Seasonal plants: think about hydrangeas

By Sarah Buchanan. First published by Rattan Direct on 26 June 2016.

Why think about hydrangeas?

I met a wonderful Hydrangea paniculata last summer at Greencombe gardens, West Porlock, in Somerset. This small garden, designed and planted by Joan Lorraine, is an inspiration in many ways. But it was a graceful example of this hydrangea that set me thinking about what we do wrong with hydrangeas.

We all see them: a dusty, dry and, somehow, unloved shrub with big flower heads that seem too big for the small front garden they sit in. Garden centres sell them by the dozen, small and neat, looking lush and colourful and many gardens we visit have banks of healthy hydrangeas to tempt us.

Pots of mop head hydrangeas, for sale in garden centres can, with the right care, reward us for many years. Sarah Buchanan.

So what’s going wrong with hydrangeas at home?

Like so many plants, in the right place and with the right care hydrangeas are wonderful. The small pots for sale hide their potential to grow to good sized shrubs covered in blooms for months on end. We see them at full growth in small front gardens because they do well with some shelter, and in the mix of sun and shade offerred there. But they love a moist soil with plenty of garden compost mixed into it. And that’s where we go wrong – not enough moisture. Hydranges also like light shade and some protection from late frosts, so a moist front garden can be ideal. Kept well, their flowers last for months, and when left on the plant for the winter they sparkle with frost until you ‘deadhead’ in spring.

So, if you want a hydrangea in your garden: choose a spot with some shelter (from trees, fences or buildings) from cold winds and too hot sun, make sure the soil is moist (dig in lots of garden compost), and that you can easily add water in hot dry spells. To help your front garden hydrangea, add a mulch around the plant in spring and be ready with buckets of water in hot sunny weeks.

Which variety? Would you like an ice cream cone?

There are 80 or more to choose from, offering different shapes, sizes, leaf forms and flower colours. Hydrangeas are a plant for every part of your garden. Three major varieties are likely to suit a moist soil in a sheltered spot in most gardens: mop heads, lace caps and ice cream cones.

Hydrangeas with domes or balls of white, pink, red, blue or mauve flowers are ‘mop head’ hydrangeas. ‘Lace cap’ hydrangeas have a more open and flatter flower head (which is preferred by bees). The proper name of both these varieties is Hydrangea macrophylla. These are the variety most often for sale in small pots in garden centres. Depending on where you live, they flower from late May to early autumn. Different forms offer different colours but in all the colour of the flowers is affected by the soil: an acid soil supports blue flowers, an acid to neutral soil supports mauve and an alkaline soil supports pink but white flowers tend to stay white, regardless of soil.

Pink ‘mop head’ hydrangea. Image by DonBanana, Creative Commons Attribution-Share Alike 3.0 Unported license.

If you want to buck the effect of your soil you must treat it. To create a more acid soil and blue flowers, water the plant with sequestered iron or use a blueing compound (available in garden centres). For a more alkaline soil and pink flowers, add lime or chalk (also from a garden centre). Using rainwater to water hydrangeas is important: if you have ‘hard’ (limey) tap water this may turn blue flowers mauve or pink.

Hydrangea petiolaris is a friend of north facing fences and walls, clinging without the need for wires or trellis. Bright, pale green leaves, darken in summer and turn yellow in autumn. Greeny white flowers in spring mean this plant can brighten up a darker spot where other plants may struggle. Like all hydrangeas it likes some shelter – so don’t plant it in the teeth of a North or East wind. It is likely to need pruning every few years once established (after a year or two of growth), and will reward you with years of pleasure. Depending on where you live, flowering starts in May and goes on through the early summer.

Hydrangea petiolaris, climbing up and over a garden wall, Somserset. Sarah Buchanan

Hydrangea paniculata is sometimes called the ‘ice cream cone’ hydrangea, because the flowers are shaped like that. With flowers that start a creamy white and turn pink over time, this plant is a joy from August to October. It likes more sun, and flowers start a little later, than the ‘macrophylla’ varieites, so this plant will suit a different part of your garden.

Locally grown plants
A border of hydrangea paniculata, the ice cream cone hydrangea. Frank Vincentz. Licensed under the GNU Free Documentation License, Version 1.2 and Creative Commons Attribution-Share Alike 3.0 Unported licence.

Now, are you tempted to think about planting a hydrangea this autumn?

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