Many years ago, when I had dark hair and fewer fillings, I became aware of a rather different hydrangea that I was desperate to grow. It sounded really showy, and the fact that it was supposed to be less than reliably hardy made it doubly desirable to me. I have become a little more sensible in my plant choices, sometimes, but I have still wanted to get to know H. involucrata personally. Patience has its rewards and now I have it.
I must admit that the plant may be a slight anticlimax if you are expecting something really flashy – this has a more subtle charm and could be thought of as interesting rather than colourful. The defining feature is, as the name might suggest, pairs of rounded, shell-like bracts that enclose the flowers in bud. I failed with the camera and my photos of the buds are not fit to be been. But, as might be expected, the buds look rather like those of Salvia involucrata, but in a much, much paler pink. In fact they remind me of a very mundane and rather pathetic Medinilla magnifica.
When I first heard about it, most references said that it was almost herbaceous in habit because of the lack of hardiness. The good news was that it flowered, in late summer, on the new growth, so even if it was cut to the ground by frost or an overenthusiastic gardener, it would still bloom. And unlike the usual ‘hortensias’ the foliage is coarsely hairy, rather like H. aspera and its clan. But this is a much smaller plant, often wider than tall, usually topping out at 1m. The bud scales drop off as the flowers start to open and they are the regular ‘lacecap’ affair with the large, sterile flowers in pale pink around blueish fertile florets in the centre. There is a double form called ‘Hortensis’ which was what I coveted most, but the plant I have is ‘Tokado Yama’ which seems to be a fairly common cv. with pale pink sterile florets with a slight yellow tinge at the base. I suspect it is a hardier selection than ‘Hortensis’.
The species is native to Japan and Taiwan (Formosa) – ‘Hortensis’ was introduced to the UK in 1906. It is useful for the late season of the flowers, which should look clean and fresh in September and October. It is traditionally recommended for planting at the base of a sheltered wall but it needs a little shade and moist soil so be careful against hot sunny walls. It is too early for me to rate it yet but I like it so far.