Kent Alpine Gardener's Diary
This entry: 27 July 2017 by Tim Ingram
A walk through spring into summer...
A walk through spring into summer...
(Oak trees at Bewl Water)
In the south-east of England - and many other places as well - the last twelve months have been amongst the driest on meteorological record (see the figure on the Rainfall Map 2 in the Environment Agency monthly water situation report for the South East here: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/626192/Water_situation_report_Kent_and_South_London_June_2017.pdf - our rainfall over that period has been 60% of historic average). Until some welcome thunderstorms this July we had had only an average of an inch or so of rain each month since the turn of the year, and the soil water deficit that normally becomes most extreme by late summer was equalled in late May. March right through to early May saw little more than 15mm of rain in total, and a walk at Bewl Water in early July showed the reservoir at a very low level when at times it can lap the trees around its perimeter.
The soil here is very sandy and the picture above shows a rim of ox-eye daisies running around the reservoir which will be inundated at high level. Just at the point where the photo was taken is a discrete change to a mix of silverweed, Centaurium and Lotus which may delineate the more normal levels of water in the winter and spring.
Drought has always been a limiting factor on growing plants in our south-east garden in N. Kent, which I have often referred to before in these Diary entries. So far as alpines are concerned we tend to grow those from drier mountain ranges and situations. Years like this one test the garden and gardener more than most and define the projects to take forward into the future. This year, until the recent summer rains, has recalled the late-summer of 1990 when we had hosepipe bans in south east England and the garden was at its driest that I ever remember.
In a summer-dry climate as ours a Mediterranean-theme is an obvious way to think about the garden and from the very beginning the plantings have been inspired by Beth Chatto's even drier garden in Essex. Many alpine plants are tolerant of these conditions, in part simply because they are small plants that do not have the transpirational needs of larger perennials and woody plants, and are adapted to more extreme fluctuations of climate. The picture I showed previously of the Rock Garden bank in Faversham shows how these plants can be valuable in urban plantings surrounded by buildings and paving. (The much wider relevance of alpine plants, amongst others, for our urban environments as much as our gardens is being addressed by the Conference organised in Sweden this September by Peter Korn and his colleagues, where individuals such as Nigel Dunnett, James Hitchmough, Thomas Rainer and Panayoti Kelaidis are speaking on their experiences of landscaping: https://klintaconference.se). In our personal garden we are steadily using many small dryland shrubs and alpines to replant and provide stock for propagation in the future.
Since the first picture was taken we have cut down the large shrub of Photinia 'Red Robin' to provide a much bigger area for more choice and unusual species. At the same time that I took those photos in early April though, other parts of the garden are full of flower and interest from woodland perennials and early flowering trees and shrubs such as this Magnolia 'Susan'.
By summer the garden can become quite overgrown and weedy and we especially concentrate on winter and spring when opening for the National Gardens Scheme - notably under these rows of dwarf fruit trees, here viewed from above when pruning a large cedar overlooking them.
From ground level the diversity of plants becomes a lot more apparant.
Woodland plants are undoubtedly as strong a feature of the Alpine Garden Society as are true alpines (one of those perennial items for debate about the very name of the Society), and are certainly more familiar to most British gardeners and more adapted to our relatively equable climate. More than this they are naturally well adapted to the relative drought and shade of the woodland floor in summer so suit our particular garden well. And the tapestry of foliage and flower that they can give in spring is to my eyes the loveliest of all things to garden for.
Just like alpines they seize the opportunity to grow and flower when conditions allow early in the growing season and both are jewels in the spring garden. As spring moves on and the leaves begin to expand on the trees, bulbs in the lawn and meadow add to the scene from our kitchen window, and this has become one of the most fascinating parts of the garden as we add to their diversity and try to make the plantings more natural and easy to manage. This a picture taken on an NGS day when the lawn has been mown and edges cut and the sun shone!
At this time the more woodland areas, which dry out considerably later in summer and are heavily shaded, become overrun with Smyrnium perfoliatum (and Arum italicum!) as this picture shows.
