Mops clean up
Hydrangeas are summer hit
MOPHEAD hydrangeas, or Hydrangea macrophylla, are a summertime staple useful as a backdrop for tall perennials.
They are excellent for making informal hedges too, especially in milder coastal regions as they have good tolerance of saltladen sea wind.
Well known for their very large pom- pom flower heads, which can be cut fresh for the vase or dried for winter arrangements, they can be relied on to produce a long- running show from June through to October.
This magnificent plant also has another trick up its sleeve – by the end of the summer the flowers often magically change colour. There is a myth that burying an old razor blade, rusty nails or even tea bags when planting will guarantee pink hydrangeas turn blue. It doesn’t. The colour change is affected only by the soil pH, or acidity, and only the white flowers are truly colour-fast. Those with blue or pink flowers tend to be blue in acid soil, mauve in acid to neutral soil, and pink in alkaline or limy conditions. Vintage shades as they age add to their charm. To get the best colour, you must therefore choose varieties that suit your soil type or ones that are more stable, such as Hydrangea Preziosa which produces rose-pink blooms that age to crimson-red, even in acid soils. Plant breeders are continuously hard at work looking for new varieties and this year you will find garden centres promoting the Endless Summer series and the Flair and Flavour range along with Zorro, a fabulous blue in the Royalty collection.
Mopheads thrive in sheltered borders with morning sun and afternoon shade. They hate being too dry, so put in lots of organic matter before planting and then mulch every year with a generous layer of compost.
Feeding plants with an ericaceous fertiliser in spring will help keep them lush and strengthen natural colour.
The one drawback of hydrangeas is that they produce flowers from the topmost bud of each stem. If that is damaged in winter or pruned at the wrong time, they will not flower.
Stems should only be cut back after the shrub blooms, but before flower buds form during late summer for the following year.