When to plant Hydrangeas in Ohlman, IL
In Ohlman, Hydrangeas is a single-season spring crop — there's no second fall window. Plant April 20–May 4 for an 90–150-day harvest, finishing well before the October 21 first frost.
When to Plant Hydrangeas in Ohlman, IL
June to-do list for Montgomery County, Illinois
Welcome to June in Zone 6b. These are the moves that will have the biggest impact on your growing season.
-
Start hydrangeas indoors
These need a head start before your last frost (April 13). Sow into cells now so you're ready to transplant in a few weeks.
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Harvest hydrangeas as they ripen
This is the payoff month. Bring a basket, bring a friend, and get into the beds.
Coming up in July — start thinking about
- First harvests: hydrangeas
Hydrangeas (Hydrangea spp.) are among the most spectacular summer-blooming shrubs, with large mophead, lacecap, or panicle flower clusters lasting weeks in the garden and drying beautifully for arrangements. Native to Asia and North America alike, the genus spans several garden species with different hardiness and blooming habits. Panicle hydrangeas (H. paniculata, e.g., Limelight) are the most cold-hardy (Zone 3) and most reliable bloomers; smooth hydrangeas (H. arborescens, e.g., Annabelle) are equally tough. Bigleaf hydrangeas (H. macrophylla) are prized for blue/pink color-shifting blooms but require reliable snow cover or winter protection in Zones 5–6. Flower color in macrophylla types is determined by soil pH (acidic = blue, alkaline = pink).
Ohlman, Illinois is in USDA Zone 6b. The average last spring frost is April 13 and the first fall frost is October 21, giving you a growing season of approximately 191 days.
At an elevation of 1,331 feet, Montgomery County receives approximately 30.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88°F, providing good warmth for Hydrangeas during the growing season.
Ohlman Soil Profile
Soil Type
Silt Loam
Soil pH
6.1-7.2
Drainage
Well Drained
Hydrangeas 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 Ohlman
How your county's soil matches Hydrangeas's growing requirements.
Soil pH
Your soil pH (6.1–7.2) is more alkaline than Hydrangeas prefers (5.5–6.5). Add sulfur or peat moss to lower pH.
Soil Texture
The silt loam soil in Montgomery County is excellent for Hydrangeas — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Hydrangeas.
Organic Matter
Organic matter is excellent (5.2%) — Hydrangeas will thrive.
How to Plant Hydrangeas
Hydrangeas Water Budget
Monthly Watering Guide for Hydrangeas
Hydrangeas needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Hydrangeas Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.3" | 0" | ❄️ Dormant |
| Feb | — | 1.2" | 0" | ❄️ Dormant |
| Mar | — | 2.1" | 0" | ❄️ Dormant |
| Apr | 4.3" | 2.6" | 1.7" | 💧 Light watering |
| May | 4.3" | 3.3" | 1" | 💧 Light watering |
| Jun | 4.3" | 3.3" | 1" | 💧 Light watering |
| Jul | 4.3" | 3.7" | 0.6" | 💧 Light watering |
| Aug | 4.3" | 3.1" | 1.2" | 💧 Light watering |
| Sep | 4.3" | 3.1" | 1.2" | 💧 Light watering |
| Oct | 4.3" | 2.4" | 1.9" | 💧 Light watering |
| Nov | — | 2.1" | 0" | ❄️ Dormant |
| Dec | — | 1.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Montgomery County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Hydrangeas 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.
Hydrangeas Planting Timeline — Ohlman, IL
Hydrangeas Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 2 | Feb 2 – Feb 16 |
| Transplant Outdoors | April 20 | Apr 20 – May 4 |
| Bloom | June 29 | Jun 29 – Oct 12 |
Plant 1" deep · 48" apart · Rows 60" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | — |
| April | Transplant Outdoors |
| May | Transplant Outdoors |
| June | Bloom |
| July | Bloom |
| August | Bloom |
| September | Bloom |
| October | Bloom |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
1"/week · 1-2 times/week
📅 Days to Maturity
90–150 days
🧪 Soil pH
Needs 5.5–6.5 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 6b
📆 Growing Season
191 days in Montgomery County
Growing Tips for Hydrangeas in Ohlman
Direct sow Hydrangeas outdoors after April 13 in Montgomery County when soil has warmed and frost danger has passed.
General growing tips
Plant container-grown specimens in spring or fall, spacing at least 3–5 feet apart to allow for mature shrub spread. Most hydrangeas prefer morning sun with afternoon shade, especially in Zones 7+. Keep consistently moist — the name derives from the Greek for water vessel. Prune panicle and smooth types in late winter/early spring (they bloom on new wood). Prune bigleaf types only lightly after bloom; cutting stems in fall removes next year's buds. In Zone 5–6, protect bigleaf varieties with burlap or wire cages filled with leaves over winter. Fall planting (Zones 5+) gives excellent root establishment before summer heat. Year 2+ plants reach full size and bloom.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Hydrangeas in Other Locations
When should I plant Hydrangeas in Ohlman, IL?
In Ohlman, IL, plant Hydrangeas after the last frost (around April 13) and before the first frost (around October 21). Best results when soil holds above 50°F.
What growing zone is Ohlman, IL for Hydrangeas?
Ohlman sits in USDA Zone 6b. Hydrangeas grows reliably in zones 3a through 9a, so it's a good fit here.
Can Hydrangeas grow in Ohlman's climate?
Yes — Hydrangeas grows well in Ohlman's temperate climate. Ohlman averages a 191-day frost-free season, with last frost around April 13 and first frost around October 21.
Your Montgomery County Garden Planner — Free
A 22-page printable planner built for Montgomery 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.