Summer seems a long time gone, although its aftermath is still present in some of the garden plants.
Yes, the summer bedding plants in our garden have all been lifted and taken to a local authority recycling facility to be composted. And yes, the majority of the shrubs have been pruned and trimmed ready for winter, dead shoots and stray shoots cut out or cut back. But several shrubs still carry the faded remnants of once-glorious late summer and early autumn blooms, for these are hydrangeas which should be allowed to overwinter in the same state as they were at winter’s onset, pruning being left until the following spring.
To be more precise, the shrubs in my garden are Hydrangea macrophylla - the member of the family of plants distinguished by their cup-shaped fruits … Hydrangea, from the Greek words hydor, meaning ‘water’, and aggos, meaning ‘a cup’ … which have large leaves – macrophylla. Members of this particular species come with different what I might call ‘flower styles’ … mophead and lacecap … and what truly descriptive names these are, for there can be no doubt to which subset any particular plant belongs for much of the year.
One particular hydrangea which I can see from where I am sitting is a large, mature lacecap specimen … I don’t know which sub-species of Hydrangea macrophylla it belongs to … which distinguished itself during its long principal flowering season by carrying an absolute profusion of vibrant blue flowers. The lacecap hydrangeas are generally credited with having been introduced to Europe by Charles Maries, a foreman gardener in the Veitch Nurseries in Chelsea, who was sent to Japan by his employers during 1877 on a plant-hunting expedition. Thank you very much, Mr. Maries and the Veitch Nurseries!
Hydrangea macrophylla is a deciduous shrub … meaning that it sheds its leaves during the winter … growing to 2 metres tall … say, 7 feet in old money … and spreading to something in the order of 2½ metres …about 8 feet. Its carries large flowers which can be blue, red, pink, light fuchsia in colour, or dark purple. The colour of the flowers is determined by soil pH … and here we get very technical … pH being “a numeric scale used to specify the acidity or alkalinity of an aqueous solution. It is the negative of the logarithm to base 10 of the activity of the hydrogen ion. Solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are alkaline or basic.” The quote comes from Wikipedia. Acidic soil with a pH value of less than 7 will normally result in flower colours tending towards the blues, while an alkaline soil with a pH value greater than 7 will produce flowers which tend towards a pink colour. The explanation is that the flower pigments are affected by the presence of aluminium ions in the soil; and, while the enthusiastic gardener can try to change the colour of pink flowers by using one of the hydrangea blueing compounds which are available from garden centres, discovering the pH level of the soil prior to choosing a cultivar well suited to the conditions is strongly recommended. I might add that there are cultivars which produce white flowers regardless of the pH level of the ground. Again, in areas where the tap water is what is called ‘hard’, meaning that it has a high mineral content … not the case in most of central Scotland … it is best to use rain water if blue-flowering varieties need to be watered during the summer months.
Sadly, the wonderfully bright blue flowers of the hydrangea just a few metres from where I am seated have now faded to a tired grey: but in my mind’s eye I can still see yesterday’s blues; and I can hope that these will reappear come next summer.