The September Garden
My RHS book on ‘Gardening through the Year’ tells me that September is a wonderful month and I whole-heartedly agree. True the shortening of the days are a sign that the year is moving on but there is so much to admire and enjoy in the first month of the autumn. The harvest is in full swing and the first signs of the wonderful autumn colours to come are there for us to see. It is also a time, as we will explore in this month’s blog and talk, to think about the autumn and winter to come and to add some plants which will grace the garden as the seasons change.
Back in September 2020 my blog referred to some of my favourite September plants and to jobs for the month. September 2021 came from the gardens at Aberglasney and in September 2022 my ‘plants of the month’ were Japanese Anemones, Asters (Symphyotrichon), Rudbeckia and ornamental grasses and the blog also contained a section on spring bulbs. All these are still available on the Old Railway Line’s new website under ‘News and Blogs’, ‘show tags’ and ‘Monthly garden guides’.
Two lovely Japanese Anemones in our own garden
Aster x frikartii ‘Monch’ and Rudbeckia fulgida var. sullivantii ‘Goldsturm’
My main theme for this September’s blog and talk (on Saturday 2nd at 9-30am in the Tearoom) is ‘Plants for Autumn and Winter Interest’ which you will appreciate is quite a large topic for just one month. Fortunately I have written about this before and I will refer you to the relevant blogs for the full lists of plants in each section and will concentrate here on at least one of my favourite plants from each section.
Starting with Autumn I refer you to the October 2020 blog which contains details of lots of excellent autumn plants under the headings of ‘leaf colour’, ‘fruits’ and ‘flowers’. Leaf colour is probably what most people think of first when it comes to autumn plants. Deciduous trees, shrubs and climbers sense the shortening days and falling night time temperatures and as a result begin to move into their period of winter dormancy. Essentially this means that they begin the process of withdrawing valuable chemicals from their leaves and storing them within their permanent structures of branches, trunk and roots. In particular they remove both sugars and chlorophyll. The latter is the green pigment in the leaves and as it is withdrawn the other colour pigments which have been there all along become more visible and as a result the leaves begin to change colour. The reds and purples come from a mix of remaining sugars and Anthocyanins and the yellows and oranges from Carotenes and Xanthephylls. Trees being large and dominant in both gardens and the countryside in general obviously have the greatest impact during this ‘closing down’ period and there are lots of good ones to choose from including Acer, Amelanchier, Betula, Cercidiphyllum, Liquidamber, Parrotia, Prunus, Rhus and Sorbus. These are all my favourites really but I will pick out two which I haven’t highlighted before. The first is the very well named Liquidamber, a member of the Hamamelis family. It is a genus of just four trees from moist woodland in E. and SW. Asia, N. America and Mexico. Their maple-like leaves are dark green, palmate with 3-7 lobes turning rich reds and oranges in the autumn and they have the great advantage of staying on the trees longer than most of the other trees on the list. The species most commonly grown in this country is L. styraciflua, the Sweet Gum, which is a large tree when mature with 6”(15cm) leaves giving it quite an impact in any setting. It has several cultivars, the best of which in my opinion is L. styrac. ‘Worpplesdon’ which has deeply lobed leaves turning purple-red and then orange-yellow in the autumn.
Parrotia, another member of the Hamamelis family, is an even smaller genus with only one species of tree, Parrotia persica, from the forests of the Caucasus and N. Iran- hence its common name, Persian Ironwood. In addition to its striking autumn colour when the green leaves turn red and orange from the leaf edge inwards, as most of the Hamamelis family do, it also has peeling bark and in late winter and early spring on bare branches has tiny, spider-like red flowers.
Of course, autumn leaf colour can also come from a variety of deciduous shrubs, some of the best being Berberis, Cercis, Cotinus, Euonymus, Hamamelis, Hydrangea and some of the Viburnums. Berberis is more commonly grown for the colourful, yellow or orange spring and summer flowers but some species and cultivars also produce excellent autumn colours. Berberis thunbergii is certainly one species to look out for with its red-tinged, pale yellow flowers in spring followed by glossy red fruits. Many of its cultivars have interestingly coloured and marked leaves and some of them produce striking autumn colours. B. thun. atropurpurea has dark red-purple foliage which turns red in the autumn, ‘Dart’s Red Lady’ has very dark red-purple leaves which turn bright red in autumn and ‘Golden Ring’ has purple leaves narrowly margined with golden-yellow, turning red in autumn and also produces red fruits. Euonymus, the Spindle Tree, is another large genus which contains some very good deciduous shrubs for autumn colour. Probably the best of them is E. alatus, the Winged Spindle, which has brilliant dark red leaves in the autumn in addition to its interesting corky winged bark and reddish-purple fruits with 1-4 lobes and, inside, seeds with orange arils (seed coats). Euonymus alatus ‘Compactus’ is an excellent smaller form for those with less space. A similar cultivar is E. europaeus ‘Red Cascade’ with the red autumn colour and red and orange fruits but without the winged bark.
