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 like 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 and last several days in a vase when picked.
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 on the border they looked fully recovered.
Hydrangeas are to be found growing 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 petal-like 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 you so wish if your soil is neutral.
Here at Harlow Carr we tend to leave the heads on over the winter which gives some protection to newly forming shoots, and then 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 look quite striking together.
The whole of the white border is looking amazing at the moment so do come by and take a look, you won’t be disappointed.