I WAS walking past the white border the other day and was delighted to see the hydrangea arborescens ‘Annabelle’ in full bloom and looking magnificent.

This hydrangea – as a lot of them are – is well behaved and takes very little maintenance. The heads are a full eight inches (20cm) across and they have a superb creamy white sheen to them, almost the colour of clotted cream. I was very pleased to see a large vase of them in the entrance at Harlow Carr too, as they make a very good cut flower. When I checked with the team they had been knocked to the ground by the extremely heavy rain so they had picked them to save them. However, I was pleased to note that down in the border they looked fully recovered.

Hydrangeas are to be found in the woodlands of East Asia and North and South America. They are grown in the main for their large showy flower heads, which if you look at closely are actually a mixture of tiny fertile flowers and larger sterile petallike sepals.

The common hydrangea, hydrangea macrophylla, comes in two groups: the lacecap group and the hortensia group which are the mophead variety. The lacecap varieties have small fertile flowers surrounded by larger sterile flower heads whereas the mopheads just have the large sterile flowers. The blue or pink colouration is caused by the amount of aluminium ions in the soils, and the availability of that aluminium to the plant. If the pH is 5.5 or less then the colour will be blue, if it is greater than pH of 5.5, the colour will be pink. You can buy compounds which will help to change the colour of the hydrangea if your soil is neutral.

Here at Harlow Carr we tend to leave the heads on over the winter, which protects forming shoots. In the spring, just before the new buds start to break, we cut them back to a set of healthy buds to maintain a good structure, whilst removing any damaged or crossing branches. They are fully hardy and get tested most severely here as we get many extremes of weather during the winter.

On the white border, H. arborescens ‘Annabelle’ is right on a corner of the bed at the front, where it makes a very good show, and can been seen from the top path making something of a statement. Next to it are some lovely little well behaved grasses — Molinia caerula ‘Dauerstrahl’ which grow no more than three feet high, but have dark purple flowers. They are a great contrast to their blousy neighbour and the two look quite striking together.

Harlow Carr diary dates

GREAT GARDEN QUEST
Until August 31
Create an adventure to remember this summer, with activities for all the family

WILLOW SCULPTURE TRAIL
September 6-30
A new collection of willow sculptures will be installed in the garden by willow man, Phil Bradley, adding to his already muchloved pieces

SUMMER ARTS EXHIBITION
Until September 7
Beautiful works by artists from around the region

  • Events at RHS Garden Harlow Carr are free with the normal garden entrance fee, except where stated. For further information call 01423-565418.
  • RHS Garden Harlow Carr, Crag Lane, Beckwithshaw, Harrogate HG3 1QB (Sat Nave postcode HG3 1UE). Open daily from 9.30am until 6pm (4pm Nov to Feb). RHS Members free, adults £7.70 (or £8.50 including gift aid), children (five to 16) £3.85 (or £4.25 including gift aid), under-fives free. Gardens: 01423-565418; shop and plant centre: 01423-724666; Bettys tea rooms 01423-505604.

TO DO THIS WEEK

  • Clear away and burn any rose leaves that have fallen to the ground with black spot or rust to minimise the spores overwintering in the soil and re-infecting next year’s plants.
  • Keep the lawn mower blades high if there is more hot weather on the way to reduce stress to grass when cutting.
  • Bulbs will be arriving from the suppliers soon so don’t leave it until the last minute to make your choices as you want nice firm plump bulbs to ensure good spring displays.