When to Plant Phlox in Delaware County, OH
Garden Phlox (Phlox paniculata) is a beloved native perennial of eastern North America, producing large, domed clusters of fragrant flowers atop upright stems from mid-summer into fall. Its sweet honey-like fragrance carries on summer evenings and draws hummingbirds, butterflies, and sphinx moths. Modern cultivars offer colors spanning white, pink, salmon, red, purple, and bicolors. A classic cottage garden stalwart, phlox combines well with black-eyed Susans, echinacea, and ornamental grasses in naturalistic plantings. Select mildew-resistant cultivars for best long-term performance.
Delaware County, Ohio is in USDA Zone 6b. The average last spring frost is April 25 and the first fall frost is October 21, giving you a growing season of approximately 179 days.
At an elevation of 1,281 feet, Delaware County receives approximately 34.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Phlox during the growing season.
Delaware County Soil Profile
Soil Type
Silt Loam
Soil pH
6.0-7.0
Drainage
Well Drained
Phlox Planting Timeline — Delaware County, OH
Phlox Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 21 | Feb 21 – Mar 7 |
| Transplant Outdoors | May 2 | May 2 – May 16 |
| Direct Sow | May 2 | May 2 – May 23 |
| Bloom | July 11 | Jul 11 – Oct 3 |
Plant 0.3" deep · 18" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Start Indoors |
| April | — |
| 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
Moderate — regular watering
📅 Days to Maturity
80–110 days
🧪 Soil pH
Needs 6–7 · Your soil: N/A
🗺️ USDA Zone
Zone 6b
📆 Growing Season
179 days in Delaware County
Growing Tips for Delaware County
Start seeds indoors 8–10 weeks before last frost, or transplant container divisions in spring. Named cultivar seeds may not come true; divisions from named plants are the preferred propagation method. Space generously (18–24 inches) and avoid overhead watering to reduce powdery mildew risk. Good air circulation is critical — thin clumps to the strongest 5–7 stems per plant in spring. Deadhead after the primary bloom flush to encourage secondary flowering. Division every 2–3 years in spring keeps plants vigorous. Fall planting of divisions (Zones 5+) is equally effective. Year 2+ plants develop into full clumps with the most prolific bloom.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Phlox in Other Locations
Frequently Asked Questions
When should I plant Phlox in Delaware County, OH?
Delaware County is in Zone 6b with an average last frost of April 25. Plan your Phlox planting based on this frost date — see the calendar above for exact timing.
What planting zone is Delaware County, OH?
Delaware County, Ohio is in USDA Hardiness Zone 6b. The average last spring frost is April 25 and first fall frost is October 21.
Your Delaware County Garden Planner — Free
A 22-page printable planner built for Delaware County (Zone 6b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.