A Euonymus in the woodland garden at Aberglasney
Finally on the subject of autumn leaf colour I turn to the climbing plants. Probably the best known and widely grown is the Virginia Creeper, Parthenocissus, of which there are several species to choose from all giving wonderful autumn reds. P. quinquefolia with its 5-lobed leaves is one of the strongest growers and needs large walls or trees for support. P. tricuspidata, the Boston Ivy, with its 3-lobed leaves is also vigorous and needs similar support. A smaller species is P. thomsonii with its five, oval and sharply toothed leaflets which are reddish-purple when young, turning purple-green in the summer and bright red in autumn. Equally good autumn colours come from the Vitus genus, the Grape Vine. V. ‘Brandt’ produces 3-5 lobed, bright green leaves which turn bronze-red with green veins in autumn as well as large bunches of edible, blue-black grapes. V. coignetiae has large, heart-shaped, dark green leaves which are brown felted beneath turning bright red in the autumn. It also produces blue-black grapes but these are unfortunately not edible!
A striking Parthenocissus on the wall overlooking the lake at Aberglasney
This links us nicely into the autumn plants which produce colourful fruits and apart from the ones I have mentioned already there are many others to choose from including Callicarpa, Cotoneaster, Leycesteria, Mahonia, Pyracantha, Sambucus, Symphoricarpus and some Viburnums especially V. opulus. Of these perhaps Callicarpa bodinieri var. giraldii ‘Profusion’ is the most unusual with its small pale pink flowers in midsummer followed by spherical, bead-like, dark violet fruits in the autumn. It also has the additional attraction of bronze young leaves in the spring and is rightly referred to as the ‘Beauty Bush’.
The rather unusual berries of Callicarpa
On the subject of ‘Fruit’ in general most gardeners think of it as the sweet and fleshy crops borne on trees and shrubs through the summer and autumn. In terms of edible fruits these would include top fruit such as apples, soft fruit such as raspberries and bush fruit such as redcurrants. In terms of ornamental plants most gardeners would think of such things as crab apples, berries of all kinds and perhaps the more unusual fruits such as those formed on Fuchsias. To a botanist, however, all flowering plants are capable of producing fruit which is a strict term used to define the structure which matures from a flower upon fertilisation of its ovary. A fruit contains a seed or seed enclosed by the pericarp, a fleshy or hard coating that serves to protect the seed and aid its dispersal. Fruits fall into one of three groups- Simple, Aggregate and Multiple. Simple fruit can be ‘dry’ such as maple seeds, grains of cereal, pods of legumes and nuts or ‘fleshy’. This includes ‘berries’ where the entire ovary wall develops into a fleshy pericarp as in blackcurrants or ‘drupes’ where the inner part of the ovary wall develops into a hard shell, the pit or stone, and the outer part into a fleshy layer as in the Prunus genus. Aggregate fruits come from a single flower that has a number of separate carpels (female part of a flower) which fuse together as they grow. Separately these are known as ‘fruitlets’ and together they become aggregate fruit, examples of which are blackberries and raspberries. Strawberries are also aggregate fruits but are formed in another way when the ‘receptacle’ part of the flower (the tip of the stem from which the flower arises) becomes enlarged and fleshy as if it were part of the fruit. Pome fruits (apples, pears and quinces) are another example of an aggregate fruit formed in this way. Finally ‘multiple’ fruits are formed from a flower head or inflorescence (many small flowers on a single stem) when each flower produces a fruit which then fuse into a larger, single fruit. Fleshy examples include pineapple and mulberry and a dry example is that of the ‘balls’ produced by plane trees (Platanus).
For plants producing autumn leaf colour and fruits their growing season is clearly coming to a close but there are many flowering plants, mainly herbaceous perennials, for which autumn is their main season. These include Aconitum (Monkshood), Japanese Anemone, Aster (Symphyotrichon), Ceratostigma, Cyclamen hederifolium, Colchicum, Fuchsia, Helianthus, Rudbeckia, Schizostylus, Sedum and Tricyrtis (Toad Lily). Many of these I have highlighted before in various blogs and talks so here I will just pick out two of the less well-known ones. Schizostylus, the Kaffir Lily, is a genus of just one species of rhizomatous perennial from damp meadows and stream banks in S. Africa. It is grown for its showy, gladiolus-like spikes of open, cup-shaped flowers produced from late summer to early winter and its sword-like leaves. S. coccinea has several cultivars including S. cocc. ‘Major’with large red flowers, ‘Viscountess Byng’ with pink flowers and ‘Sunrise’ with salmon-pink flowers.
