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A (mostly) unremarkable British summer, so far…

July 29, 2019
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It was a typical July here with alternating warm days scattered among a lot of damp and dismal ones, sometimes worse than that. But then on Thursday 25 we, like most other parts of Britain, had one of the hottest days ever recorded – maybe the hottest. It certainly reached 31°C (87°F) here on the N. Wales coast but mercifully there was a fairly brisk breeze and I was happy to potter in the garden for much of the day.

It also happened to be the first day of Boris Johnson’s new government…. the soothsayers of old might have had something to say about that, but that’s enough (probably too much) of politics, and I promise not to stray away from the horticultural straight and narrow again!

By the middle of July this garden is always past its best and one mostly has to look to individual plants, or serendipitous combinations, to carry the diary forward, rather than wondering what to omit, which is generally your diarist’s happy condition from March to the end of June.

A few more campanulas

Campanulas are, of course, along with saxifrages, dianthus, gentians and primulas, one of the backbone genera of the rock garden, being particularly important towards the end of the season. For most of us, the bellflower with its simple symmetrical form in generally muted shades of  blue or pale pink, often white, is satisfying. The appeal is enhanced by the fact that the flowers are borne very freely, often but a short height above the mat of foliage, sometimes on a robust erect or pendulous flower stalk. They are also generally produced over quite a prolonged period.

In my June entry I discussed several of the earliest to flower, now I would like to bring five more of the best to your attention, although, of course, many of you will already know and grow them. They are, in the order illustrated below, C. calaminthifolia, C. cochlearifolia ‘Elizabeth Oliver’, C. x wockii ‘Puck’,  C. alliarifolia ‘Minor’, C. raineri. The first four are very easy and generally long-lived in any sunny, well-drained spot, preferably in rather poor soil as otherwise the flowers may become engulfed in foliage. Like many mat-forming plants, C. calaminthifolia and C. cochlearifolia (of which there are many good forms from dark blue through paler shades to white) move gradually outwards by growing mainly at the perimeter, sometimes becoming less floriferous in the centre. Top dressing with fine gritty compost in spring as the mats start into growth  can help alleviate this problem and such species are, of course, easy to propagate from already rooted pieces from the margins.

Campanula raineri is also stoloniferous, although in nature generally limited to rock crevices or coarse limestone scree, but whether in the glorious sky blue type form shown here, or the crystalline albino, is much more restrained and may easily be lost, so make sure to propagate it while you have material available. All campanulas (excluding doubles such as ‘Elizabeth Oliver’ that set no seed) can be raised from seed, which is generally dust fine and best sown very thinly on the surface of chippings above the usual well drained compost. Careful watering with a fine rose on the can will suffice to settle the seeds between the interstices of the gravel or rain will do the same job. However finely the seed is sown you are likely to get clumps of tiny seedlings in due course. Rather than try to pot these individually, I generally prick them out in little batches, thinning them out later if need be.

Codonopsis ovata?

I have grown quite a few of these campanula relatives over the years, often under dubious names, for the taxonomy at least of plants in cultivation is confused to say the least, and they all, whether climbers such as C. clematideaC. vinciflora, or slightly untidy perennials, including the plant shown here, appeal to me. This is chiefly because the insides of the flowers, which are generally very pale blue or white, are especially intricately marked. But this generally requires you to turn them up to look as they hang down from the wiry stems; many good things require a bit of effort for utmost enjoyment.

They hail from Asia, often in woodland or other shady to semi-shady conditions, various representatives being found throughout the Himalaya east to Japan. Being tuberous rooted perennials which completely disappear from view for 10 months of the year, their position requires marking, but they will happily grow up and through other plants that impinge on their space. The foliage has an unfortunate foxy smell when brushed against. The best way to propagate them is from seed as described above for campanulas, but it may be possible to remove bits of tuber in the spring or autumn from old, well-established plants.

Old faithfuls

Some plants, including the codonopsis just referred to, grow and flower without any trouble every year. Because of this, it is easy to overlook them when their appointed time to perform arrives but this is a mistake, for while we all like to succeed with tricky plants, and perhaps even occasionally to show off to our gardening friends, it is these old faithfuls that really make the garden what it is. Whether it be carpets of thyme in various colours, ever-expanding clumps of good alpine perennials, such as Patrinia triloba, or big old plants of such glories as the so-called ‘pink dandelion’ (Crepis incana) or shrubby Crassula sarcocaulis, they provide the enduring backdrop for the performance of more fleeting and fickle beauties.

Two late-flowering daphnes

Now that it is well established in cultivation Daphne x transatlantica ‘Eternal Fragrance’ is one of the best loved of its illustrious tribe, mainly because it is easy to grow and flowers more or less continuously from spring to autumn. Raised by Robin White, the doyen of British daphne breeders, and released in 2004, it is a hybrid between D. caucasica x D. collina. It grows quite fast and will easily make a rounded bush 1m x 1m within 10 years.

The small plant shown is a four year old cutting. Another advantage of this cultivar is that it is easily rooted – the best time for taking cuttings is July-August in the UK when the new wood is beginning to harden. Cuttings will root without any special treatment. I generally use a Perlite and composted forest bark rooting medium in about equal amounts. It is important not to overwater the compost, which in my case is contained in a plastic seed tray with perspex lid, shaded by draped plastic netting that reduces light transmission by 50%.

Daphne jasminea, the second daphne shown here, is quite different: slow growing, temperamental and difficult in my experience to root from cuttings (and not free with setting seed either). In six years this plant, which is of an upright form less frequently seen than those of a more prostrate demeanour, has only grown to c.25 cm high x 20cm wide, and it is only really this year that it has flowered freely for the first time. The flowers make very little impact at a distance and unlike those of the eponymously named ‘Eternal Fragrance’  are unscented, at least to my nose. As you can see, they do repay closer inspection, but this is not a ‘wow’ plant by any means.

Rhododendron decorum subsp. diaprepesauriculatum  ‘Polar Bear’

Most of the rhododendrons are long past flowering but this old (1950) hybrid inherits the late flowering habit of its pollen parent, R, auriculatum. My plant is c.25 years old and has reached 3m high and wide growing in quite dense shade that has increased over the years as companion plants have also expanded. The pure white flowers (no green throat to speak of in my plant) are slightly scented but they are chiefly useful for brightening up a darkish corner of the garden.

A serendipitous combination

Eryngiums seed around quite freely here and are mostly very welcome. Occasionally, they appear where they are not wanted but sometimes, as in the case illustrated here, they make good combinations with other plants. Here a seedling from Eryngium ‘Picos Blue’ has insinuated itself among the glaucous foliage of Zenobia pulverulenta ‘Misty Blue’. I hope you like it as much as I do.

Image of John Good John Good

John Good is a retired research forest ecologist with a lifelong interest in all aspects of the observation and cultivation of plants, alpines and woodlanders being of particular appeal. He has lived in North Wales for more than 40 years and he and his wife, Pam, have lived in their current hillside home and garden overlooking the sea for 27. He is an Emeritus Professor of Environmental Forestry at Bangor University and maintains a strong interest in all matters related to land use in general and the balance between agriculture and forestry in particular.

He has been a member of the AGS for more than 50 years and a judge at our shows for half of these, as well as being a member (now friend) of the RHS’ Joint Rock Garden Plant Committee. He has travelled and lectured widely on alpines and written many articles and several books on the subject, the latter leading to his having served as AGS Director of Publications and Assistant Editor of our journal. He has also always been heavily involved in his local North Wales Group.