a
📆 Growing Season
164 days in Grundy County
Growing Tips for Turnip in Grundy County
Direct sow Turnip outdoors after April 28 in Grundy County when soil has warmed and frost danger has passed.
Your generous 164.0-day season in Grundy County allows multiple plantings of Turnip. Sow every 20.0 days for continuous harvest.
Common pests for Turnip in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.
General growing tips
Direct sow in early spring or late summer. Harvest when roots are 2-3 inches in diameter for best flavor. Both the roots and the greens are nutritious and edible.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Turnip in Other Locations
Frequently Asked Questions
When should I plant Turnip in Grundy County, IA?
Grundy County is in Zone 5a with an average last frost of April 28. Plan your Turnip planting based on this frost date — see the calendar above for exact timing.
What planting zone is Grundy County, IA?
Grundy County, Iowa is in USDA Hardiness Zone 5a. The average last spring frost is April 28 and first fall frost is October 9.
Your Grundy County Garden Planner — Free
A 24-page printable planner built for Grundy 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.