When to plant Hydrangeas in Union County, MS
In Union County, Hydrangeas is a single-season spring crop — there's no second fall window. Plant March 30–April 13 for an 90–150-day harvest, finishing well before the October 29 first frost.
When to Plant Hydrangeas in Union County, MS
Top priorities for Union County, Mississippi gardeners in June
Your Union County, Mississippi garden is entering a new phase. Here's what's on the schedule for June and why each task matters now.
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Fire up the seed-starting tray: hydrangeas
Your window is short. These crops want several weeks of indoor growth before they go outside.
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Collect hydrangeas at their peak
Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.
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).
Union County, Mississippi is in USDA Zone 8a. The average last spring frost is March 30 and the first fall frost is October 29, giving you a growing season of approximately 213 days.
At an elevation of 196 feet, Union County receives approximately 49.9 inches of rainfall annually with predominantly clay loam soil. Summer highs average 94°F, providing good warmth for Hydrangeas during the growing season. Clay soil retains moisture well for Hydrangeas, but amend with compost to improve drainage and prevent root rot.
Union County Soil Profile
Soil Type
Clay Loam
Soil pH
5.3-6.8
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 Union County
How your county's soil matches Hydrangeas's growing requirements.
Soil pH
Your soil pH (5.3–6.8) overlaps with Hydrangeas's range (5.5–6.5), though not a perfect match.
Soil Texture
The clay loam soil in Union County is excellent for Hydrangeas — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.3%). Annual compost additions will help Hydrangeas.
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 | — | 3.8" | 0" | ❄️ Dormant |
| Feb | — | 3.8" | 0" | ❄️ Dormant |
| Mar | 4.3" | 5.2" | 0" | ✅ Rainfall sufficient |
| Apr | 4.3" | 3.6" | 0.7" | 💧 Light watering |
| May | 4.3" | 4.6" | 0" | ✅ Rainfall sufficient |
| Jun | 4.3" | 4.8" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 5.1" | 0" | ✅ Rainfall sufficient |
| Aug | 4.3" | 4.6" | 0" | ✅ Rainfall sufficient |
| Sep | 4.3" | 3.4" | 0.9" | 💧 Light watering |
| Oct | 4.3" | 3.2" | 1.1" | 💧 Light watering |
| Nov | — | 3.6" | 0" | ❄️ Dormant |
| Dec | — | 4.1" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Mar–Oct in Union 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 — Union County, MS
Hydrangeas Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | January 26 | Jan 26 – Feb 9 |
| Transplant Outdoors | March 30 | Mar 30 – Apr 13 |
| Bloom | June 8 | Jun 8 – Oct 12 |
Plant 1" deep · 48" apart · Rows 60" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Start Indoors |
| February | Start Indoors |
| March | Transplant Outdoors |
| April | Transplant Outdoors |
| May | — |
| June | Bloom |
| July | Bloom |
| August | Bloom |
| September | Bloom |
| October | Bloom |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
1"/week · Only during dry spells
📅 Days to Maturity
90–150 days
🧪 Soil pH
Needs 5.5–6.5 · Your soil: acceptable
🗺️ USDA Zone
Zone 8a
📆 Growing Season
213 days in Union County
Growing Tips for Hydrangeas in Union County
Direct sow Hydrangeas outdoors after March 30 in Union County when soil has warmed and frost danger has passed.
With Union County's clay soil (29% clay), work in 3-4 inches of compost before planting Hydrangeas. Avoid tilling when soil is wet to prevent compaction.
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
Frequently Asked Questions
When should I plant Hydrangeas in Union County, MS?
Union County is in Zone 8a with an average last frost of March 30. Plan your Hydrangeas planting based on this frost date — see the calendar above for exact timing.
What planting zone is Union County, MS?
Union County, Mississippi is in USDA Hardiness Zone 8a. The average last spring frost is March 30 and first fall frost is October 29.
When should I plant Hydrangeas in Union County, MS?
In Union County, MS, plant Hydrangeas after the last frost (around March 30) and before the first frost (around October 29). Best results when soil holds above 50°F.
What growing zone is Union County, MS for Hydrangeas?
Union County sits in USDA Zone 8a. Hydrangeas grows reliably in zones 3a through 9a, so it's a good fit here.
Can Hydrangeas grow in Union County's climate?
Yes — Hydrangeas grows well in Union County's temperate climate. Union County averages a 213-day frost-free season, with last frost around March 30 and first frost around October 29.
Your Union County Garden Planner — Free
A 22-page printable planner built for Union County (Zone 8a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.