By summer all these plants have died and are setting seed and we are making concerted efforts to curb their spread into more choice plantings by preventing excessive self-seeding. But what this picture does show is how, in a large and maturing garden, a more natural ecology comes to prevail, and this plant is always commented on by visitors who admire it and say they haven't been able to establish it in their own gardens!! Later growing plants such as ferns and many perennials can happily co-exist with Smyrnium, and the garden begins to teach a lot about the natural progression of plants and quite discrete changes in vegetation throughout the seasons.
(... to be continued)
By high summer this part of the garden is heavily shaded, more like a woodland glade, and the idea is to steadily introduce more ferns (especially species of Polystichum and Dryopteris) and perennials that are adapted to low light and dry soils. The trees here, Ginkgo biloba on the left and Cedrus deodara on the right, were planted nearly 40 years ago (a little too closely in hindsight) and opening up the canopy beneath them has created a wonderfully cool environment in the height of summer, and really accentuates the value of mature trees in the garden - let alone the wider landscape - when you are lucky enough to have the space to plant them.
In April and May when the woodland garden is really building pace, so many smaller shrubs and alpines also make an impression in the garden (and this is a time of year when the Alpine Garden Society Shows are horticulturally pre-eminent, before the burgeoning growth of early summer when Chelsea and much larger events steal the scene). These two daphnes, a super form of D. tangutica/retusa and the yellow D. gemmata, are strikingly different and show why this genus has such appeal for the plantsman. Both came originally from members of our small AGS Group in Kent - not a bad reason to consider joining a specialist plant society!
Under the apple trees at this is the time of Paeonia mlokosewitschii, coinciding with the fruit blossom, and which is just maturing seed as I write.
And the true excitement of a garden - we had the first flower on P. wittmanniana grown from seed. Looking back I wish I had invested in more peony seed from Jim Archibald, and this is a genus for us to grow more of in the future, as much for the foliage as flowers of different species and hybrids running on into summer.
One of the great growers of peonies in the UK is Billy Carruthers of 'Binny Plants' in Scotland and it's a sign of the value of the AGS Shows that he brought plants to the Early Spring Show at Harlow this year; here speaking with Bob Brown (Cotswald Garden Flowers), another rather stimulating UK nurseryman who grows plants for the adventurous gardener. Both also often come to the Plant Fairs organised by Fergus Garrett at Great Dixter and it's hard not to draw parallels between the value of the AGS Shows and such special plant events in enriching British gardens.
Some epimediums are also making more of an impression under the apples and are more resilient to drought than I had imagined, even if slow to establish and spread. This one, Epimedium 'Pink Champagne', bred by Darrel Probst is especially good, and the genus as a whole provides unique contrast with other woodland perennials.
Under a mature magnolia near to the house (planted probably just after the property was built in the 1970's) is one of the longest plantings we have made with groundcover of species such as Lily of the Valley, lamium and the epimedium relative vancouveria - a part of the garden which now looks after itself with little input from the gardener (in other words something to learn from!). A few years ago we introduced this curious plant of ancient lineage into the mix, Chloranthus sessiliflorus/fortunei, which is pollinated by thrips (https://www.researchgate.net/publication/31373588_Pollination_Ecology_ofChloranthus_serratus_Thunb_Roem_et_Schult_andCh_fortunei_A_Gray_Solms-LaubChloranthaceae). This looks to be setting some seed now and would be good to propagate. In habit, just like a trillium, it makes a compact clump that grows perfectly through woodland groundcover. This picture, again, was taken in spring.
Amongst true alpines in the garden the mountain stock, Matthiola scapifera (?), was exquisite on a raised bed in April. Lamium orvala below has seeded along the base of the sleepers edging the bed and grows and flowers better here in full sun than anywhere else. The latter is a plant I can never forget seeing for the first time on a Chelsea display made by Beth Chatto in the 1980's, the most striking of all dead-nettles that you can grow in the garden.
Another real sun-lover, the Cretan endemic Linum arboreum (here in a pot) also grows well on a raised bed and flowers for weeks on end.
The sand/scree in our front garden has been a good success for a wide variety of alpines over time and this was a particular star flowering at the end of April, Pulsatilla vulgaris subsp. gotlandica. This is a plant we thought to have lost, originally grown from seed given to me by Richard Bird, and a diminutive and exquisite form of the common Pasque Flower. Unfortunately it only produced one flower and didn't set seed but will be watched closely next year in the hope that it can be propagated.
