Well, here we are already in the last month of the summer which I know some gardeners feel is a difficult month with often parched and brown lawns, prolific weed growth and the early summer flowering plants past their best. However, as I have tried to show over several August blogs and talks there are lots of excellent plants which will provide plenty of late summer interest and colour.
Many of these are covered starting in the 2020 blog in which I wrote about keeping summer bedding plants looking good for as long as possible as well as late flowering perennials such as Phlox, Penstemon, Japanese Anemones, Helianthus, Eryngium and Lavender and shrubs such as Buddleja and Hydrangea. In 2021 the blog came from Aberglasney where there are always lots of wonderful plants,ideas and inspiration to be discovered. In 2022 I wrote in some detail about Buddleja, Hydrangea, Echinacea, Erodium and Helenium. In 2023 I was ‘Preparing for Spring Colour’ which, of course, include spring bulbs, ground cover perennials such as Forget-me-not, early flowering perennials such as Doronicum, Dicentra and Euphorbia, spring flowering shrubs such as Daphne, Corylopsis and Cytissus, early flowering climbers such as Clematis and Honeysuckle and a great spring flowering tree, Amelanchier, the ‘Snowy Mespilus’. Finally, in August 2024 in ‘Feeling Good about Gardening’ I highlighted the lovely Dahlia, Hydrangea, Buddleja, Japanese Anemone and Betony (Stachys officinalis) a less well-known plant but one much loved by bees and butterflies. Also, as the title suggests this blog contained a short section on how and why gardening is good for us both mentally and physically and there were also sections on taking soft wood cuttings, collecting seed, summer pruning and planting autumn flowering bulbs.
For this month’s ‘Plant of the Month’ I have taken inspiration from an article in the July edition of the RHS magazine ‘The Garden’ by Andrew Ward from Norwell Nurseries in Nottinghamshire in which he sang the praises of Astrantias- the tough but pretty perennials which bring a beautiful intricacy to our beds and borders and even grow in heavy clay. In his nursery they grow well in a frost pocket on heavy, brick-making clay and regularly endure winter temperatures down to -10 Celsius. They are also long-lived plants that shrug off insect and mollusc attack, are rabbit resistant and flower prolifically in late spring and summer and then often again in the autumn. In general, those with the silver-green flowers are the easiest to grow in the shadier parts of the garden whereas in the sunnier spots the more dramatic reds, burgundies and mahoganies perform better.
The simple beauty of Astrantia major
Astrantias are members of the carrot or cow parsley family and, although completely unrelated to Asters, the genus name is derived from the Latin word ‘aster’, which means star and refers to the shape of the Astrantia’s floral bracts. It is these outer bracts (modified leaves at the base of a flower) which provide the substance to the blooms and help to entice many pollinating insects to visit the true flowers which are small and individually insignificant and held in the centre of the bracts. It is these true flowers which have led to the Astrantia’s common name- ‘Aunt Hattie’s Pincushion’. The bracts, flowers and flower stalks can be lime, silver, pink, red or burgundy with the bracts varying in size, spikiness and degree of veining.
In the wild Astrantias hail from moist, continental meadows in sun or part shade but in garden situations they are remarkably adaptable. In the Nottinghamshire nursery they are grown around the edge of a wildlife pool along with Candelabra primroses and Trollius in soil which is continuously damp but not waterlogged. In their borders they are grown in the moistest areas with snowdrops and pulmonarias for the spring and peonies and Phlox paniculata for the summer.
Our Astrantia major with a pink Japanese Anemone and Cotinus coggygria ‘Royal Purple’ in partial shade in an east facing border.
Although there are around 10 known species, gardeners mostly grow forms of Astrantia major. The well-known and beautiful Astrantia ‘Roma’ (one of the earliest and longest flowering with pink flowers and bracts) is a cross between A. major and A. maxima and has the colour of the latter but the vigour of the former. Other good varieties to look out for are A. ‘Hadspen Blood’ (pink and lime), A. major ‘Star of Magic’ (pink-red) and A. ‘Buckland’ (silvery-green bracts and light pink flowers, one of the earliest to bloom and with up to three flower flushes each year).
