When to Plant Arugula in Howard County, IA
Your May game plan for Howard County, Iowa
We've pulled the most time-sensitive tasks for Howard County, Iowa this May and put them front and centre. Tackle them in order.
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Plant out arugula
Plant tomatoes deep — bury the stem up to the first true leaves to grow extra roots. Everything else goes in at the same depth it grew in the tray.
Before June arrives, get these ready
- Starting indoors: arugula
- First harvests: arugula
Arugula is a fast-growing cool-season green with a peppery, nutty flavor. It is excellent in salads and can be harvested as baby greens or mature leaves.
Howard County, Iowa is in USDA Zone 4b. The average last spring frost is May 4 and the first fall frost is October 5, giving you a growing season of approximately 154 days.
At an elevation of 1,297 feet, Howard County receives approximately 39.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Arugula to ensure they mature before fall.
Howard County Soil Profile
Soil Type
Silt Loam
Soil pH
6.1-7.3
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 Howard County
How your county's soil matches Arugula's growing requirements.
Soil pH
Your soil pH (6.1–7.3) overlaps with Arugula's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Howard County is excellent for Arugula — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.4%) — Arugula will thrive.
How to Plant Arugula
Fall planting: Sow 12 weeks before your first frost date for a fall harvest.
Succession Planting Arugula
Sow every 3.4 weeks. Last sowing by Aug 16 to harvest before frost.
For a dedicated fall crop, sow by Jul 13.
Plant Water Budget
Monthly Watering Guide for Arugula
Arugula needs approximately 0.6 inches of water per week (2.6" per month). Here's how your county's rainfall compares month by month.
| Month | Arugula Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.8" | 0" | ❄️ Dormant |
| Feb | — | 1.7" | 0" | ❄️ Dormant |
| Mar | — | 2.8" | 0" | ❄️ Dormant |
| Apr | — | 3.9" | 0" | ❄️ Dormant |
| May | 2.6" | 4.8" | 0" | ✅ Rainfall sufficient |
| Jun | 2.6" | 4.4" | 0" | ✅ Rainfall sufficient |
| Jul | 2.6" | 4.3" | 0" | ✅ Rainfall sufficient |
| Aug | 2.6" | 4" | 0" | ✅ Rainfall sufficient |
| Sep | 2.6" | 3.5" | 0" | ✅ Rainfall sufficient |
| Oct | 2.6" | 3.3" | 0" | ✅ Rainfall sufficient |
| Nov | — | 2.5" | 0" | ❄️ Dormant |
| Dec | — | 2.6" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in Howard County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Arugula 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.
Arugula Planting Timeline — Howard County, IA
Arugula Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 23 | Mar 23 – Apr 6 |
| Transplant Outdoors | May 4 | May 4 – May 18 |
| Direct Sow | April 27 | Apr 27 – May 18 |
| Harvest | June 8 | Jun 8 – Aug 10 |
| Fall Sowing | July 13 | Jul 13 – Jul 27 |
Plant 0.5" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | Harvest |
| July | Fall Sowing Harvest |
| August | Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
0.6"/week · Natural rainfall sufficient
📅 Days to Maturity
30–50 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 4b
📆 Growing Season
154 days in Howard County
Growing Tips for Arugula in Howard County
Direct sow Arugula outdoors after May 04 in Howard County when soil has warmed and frost danger has passed.
Your generous 154.0-day season in Howard County allows multiple plantings of Arugula. Sow every 15.0 days for continuous harvest.
Common pests for Arugula in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.
General growing tips
Sow seeds directly every 2-3 weeks for continuous harvest. Provide afternoon shade in warm weather to prevent bolting. Harvest outer leaves first to extend production.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Arugula in Other Locations
Frequently Asked Questions
When should I plant Arugula in Howard County, IA?
Howard County is in Zone 4b with an average last frost of May 4. Plan your Arugula planting based on this frost date — see the calendar above for exact timing.
What planting zone is Howard County, IA?
Howard County, Iowa is in USDA Hardiness Zone 4b. The average last spring frost is May 4 and first fall frost is October 5.
Your Howard County Garden Planner — Free
A 24-page printable planner built for Howard County (Zone 4b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.