Hydrangea planting and care instructions

Pink and blue hydrangeas require different soil types.
ARTICLE Patricia Moore

The most common varieties are the macrophyllas, the leafy pink and blue mop-heads and lacecaps, which grow well when exposed to the sun in the morning, but need the afternoon shade to produce flowers that will last. Ensure they have room to grow; dwarf varieties will grow to a maximum height of 90cm, standard varieties up to two metres.

Hydrangeas are thirsty plants – in fact ‘hydrangea’ comes from the Greek word for water tub – and grow best in well-worked fertile soil. Dig in plenty of compost when planting and mulch well.

The colour of hydrangea blooms is dictated by the soil type; an alkaline soil will deliver pink flowers, whereas an acid soil will result in blue blooms. Apply lime to encourage pink or red toned flowers and aluminium sulphate for the blue shades. Achieving the desired depth of colour won’t happen overnight – it may require two or three applications per growing season. White hydrangeas do not usually respond to this process.

Hydrangeas require minimum care. Keep them watered over summer, use a general garden fertiliser in late autumn and prune back to around half size in autumn. To encourage flower growth for the next season, cut just above a pair of fat nodes. Pruning’s can be trimmed to around 20 to 30cm and planted in potting mix or straight into prepared soil for new plants.

Lack of flowers can often be the result of poor fertilisation or too much shade. Pests are seldom a problem with hydrangeas, but they can be affected by powdery mildew, which shows as a white powder on the leaves and causes them to yellow and wilt. The infected parts should be removed and the shrub sprayed with a fungicide.

Hydrangea Valley, a feature of sub-tropical Trebah Garden in Cornwall, left a lasting impression on a landscape designer at Zones Landscaping Specialists. “Two acres of massed blooms spill down the Valley towards the sea, the effect mirrored in the Mallard Pond at the Valley house. The beauty in the repetition of colour and texture was powerful.” (The blooms of the hydrangeas in the Valley - which were planted over 50 years ago and still flower annually – were sent to Covent Garden flower market and became a source of income for the garden).

The landscape designer likes to use hydrangeas to chase tree-lined driveways and as a backdrop to ponds and water bodies. “Their colouration and romantic effect is particularly well suited to villa gardens and rural lifestyle properties.”

A little known fact; hydrangea exports are worth around 3 million dollars to New Zealand, ranking second only to cymbidium orchids. They’ve been described as ‘very much a party flower that fills up a lot of space’ – something which would have been needed for the 40,000 purple hydrangea heads one local exporter shipped for a wedding in Saudi Arabia.

You might be interested in reading: How to create a bee-friendly garden.

This article by Patricia Moore featured in Issue 019 of New Zealand Renovate Magazine. New Zealand's first and only magazine solely dedicated to home renovations.

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*All information is believed to be true at time of publishing and is subject to change.

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