The Garden in June 2024 ‘Hot and Dry’
As June arrives and spring slips quietly away the glory of the early summer garden gathers pace. This is a month of roses and exuberant Clematis and beds and borders spilling over with the early flowering herbaceous perennials- Campanula, Delphinium, Dianthus, Iris and Oriental Poppies to name just a few.
With the longer days garden tasks are no longer onerous but more routine- dead heading of an evening, lawn mowing and edging, getting plant supports into place in anticipation of the growth to come, tying climbers into their supports and cutting spring perennials down to the ground after flowering so that they produce a neat mound of new foliage and later some bonus flowers.
Looking back over past blogs as I do each month, I see that in 2020 I was looking at some ‘good’ June plants here in our West Wales’ garden. June 2021 saw the first of twelve blogs from the wonderful garden at Aberglasney and in 2022 I was singing the praises of the fabulous rose. The Old Railway Line will be celebrating the rose in all its glory, as they do each year, in the week beginning Saturday 22nd June until Sunday 30th of June. On Sunday 23rd rose expert Gareth Davies will be in the garden centre to give one of his fascinating talks and on Saturday 29th I will be highlighting roses amongst other topics such as taking semi-ripe cuttings and planting autumn flowering bulbs as part of my ‘July’ talk which has been moved from July 6th to fit in with Rose Week. For further details have a look at ‘Events’ on the Old Railway Line website. In 2023 the blog concentrated on plants for late summer colour including herbaceous perennials, shrubs, climbers and ornamental grasses. With roses still in mind I will also refer you to the July 2023 blog which looked at some basic garden design principles and how the extremely versatile rose can be used in such designs.
Choosing my ‘five plants that I wouldn’t like to be without’ is becoming harder each month as the growing season really gets under way but looking around our garden I have come up with two herbaceous perennial plants, two shrubs and one small tree. The perennials are Centaurea, in particular C. montana which is often referred to as a cornflower when it is really a knapweed, and Valeriana officinalis, All Heal or Common Valerian. Centaurea montana has attractive lance-shaped, toothed, mid-green leaves which are woolly beneath as are the stems and striking, blue flowerheads with reddish-purple florets. There are now several cultivars available including C. alba (white), ‘Carnea’ (pink), ‘Parham’ (large, dark lavender-blue flowers) and ‘Violetta’ (dark violet). It flowers first in late May and into June but will flower again later in the summer if it is cut back hard after the first flowering. Valeriana officinalis is a tall (4-6 feet/1.2-2 m), upright, clump-forming perennial with aromatic, bright green, pinnate leaves and leaflets. Rounded cymes (inflorescences with many small flowers) of pink or white flowers are borne throughout the summer. We put one plant in a few years ago at the edge of the pond which has gently seeded around so that we now have at least half a dozen at various points in the garden. I must stress that this plant is not the Valerian which you see growing out of walls and gravel areas which seeds itself everywhere and which actually is Centranthus ruber or Red Valerian. Our original plant as I write has around 9 stems each of which carries flowers and flower buds not only at the tip but also from side shoots all along the stems.
Centaurea montana Valeriana officinalis
My two shrub choices for June are Weigela and Philadelphus. Weigelias are excellent shrubs for a mixed border with their showy, bell to funnel-shaped pink to red, sometimes white or yellow flowers. Our shrub is W. florida ‘Foliis Purpureis’ which has bronze-green foliage and dark pink flowers. I also particularly like W. florida ‘Variegata, which has pink flowers and white-margined, grey-green leaves. The Philadelphus or Mock Orange is a real June favourite with many gardeners due to its lovely, four-petalled, white flowers although some plants have double or semi-double flowers. P. ‘Virginal’ is a popular, vigorous, double and very fragrant choice for larger spaces whereas P. ‘Manteau d’Hermine’ produces equally good flowers on a much smaller, spreading shrub of around 3 feet/1 m high and wide. I especially like the simple, four-petalled flowers of P. ‘Sybille’ with its purple marks in the centre of each petal and P. ‘Lemoinei’ with its large, pure white flowers and yellow stamens. My tree for June is the flowering Dogwood, in particular Cornus kousa and C. florida. In late May and June these produce their small, yellow to green flowers surrounded by four, large bracts which start white and turn to pink as they age. In the autumn C. kousa also has strawberry-like, fleshy, red fruits and colourful leaves. Our plant is C. ‘Stellar Pink’ which as I write must have over a hundred beautiful flowers/bracts and is a real eye-catcher.