A bed like this needs a thorough 'spring clean' every few years if it is not to become too untidy and stale. So it has benefited from a rigorous weeding and top-dressing with coarse pea gravel, after the first flush of flowering early in the year.
One of the most exciting species to flower was the Turkish borage, Paracaryum racemosum, which also looks to have set a good crop of seed in the earlier hot and dry summer. It's growing here with a vivid blood-red dianthus (for which we have no name, unless someone can suggest one?), the two alpine daphnes, D. oleiodes and D. modesta, and the alpine fern Asplenium ceterach (which is a helpful indicator for when the bed needs watering). The 'soil' is pure sharp sand between 30-45cm in depth.
Tucked in next to this large block of tufa (one of those purchases from Ingwersens Nursery years ago when you wish you had bought more!), which is the perfect substrate in which to grow Helichrysum/Ozothamnus coralloides, the xerophytic fern Cheilanthes eatonii has overwintered successfully. A project that has long been on the back-burner is to make troughs for small alpine ferns growing amongst rocks, and one day that may happen?
Growing in the right setting quite common and easy alpines can excel and Silene uniflora 'Swan Lake' (which is a true 'ugly duckling' growing in a pot) consorted beautifully with Scilla peruviana in late May. It grows here in shallow soil on the edge of a hot gravel drive with (later to flower) the evening primrose Oenothera stricta 'Sulphurea' and Verbena bonariensis. Grateful thanks to Mike and Hazel Brett who initially gave us this plant; it's hard to convince gardeners of its worth when they just see it in a pot at a plant sale.
This is another very interesting plant that came from Mike and Hazel (and reminds me that I should at some point show pictures of their garden 'Old Orchard', at Loose in Maidstone, which was a revelation of how to garden with alpines): Stachys thunbergii a rare South African species from the Southern Cape which has been surprisingly hardy over the last couple of winters, richly coloured amongst the rock roses that I have shown in earlier entries.
Into July and Eryngium bourgatii becomes a strong feature, self-sowing in the front garden. Here it mixes with dieramas, the small Yucca harrimaniae and one of the later flowering small daphnes, and in the background the ever-flowering Euphorbia ceratocarpa.
On the sand bed campanulas and origanums come into their own, and one of the very best is Campanula x wockei 'Puck'.
The hot and dry summer has also suited Penstemon pinifolius 'Wisley Flame', a form selected by Alan Robinson which has stronger habit and glowing orange-red flowers. Many alpine penstemons are less reliable in the garden, very prone to fungal infection and die-back, but this is excellent and grows here in our normal well drained loam. This genus still excites though, and finding ways of growing some of the more fickle species would be a worthwhile challenge, along with so many other dryland alpines.
In summer the bulb bed in the middle of the lawn fills with various perennials; these pictures show Acanthus dioscoridis with sedums and Graham Stuart Thomas' good selection of Eryngium bourgatii in the background, and the rather beautiful and ethereal Mediterranean grass Oryzopsis milacea.
The white annual Erigeron annuus was a gift from Sue Bedwell's Oxfordshire garden (which I described in a previous Diary entry) and really is rather lovely. Like E. karvinskianus which seeds around so well in gardens and flowers for weeks on end, this will be spread to other places in the garden to naturalise.
Elsewhere in very sandy soil growing at the base of a Trachelospermum on the wall of the house the South African thistle Berkheya purpurea is striking. These flowers stand out in the late evening light of summer, along with the pervasive scent of the climbing shrub.
We've also grown Berkheya multijuga for many years, rather more brash for its yellow flowers (though not flowering this particular year). The plant behind though is probably the most unusual and fascinating of all I show - the Cretan umbelliferous chasmophyte, Athamanta macedonica. Perhaps last year's very hot and dry late-summer, and/or the climate this year, has stimulated flowering of the clump of foliage that has been growing here for many years? Sadly this plant is monocarpic and not one that will generate great interest from many gardeners, but for the botanically inclined, and umbellophile (we grow many unusual umbels), it is intriguing and hopefully will set plenty of seed.
Finally a scene taken after opening up a view through and beyond the trees in the background, in the slightly dishevelled state of the summer garden. Before long the meadow grass will be cut and removed and bulb catalogues perused to consider a few more species to add to the declining area of lawn! Out of view are plenty of weeds.