When to plant Black-eyed Susan in Audubon County County,
Audubon County County gardeners should plant Black-eyed Susan between April 28 and May 19 in spring. With Audubon County County's Zone 5a climate (last frost April 28), Black-eyed Susan needs 80 days to mature — plant by July 15 for a full harvest.
When to Plant Black-eyed Susan in Audubon County, IA
Your June gardening checklist
Your garden in Audubon County, Iowa is working on a schedule, even when you're not. Here's where you should be this June.
-
Time to start black-eyed susan inside
Starting these indoors now means sturdy transplants ready the moment your soil warms up.
To set up a strong July, finish these tasks
- First harvests: black-eyed susan
Rudbeckia hirta (Black-eyed Susan) is one of the most recognizable and adaptable native wildflowers in North America. Its bright golden-yellow daisy petals radiate from a dark brown central cone, providing months of color from midsummer into fall. Technically a short-lived perennial that self-seeds freely — colonies persist indefinitely in the garden — it thrives in poor soils, tolerates drought, and is irresistible to bees, butterflies, and goldfinches.
Audubon County, Iowa is in USDA Zone 5a. The average last spring frost is April 28 and the first fall frost is October 3, giving you a growing season of approximately 158 days.
At an elevation of 1,056 feet, Audubon County receives approximately 32.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Black-eyed Susan during the growing season.
Audubon County Soil Profile
Soil Type
Silt Loam
Soil pH
5.8-6.8
Drainage
Well Drained
Black-eyed Susan 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 Audubon County
How your county's soil matches Black-eyed Susan's growing requirements.
Soil pH
Your soil pH (5.8–6.8) overlaps with Black-eyed Susan's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Audubon County is excellent for Black-eyed Susan — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.8%) — Black-eyed Susan will thrive.
How to Plant Black-eyed Susan
Succession Planting Black-eyed Susan
Sow every 6.9 weeks. Last sowing by Jul 15 to harvest before frost.
Black-eyed Susan Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Black-eyed Susan
Black-eyed Susan needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.
| Month | Black-eyed Susan Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.3" | 0" | ❄️ Dormant |
| Feb | — | 1.3" | 0" | ❄️ Dormant |
| Mar | — | 2.1" | 0" | ❄️ Dormant |
| Apr | 2.2" | 3.2" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 4.4" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 3.7" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 3.9" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 3.5" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 2.6" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 2.6" | 0" | ✅ Rainfall sufficient |
| Nov | — | 2" | 0" | ❄️ Dormant |
| Dec | — | 1.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Audubon County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Black-eyed Susan 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.
Black-eyed Susan Planting Timeline — Audubon County, IA
Black-eyed Susan Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 24 | Feb 24 – Mar 10 |
| Transplant Outdoors | May 12 | May 12 – May 26 |
| Direct Sow | April 28 | Apr 28 – May 19 |
| Bloom | July 28 | Jul 28 – Oct 27 |
· 18" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Start Indoors |
| April | Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Bloom |
| August | Bloom |
| September | Bloom |
| October | Bloom |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Natural rainfall sufficient
📅 Days to Maturity
60–80 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 5a
📆 Growing Season
158 days in Audubon County
Growing Tips for Black-eyed Susan in Audubon County
Direct sow Black-eyed Susan outdoors after April 28 in Audubon County when soil has warmed and frost danger has passed.
Common pests for Black-eyed Susan in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.
General growing tips
Start seeds indoors 8–10 weeks before last frost or direct-sow after last frost (needs light to germinate — press seeds onto soil surface, do not cover). Thrives in average to poor soil; rich soil causes floppy stems. Deadhead for extended bloom but leave some seed heads for winter wildlife interest and self-seeding. Although technically short-lived (3–5 years), prolific self-seeding maintains the colony. Year 2+ plants bloom most heavily. Divide every 3 years to maintain vigor.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Black-eyed Susan in Other Locations
Frequently Asked Questions
When should I plant Black-eyed Susan in Audubon County, IA?
Audubon County is in Zone 5a with an average last frost of April 28. Plan your Black-eyed Susan planting based on this frost date — see the calendar above for exact timing.
What planting zone is Audubon County, IA?
Audubon County, Iowa is in USDA Hardiness Zone 5a. The average last spring frost is April 28 and first fall frost is October 3.
When should I plant Black-eyed Susan in Audubon County County, ?
In Audubon County County, , plant Black-eyed Susan after the last frost (around April 28) and before the first frost (around October 3). Best results when soil holds above 50°F.
What growing zone is Audubon County County, for Black-eyed Susan?
Audubon County County sits in USDA Zone 5a. Black-eyed Susan grows reliably in zones 3a through 9b, so it's a good fit here.
Can Black-eyed Susan grow in Audubon County County's climate?
Yes — Black-eyed Susan grows well in Audubon County County's temperate climate. Audubon County County averages a 158-day frost-free season, with last frost around April 28 and first frost around October 3.
Your Audubon County Garden Planner — Free
A 22-page printable planner built for Audubon 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.