Schizostylus coccinea ‘Major’
Ceraostigma is a genus of 8 deciduous and evergreen subshrubs and herbaceous perennials found in dry, open situations in N. E. Africa, the Himalayas, China and S. E. Asia. They are grown for their 5-lobed blue flowers from late summer to autumn. The two most commonly available species are C. plumbaginoides and C. willmottianum which are both fairly compact growers suitable for the front of beds and borders in sunny spots.
That completes the section on good plants for the autumn and I can now move on to some winter plants which will help you to get through the winter months by having something of interest to catch the eye even if it is through a window from the comfort of indoors! There is lots of detail on the plants mentioned in this section in the second half of the November 2020 blog on the website. As with autumn there is much more than just flowers to provide this interest although I will start with them. There may be only a small number of winter flowering plants but they can make a big impact in any garden and are therefore well worth looking out for. One tree which reliably flowers in winter, certainly during milder spells, is Prunus x subhirtella and as such it is generally known as the winter flowering cherry. This is a deciduous, spreading tree with small, 3-lobed, sharply toothed, dark green leaves, pale bronze when young, turning yellow in the autumn. Bowl-shaped white or pink flowers are borne in clusters intermittently from autumn to spring often on bare stems and are followed sometimes by cherry-like, red, later black fruits. P. x sub. ‘Autumnalis’ has semi-double, pink-tinged white flowers, ‘Autumnalis Rosea’ is similar but with pink flowers and ‘Pendula Rosea’ has weeping branches and rose-pink flowers.
Unlike with the trees there is a much wider range of winter flowering shrubs. Their flowers might be small but they really stand out in the winter garden as most are white or yellow and are produced before the leaves. Most are also fragrant in order to attract the few pollinators which are about during the winter. My favourites include Chimonanthus, Cornus mas, Daphne, Erica carnea and darleyensis, Garrya elliptica, Hamamelis, Lonicera, Mahonia, Sarcococca, Skimmia, Stachyurus, and Viburnum x bodnantense and tinus. I have written about most of these several times before but will pick out one here which most people would probably not consider as a winter flower. This is Lonicera, Honeysuckle, which we generally associate with the summer months. However, there are two excellent winter flowering species which are well worth growing if you have the space. The first is L. fragrantissima which has tubular, 2-lipped, very fragrant, creamy-white flowers in winter and early spring. For maximum flower it is best grown on a south or west facing wall. The second is L. x purpusii ‘Winter Beauty’ which is a more rounded shrub with red-purple shoots and again tubular, 2-lipped, very fragrant white flowers with conspicuous yellow anthers.
In addition to these shrubs there are also two winter flowering climbers which are worth a mention, Clematis cirrhosa and Jasminium nudiflorum. The latter with its bright yellow flowers on bare but still greenish stems is not strictly a climber but is easily trained against a wall or fence.
Finally on the topic of winter flowering plants we must include Helleborus niger, the Christmas Rose, which produces cheerful, white, sometimes strongly pink-flushed blooms with greenish-white centres. H. niger ‘Potter’s Wheel’ has particularly large, bowl-shaped white flowers with green eyes. There are also, of course, some early flowering bulbous plants which appear as if by magic in late winter and early spring. These include the Winter Aconite, Eranthis hyemale, which often appears poking through snow or a frosted ground surface, Cyclamen coum which flowers after Christmas together with its patterned, heart-shaped leaves and the wonderful Snowdrop, Galanthus, which never fails to brighten up any winter garden.
