How do I make my hydrangea flowers blue (or pink)?

Only works on H. macrophylla mophead and lacecap types. For blue: soil pH must be acid (4.5–5.5). Add aluminium sulphate or specialist hydrangea blueing agent twice a year (March and September). Ericaceous compost in pots. For pink: soil pH alkaline (7+). Add garden lime annually. White-flowered cultivars (Annabelle, Limelight, Vanille Fraise) don't change colour regardless of pH. Paniculata and arborescens types are not pH-sensitive.

When and how should I prune my hydrangea?

Crucial — depends entirely on type. Macrophylla (mophead/lacecap): light prune in March, removing only spent flowers and weak stems. Flowers on last year's wood, so heavy pruning loses next year's flowers. Paniculata: hard prune each March to a permanent framework 30 cm above ground. Flowers on this year's wood, so heavy pruning is what makes it flower. Arborescens (Annabelle): all stems to 30 cm each March. Wrong pruning for type is the single biggest cause of hydrangea problems.

Why is my hydrangea not flowering?

Most likely: wrong pruning for the type, or late frost damage to flower buds in spring. Macrophylla pruned hard like a paniculata loses all flower buds. Other causes: too much shade, too little water, over-feeding with nitrogen, or a young plant not yet established. Patience for new plants — they often skip a year while settling in.

What's the difference between mophead, lacecap, and paniculata hydrangeas?

Mophead (macrophylla): rounded heads of densely-packed sterile flowers — the classic. Pink, blue, white. Flower on last year's wood. Lacecap (macrophylla): flat heads of small fertile flowers ringed by larger sterile ones. Same plant, different flower form. Paniculata: cone-shaped flower heads — Limelight (lime-green), Vanille Fraise (white turning pink). Flower on this year's wood; pruned hard. Arborescens (Annabelle): basketball-sized round white heads. Flower on this year's wood; pruned hard.

Can I grow hydrangeas in containers?

Yes — H. macrophylla compact cultivars (Cityline series, You & Me, Endless Summer) and dwarf paniculatas (Bobo, Little Lime) suit large containers. Use 40-litre pots minimum, peat-free compost (ericaceous if maintaining blue mopheads), water daily in summer. Container hydrangeas need feeding more than ground plants — a slow-release granular feed in March and again in June.

How do I dry hydrangea flower heads?

Pick mature heads in autumn when they've turned slightly papery to the touch — usually September or October. The petals should feel papery, not soft and fresh. Cut stems 30–40 cm long; remove leaves; hang upside down in a cool dark airy place for 2 weeks. Dried hydrangeas keep their shape for 1–2 years; colours fade but the overall effect is beautiful in winter arrangements.

Ortensia

Hydrangea

Piantate le ortensie in primavera o in autunno in un terreno umido e fertile, in posizione semiombreggiata o al sole per metà della giornata. Le ortensie sono resistenti al freddo (RHS H5) e rappresentano uno degli arbusti da fiore più gratificanti per i giardini del Regno Unito. L'Hydrangea macrophylla (a fiore tondo e a fiore a cappellino) è la varietà classica: il colore dei fiori varia a seconda del pH del terreno (acido = blu, alcalino = rosa). L'H. paniculata (Limelight, Vanille Fraise) produce enormi infiorescenze a forma di cono indipendentemente dal pH. L'H. arborescens (Annabelle) produce fiori bianchi grandi come palloni da basket sui nuovi germogli. Ogni tipo ha esigenze di potatura diverse e la maggior parte dei fallimenti con le ortensie è dovuta a una potatura errata, non a una cattiva posizione. Annaffiate abbondantemente durante l'estate; pacciamate abbondantemente; concimate a marzo. Raccoglietele fresche per i vasi o essiccate le infiorescenze per le composizioni invernali.

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