Hydrangea macrophylla
shrubZones 5–9Beloved flowering shrub with large mophead or lacecap flower clusters that bloom blue in acidic soil and pink in alkaline soil. A cottage garden essential.
Remove only dead stems (brown and brittle). Bigleaf hydrangeas bloom on OLD WOOD so do not cut live stems or you lose this year's flowers.
For blue flowers: apply aluminum sulfate. For pink: apply garden lime. Test soil pH first (blue = pH 5.2-5.5, pink = pH 6.0-6.2).
Hydrangeas wilt dramatically when dry. Water deeply 2-3 times per week in hot weather. Morning watering is best.
Remove faded flowers by cutting just above the first set of large leaves. Do not cut further down the stem.
Do not remove dried flower heads in fall. They provide winter interest and protect flower buds from cold.
In zones 5-6, wrap plant loosely with burlap or pile leaves around it to insulate flower buds from cold damage.
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