As I hinted earlier though there is much more to ‘good’ winter plants than just flowers. I am thinking here about other attractions such as ‘bark and stems,’ ‘fruits’ and ‘shape and form’. It is in the winter when deciduous trees and shrubs are devoid of their leaves that the colours and textures of bark and stems can be best appreciated. Some trees immediately come to mind, Acer griseum (Paper bark) and pensylvanicum (Snake bark), Arbutus unedo (Strawberry tree), Betula utilis var, jaquemontii (Himalayan birch) and Prunus serrula (Tibetan cherry). In particular I like Acer griseum which, although it can get to 30ft (10m) high, is in my experience slow growing and therefore suitable for many garden situations. It has peeling, orange-brown bark but also 3-palmate leaves which turn red and scarlet in the autumn. In spring it also has small yellow flowers in pendant racemes (clusters) making it a tree with more than just one season of interest. In terms of shrubs with attractive bark or stems it is the winter stem dogwoods, Cornus, which come immediately to mind. The species Cornus alba, the Red-barked dogwood, has as its name suggests red winter stems but some of its cultivars have this as well as other attractions. C. alba ‘Aurea’ has yellow leaves, C. alba ‘Elegantissima’ has grey-green leaves with white margins, C. alba ‘Kesselringii’ has blackish-purple winter stems and red-purple autumn leaves, C. alba ‘Sibirica’ has bright red winter shoots and red autumn leaves while C. alba ‘Spaethii’ has broadly yellow-margined leaves. A second species is, C. stolonifera, which also has red winter stems but one of its cultivars, C. stolon. ‘Flaviramea’ has bright yellow-green winter shoots. Another good one to look out for is C. ‘Midwinter Beauty’ which has a mixture of red, yellow and orange stems.
A young Acer griseum beginning to show some bark colour and Cornus ‘Midwinter Beauty’
In terms of winter fruits I think we need to look towards Holly (Ilex) and Pyracantha. As I have mentioned before male and female holly flowers are usually borne on separate plants and both are therefore needed to produce fruits. This means that we gardeners have to either look for self-fertile plants which have both male and female flowers such as Ilex aquifolium ‘J. C. van Tol’ or have both a male and female holly in the garden. Plant labels should say if the plant is male or female but another good guide is the presence of berries which means that it is either self-fertile or female. Pyracantha, Firethorn, is in my opinion an under-rated plant. People are put off, I think, by their large and very sharp thorns which can make any pruning or training a painful experience. However, it also means that these shrubs can form an almost impenetrable barrier if this is desired along a garden boundary. Another great attraction is that the fruits come in a variety of colours from red, through orange to yellow.
Finally I come to ‘shape and form’ which we have talked about many times in terms of garden design. This is a particularly important aspect of the winter garden when the eye is not distracted by an over-abundance of leaves and flowers. Evergreen plants play a very important role here for, as well as providing an all-important ‘green’ background, their various shapes can be fully appreciated and without them the winter garden would be a much poorer place. Just imagine all the different shapes and forms as well as sizes and colours that the following can bring to the garden in winter- Artemesia, Bergenia, Buxus, conifers in general, Cordyline, Erica, Euonymus, Hedera, Ilex, Phormium, Pyracantha, Taxus and Vinca. Deciduous plants bring a distinctly different ‘shape and form’ interest to the winter garden when they can be viewed without their leaves. The intricate structures of trunk, stems, branches and twigs can be seen in all their glory if we gardeners just take the time to look rather than just see them as a bare plant. Of course, if the twigs or smaller branches are twisted or contorted in some way their forms are even more interesting. This is where plants such as Corylus avellana ‘Contorta’ (Corkscrew Hazel), Salix matsudana ‘Tortuosa’ (Twisted Willow) and one of my favourite cherries, Prunus incisa ‘Kojo-no-mai’, really come into their own.
I hope that some of the above will help you to choose some new plants for your garden that will enable you to get more out of it in both autumn and winter.
This month’s RHS main ‘bee friendly’ recommendation is Salvia, in particular Salvia ‘Amistad’ with its purple, velvety flowers which produce food for bees from summer until the first frosts of the autumn. It requires a position in full sun, a bit of shelter from strong winds and a well-drained soil. Its long, tubular flowers are particularly good for the longer-tongued bumble bees but the shorter-tongued ones can also access the flowers by biting holes in their sides in order to reach the nectar inside! Unfortunately S. ‘Amistad’ is one of the more tender Salvias and, in the ground, may not survive the welsh winter. However, there are many other Salvias which do and still provide plenty of food for our bees. Other plants on the September list are Buddleja, Verbena bonariensis, single-flowered Dahlias and Ceratostigma which I mentioned earlier.
That’s all for this month but I will be back in October for another blog and the final talk of the year. The winter months ahead offer gardeners an opportunity to look at the structure of their gardens in terms of both the soft landscape (natural) and hard landscape (man-made) and this will be the main topic for October. However, as always there will also be sections on ‘Plants of the Month’, ‘Bee friendly’ plants and anything else which has caught my interest! The talk will be on October 7th at 9-30am in the Tearoom and I hope to see you there. Until then keep well and enjoy the beginning of autumn.