At the Norwell nursery they give their plants an early mulch of homemade compost, a sprinkle of granular fertiliser in April and on drier soil some water in dry periods. The plants are cut back hard after their initial flowering especially if stressed by drought to prevent seeding and to encourage re-flowering. Astantias are stunning work-horses in the garden, make long-lasting cut flowers and are very photogenic, making them ‘stars’ bur definitely not ‘prima donnas’!
A second article in the same magazine also sparked an interest in a topic which I have raised before but never covered in any detail. It concerns all the various scents which plants produce and our very personal responses to them. Tanya Moulding, a clinical aromatherapist, considered these in her article ‘The Science of Scent’ with the view to encouraging gardeners to enjoy their gardens at a whole new level.
There is little doubt that a botanical scent can be a very powerful force often so evocative that the experience brings back, hopefully, wonderful memories and is also able to shift moods in an instant. However, what is also truly fascinating is that no two people experience scent in exactly the same way making it an incredibly personal experience. As Tanya wrote ‘are you drawn to the heady, florals of sweet peas, the freshness of cut grass or the earthy aroma of rain-soaked soil (known as petrichor)? And on which side of the fence are you when it comes to the ‘Marmite’ scents some folk adore and others abhor, such as paper-whites, astilbe and day lilies?’
Tanya believes that it is time that we all renew our acquaintance with scent, to learn to be much more conscious of it and to train our noses to pick up the nuances of scent molecules particularly because as we age the sense of sight takes a higher priority and the sense of smell a lower one. She claims that the benefits of doing so are enormous and will allow gardeners to enjoy their gardens in a new way. The appreciation of scent has the power to improve our lives, our sense of well-being and help us gain a deeper appreciation of the plants around us. Also, armed with a greater awareness of scents we can even craft our outdoor spaces to please our individual scent preferences by choosing the most suitable plants.
The science behind our sense of smell is truly fascinating and I will attempt here to just give you a taste of it- if you will excuse the pun! Many plants produce volatile organic compounds from flowers, leaves, bark, seeds, stems and even roots which readily evaporate, dispersing scent molecules, of which there are many different types, into the air producing an infinite number of combinations some of which are pleasurable and some less so. These scent molecules travel swiftly up the nostrils to reach a small patch of tissue lining the roof of the nasal cavity which has around 350-400 scent receptors. These detect and identify the scent molecules and send electrical signals almost instantly along the olfactory nerve to the olfactory bulb which is a processing unit at the base of the brain. The response to this is very rapid for all of us but scientists have discovered that these smell receptors don’t work the same for all of us- there is likely to be at least a 30% difference between any two people. However, this is not the only twist to the story because the olfactory bulb is also linked directly to the limbic system- a complex part or the brain that includes the hippocampus where memories are stored and the amygdala which is involved with emotional responses such as the ‘fight or flight’ survival response. This is why certain smells can instantly trigger vivid memories and emotions. When we inhale an aroma which we find pleasant, the olfactory system signals the limbic system, triggering the release of dopamine, a neurotransmitter linked to pleasure which elevates our mood and induce physical relaxation. Conversely, the smells which we perceive as unpleasant serve as a warning signal and the brain may, as a result, release adrenaline increasing alertness or even disgust.
In the second part of the article Tanya went on to identify the five main plants scents- sweet/floral; aromatic; spicy/peppery; heavy/exotic and citrus which she encourages us all to experience as much as we can in order to decide which of them pleases our unique sense of smell.
