Hydrangea Growing Guide
Hydrangea species, Hydrangea macrophylla (bigleaf hydrangea), Hydrangea paniculata (panicled hydrangea), Hydrangea arborescens (hills of snow, Annabelle hydrangea), Hydrangea anomala petiolaris (climbing hydrangea) and Hydrangea quercifolia (oakleaf hydrangea)
Crop Rotation Group
Moist, well-drained soil enriched with plenty of compost or other organic matter. The soil pH affects the flower colour of bigleaf hydrangea. Highly acidic soils turn flowers blue, while pink predominates in alkaline soils. Many modern varieties are less sensitive to soil pH changes.
Full sun to part shade. Large, white-flowered panicle hydrangeas can be grown as specimen shrubs in a sunny lawn, or pruned to grow as sculpted small trees. colourful bigleaf hydrangeas are often damaged by winter cold, so they are best grown in sheltered spots with part-day shade. Oakleaf hydrangea grows best in partial shade.
Cold tolerance varies with species, with some hardy to -26°C (-15°F). Popular bigleaf hydrangeas are often injured by winter temperatures below -12°C (10°F).
Boosting soil fertility results in bigger, better hydrangea flower clusters. Topdress the root zone with rotted manure topped by an organic mulch in winter. Or, apply a balanced organic fertiliser twice yearly, once in spring and again in early summer.
Single Plants: 1.50m (4' 11") each way (minimum)
Rows: 1.50m (4' 11") with 1.50m (4' 11") row gap (minimum)
Sow and Plant
Set out purchased plants in spring at about the time of your last frost. Container-grown plants can be set out through early summer. Water regularly, and cover the root zone with an organic mulch to keep the soil moist at all times. Spacing varies with the type grown, but hydrangeas should usually be grown at least 1.5m (5 feet) apart. Hydrangeas often are grown as single specimen plants, or several may be used to structure woodland landscapes. Check plant tags for a plant’s mature width when planting hydrangeas as hedges or in combination with other shrubs.
Our Garden Planner can produce a personalized calendar of when to sow, plant and harvest for your area.
Visit local display gardens to learn about the best hydrangeas for your area. If you admire hydrangeas growing in neighbours’ yards, check with local garden centres for matching plants. Take your time making choices, because hydrangeas are large, long-lived shrubs that will be with you for many years. The need to prune varies with species, but most hydrangeas can be pruned to shape them and control their size in early winter or in spring. Delay hard pruning of bigleaf hydrangea until mid-spring, when you can see which buds survived winter.
Hydrangea petals are actually dry bracts, so the clusters are easy to dry. Cut hydrangeas for drying after the colours have begun to fade. Allow the stems to dry naturally in a dry vase for two weeks.
Hydrangeas may show leaf spots from various fungi, but they are seldom troubled by insects or devastating diseases. Lack of bloom is often caused by winter injury or insufficient pruning. Should rabbits nibble hydrangeas in winter, protect plants with wire cages.
Planting and Harvesting Calendar
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