🌱 Hydrangea

Grow in a deep, humus-rich, consistently moist but well-drained soil. Aim for an acidic to slightly acidic reaction (about pH 5.0–6.5 for most garden hydrangeas); avoid adding lime where blue/purple flower color is desired. Improve structure and moisture-holding by incorporating organic matter (e.g., leaf mould/composted bark) and use perlite to prevent waterlogging, especially in containers.

Seed is rarely used for named garden cultivars (offspring may not come true); hydrangeas are usually propagated by softwood or semi-ripe cuttings. For seed propagation, sow thinly on the surface of a sterile, fine seed compost (do not cover; light aids germination), keep evenly moist and warm (about 18–21°C) with high humidity, and provide bright indirect light. Prick out to pots when seedlings can be handled and grow on frost-free; plant out after hardening off once risk of frost has passed. For planting/transplanting shrubs, set at the same depth as in the pot, water in well, and mulch; best moved in cool weather (autumn or early spring).

Apply a balanced, slow-release granular feed in spring as growth starts, then (if needed) a light follow-up in early summer; stop fertilizing by mid/late summer to allow shoots to harden before winter. Avoid excessive nitrogen (promotes soft leafy growth with fewer flowers). On alkaline soils or where chlorosis occurs, use feeds that support iron/magnesium availability and maintain suitable soil acidity.

Mulch 5–8 cm over the root zone (keep mulch a few cm away from stems) to conserve moisture, moderate soil temperature, and protect shallow roots. Top up annually in spring; in colder climates, maintain a thicker mulch through winter to reduce freeze–thaw stress.

Generally self-supporting, but heavy flower heads may flop in exposed sites. If needed, use discreet ring supports or a few canes and soft ties in late spring before stems elongate; avoid tight ties that constrict stems.

Tea/infusion use is limited to the traditional ‘sweet hydrangea’ product (amacha / Hydrangeae Dulcis Folium) made from processed/fermented leaves of Hydrangea macrophylla var. thunbergii or closely related Hydrangea serrata types. Use only correctly identified, properly processed commercial material; do not use ornamental hydrangea leaves/flowers. Common preparation is a mild hot-water infusion of the dried processed leaves; follow supplier directions and avoid excessive intake due to potential toxicity and irritation.

Pruning depends on hydrangea type: for bigleaf/lacecap (H. macrophylla) and oakleaf (H. quercifolia), prune immediately after flowering by removing spent blooms and the oldest stems to the base, avoiding removal of next year’s flower buds. For panicle (H. paniculata) and smooth hydrangea (H. arborescens), prune in late winter/early spring, cutting back to a strong framework (often by 1/3–2/3) to encourage vigorous flowering shoots. In all types, remove dead, damaged, or crossing stems as needed.