The Sweet/floral family of scents captures the essence of a summer garden in full bloom and ranges from the honeycomb sweetness of Lathyrus odoratus (Sweet Pea), Lobularia maritima (Sweet Alyssum), the unabashed florals of Gardenia jasminoides, the damp, sweet scent of Syringa (Lilac), the sweet fragrance of Philadelphus (Mock Orange) and the soothing, honey scent of Clematis rehderiana.
The Aromatic family includes the pungent, warm herbals of moss, fern and the fresh pine-bitterness of woodlands, the piercing vigour of Rosmarinus officinalis (Rosemary) and the fresh hay warmth of Chamaemelum nobile (Chamomile).
For the Spicy/peppery group which bridges the garden and the kitchen we need to look to the sharp scent of Eruca versicaria subsp. sativa (Rocket), the delicious fragrance of Matthiola (Stocks), Viburnum carlesii and Dianthus plumarius.
As the name suggests the Heady/exotic fragrances transport us to other parts of the world from the powerful, fruity scent of Lilium (Lily), Nemesia ‘Wisley Vanilla’, the seductive musk scent of Iris germanica, Nicotiana sylvestris, the cocoa scent of Cosmos atrosanguineous and the coconut notes of Clematis ‘Lampton Park’.
Finally, we come to the Citrus group which extends well beyond the familiar fruity and tangy zest of Citrus limon (Lemon) or the frilly, lemon-scented foliage of Pelargonium crispum to the citrus notes in Philadelphus coronarius, the refined bergamot-orange of a torn Monarda didyma leaf, the leaves of Thymus pulegiodes ‘Archer’s Gold’ and the zesty scent of Nepeta cataria ‘Lemony’.
You will have noticed, no doubt, that the often strongly fragrant rose was not mentioned in any of the five groups. This is because plants in the Rosa genus produces more than 300 aromatic compounds and can actually feature in any of the five groups depending on the particular species or cultivars.
I have two other short items for you this month, the first of which being the ‘Hampton Hack’. This is along the lines of the better known ‘Chelsea Chop’ but instead of in May it is normally carried out around the time of the Hampton Court Palace Garden Festival in early July but it is not too late to do it in early August. As the name also suggests it is a more drastic method of pruning than just a ‘chop’. It refers to the cutting back of early flowering perennials which have usually become floppy and leggy by this point in the year right back to the ground after which the plants with the help of a good water will grow new, neater leaves and will have every chance of producing a second bloom of flowers later in the summer or into the autumn. It applies particularly to the larger of the hardy Geraniums and Alchemilla mollis which can both get out of hand and very untidy if left to their own devices.
Some of our hardy Geraniums, most of which have been cut back in the last few weeks
Finally, I thought that I would just mention a relatively new word which seems to be appearing much more frequently particularly on bags of potting compost. This is the material ‘Biochar’ which is now being added to many different types of compost and rightly so in my view. It is a highly stable, carbon-rich material with unique benefits for both soil and plants. It is formed through ‘pyrolysis’, a process where wood is heated in an oxygen-deprived environment similar to the age-old process of charcoal making. Rather than burning the wood transforms into a porous, honeycomb-structured material capable or retaining water and plant nutrients. By adding it to composts or directly to the soil it can provide a steady supply of nutrients, improve soil structure to enhance water retention and aeration, reduce the loss of nutrients though leaching and generally provide a sustainable and healthy environment for plant growth. I’m also delighted to say that its benefits go even beyond that as it can also help to mitigate climate change as it acts as a long-term carbon store, locking carbon into the soil for up to, and possibly beyond, 100 years! Basically, when added to compost the biochar offsets all the emissions of carbon dioxide from the production of the compost itself with all its other benefits still to come- so very much a ‘win-win’ situation.
That’s all for this month except for the free August talk at the Old Railway Line on Saturday the 2nd at 10am when Lucy, the plant area manager, will join me for a look at some great plants for our August gardens, discuss the topics mentioned in the blog and answer any general gardening questions on the day. I will be back in September with some more gardening thoughts and suggestions but until then enjoy the last month of summer in all its glory.
Keith.