Has there every been a better year for hydrangeas? The wonderful rain that we have received over the last few months seems to have led to one of the best-ever displays of these stalwart shrubs in Sydney gardens. Plump Hydrangea bushes, with their bold blue or pink mopheads, were part of the landscape of my childhood. Everyone grew them, including my parents, who had a row of them on the southern side of our house where we would play on hot days. When I first started gardening, I spurned them as 'too common', but eventually I realised that they are wonderful plants for our Sydney climate, blooming over an extended period from late spring through summer, and being attractive even as their flowers age in autumn. The fact that they enjoy shady parts of the garden is an added bonus. They provide excellent cut flower material as well: pick the stems in the early morning and keep immersed in a bucket of water, up to the flower heads, for several hours before arranging in your vase. Stems picked in autumn can be dried to provide a long-lasting floral display. Remove the leaves then keep in a vase of water until the flowers become like paper.
It's true that Hydrangea can look hideous and straggly if they are neglected and unpruned, but as long as they are given some water and a bit of attention, they will reward you many times over. Their need for water can be reduced somewhat by planting them from the outset in good, compost-enriched soil and keeping them well mulched. Once they are established, they need less watering. It is best not to plant them too near to large trees with greedy roots - they grow best in the shade cast by buildings where there is no root competition. They don't mind having some morning sun - and in fact will flower better for it; it is the hot afternoon sun that will singe their leaves and burn their blooms. Refer to my plant directory entry for Hydrangea macrophylla to see more cultivation details.
The status of Hydrangea macrophylla has risen in recent years, with many fancy cultivars now available. The big domed mopheads are the most commonly seen - all mine are cuttings of the ones once grown by my parents in their mountains garden, with no identifiable names. The pretty lacecap varieties, with an outer ring of sterile florets surrounding a clustered centre of tiny fertile flowers, are very popular with gardeners at the moment. Reliable cultivars include 'Libelle' (ht 1.5 m) and 'Lanarth White' ( ht 1.5 m), both with white florets. Coloured ones are also available. I have a variegated-leaf lacecap originally grown by my grandmother in her garden for many years (possibly H. 'Maculata').
I also have an unusual Hydrangea macrophylla cultivar named 'Ayesha', which is a very strong, tough shrub, growing almost 3 m tall. I received it as a cutting from my old neighbour the day I left my previous home in Ryde. Each flower has a cupped, waxy form, a bit like a lilac - our local florist refers to it as 'popcorn Hydrangea', and each flower-head does actually look like a cup of blue (or pink!) popcorn! This is the only cultivar I know of with these unusual blooms, but perhaps there are others.
Hydrangea flowers vary from pink to blue depending on the pH of the soil - an acid soil results in blue flowers, whilst an alkaline soil gives pink blooms. I have one cultivar called 'Tosca' (pictured at left), which is said to always stay pink because it doesn't take up the aluminium in the soil, but even that one has been known to turn blue. White forms are stable. There are red ones available - I'm not sure how these fare in different soils. Various substances are available from nurseries to manipulate the colours. On the whole, the intensity of the flower colour in any particular cultivar doesn't change a lot: some are naturally pale and others more strongly coloured. There are forms which have double flowers, which are intriguing and attractive. Hydrangea heights vary from 1-3 m; many of the smaller Hydrangea can be grown in pots. I have had great success with a specimen in a container with a built-in 'water well' in recent times.
The large, lush green leaves of hydrangeas provide an effective backdrop to other plantings. I think they look best when massed together, rather than grown singly. In the long shady border in my back garden (pictured at left) where my white Hydrangea bushes are , I also grow renga renga lilies, white Justicia carnea and the unusual green and white of the bulb Albuca nelsonii, along with the silvery foliage plants Strobilanthes gossypina, Helichyrsum petiolare and Plectranthus argentatus, and some white-variegated foliage plants such as stripy Iris japonica 'Variegata'. This part of the garden is now irrigated with my grey-water system, and is the lushest it has ever been! This border only needs attention for a few hours a year and always looks OK - my own oasis of coolness like the one remembered from my childhood.
This blog originally posted on 29 November 2009; updated 15 November 2020.
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