Weigela florida ‘Foliis Purpureis’ A Philadelphus at Aberglasney
Cornus ‘Stellar Pink’
For my main topic this month I am going to take a look at climate change and its impact on our gardens and the plants and creatures which live in them and, indeed, on the ways in which we may need to garden in the future. There may still be some discussion about the causes of such climate change but there is plenty of undeniable evidence that world climates are changing particularly over the last fifty years or so. Just in terms of plant flowering times there is good evidence from records in the UK going back as far as the 18th century that a rise in average temperatures of around 1.2 degrees Celsius has advanced flowering times, and therefore spring itself, by a full month. At first glance this might seem to be a good thing but if the other parts of the ecosystem such as bird and insect migration, nesting times and the emergence of insects don’t advance at the same pace then the ecosystem itself can be seriously disrupted. For example, pollinators may emerge to find that the blooms they rely on have come and gone already which in turn affects the birds that rely on those insects for food.
How can we gardeners react to such changes and perhaps even try to reduce their effects? On our own it seems impossible to make any difference but as a group we can have a huge and beneficial impact. Perhaps we firstly need to move away from just making our gardens look beautiful for our own eyes and begin to see our personal outside space as part of a much larger landscape and secondly, we need to create gardens that have the ability to thrive in ever changing conditions and to recover from adverse events predicted for the future ie. to be more resilient. This was certainly a key theme at this year’s Chelsea Flower Show which I’m sure many of you enjoyed the coverage of in late May.
It seems to me that in our part of the world we are faced with three major issues- a change to a more Mediterranean climate with hotter, drier summers and milder but wetter winters; more frequent and intense spells of extreme weather mainly in the form of periods of very heavy rainfall; a loss of biodiversity within our gardens as well as from the environment as a whole. The following are some practical ideas that may help to overcome or at least modify some of these issues.
Let’s start with the ‘hot, dry summer’ idea which we have been aware of for some time now. At the moment we are not experiencing the long, hot, dry summers of the Mediterranean lands but we are definitely more prone to spells of unusually hot and dry weather at different points in the summer, even in the usually cooler parts of the country. Many of our traditional ‘summer’ plants do not welcome such spells and suffer as a result. However, there are lots of other plants which thrive in such conditions or at least can successfully survive them. In order to make our gardens more resilient to such weather we need to make more use of such plants especially in the warmest, sunniest parts of our plots, in areas with thin, poor soils which struggle to retain moisture or on sunny banks and slopes where water drains away quickly. Many of such plants come from Mediterranean regions or from mountainous areas where soils are often thin and summers hot and dry. They all tend to have features which help them to reduce leaf temperature and/or transpiration ie. water loss from within the plant so that they can conserve the water they have. Such features include small, shiny leaves often with thick cuticles (the outer layer of the leaf), grey or silvery leaves and leaves with hairs or spines. As a real bonus many of these plants are also evergreen, have leaves and/or flowers which are scented and are herbs for either culinary or medicinal use. In terms of bulbous plants Allium and species Tulips eg. Tulipa tarda are good choices. In the perennial section there is a wider range to choose from including Achillea, Armeria, Artemesia, Dianthus, Erigeron, Eryngium, Erysimum, Euphorbia, some Geraniums, Sedum, Thyme and Verbascum. There are also a good number of shrubs which do well in hot, dry and sunny positions including Ceanothus, Cistus, Cytisus (Broom), Hebe, Hibiscus, Lavender, Parahebe, Rosemary and Sage.
Choosing the right plants is certainly a vital step in adapting parts of our gardens to hotter, drier spells in the summer but there are also some gardening techniques which we can use to help these plants perform at their best. Firstly, we have to remember that in our climate there are still large parts of the year which are not hot and sunny which these plants do not like so much! Our winters are particularly wet and may be getting even wetter and these ‘sun lovers’ can struggle in such conditions. The way to help them is to encourage excess water to drain away as quickly as possible by adding lots of grit or sand to the planting mixture and to plant them on slopes rather than at their bases. Secondly, there is a way in which we can help the soil to retain moisture in the hot, dry times by mulching the surface in order to reduce water loss by evaporation and in terms of these plants and the areas which they come from gravel or any form of stone seems to me to be the ideal choice.
However, even though there are ways of making the best use of the sunniest, driest and warmest parts of our gardens there are other parts where we will continue to want to grow our more traditional ‘British’ plants. In order to do so we need to make better use of our natural rainfall to help such plants get through difficult spells of weather- in other words we need to be wiser with water. The obvious way is to store as much as we can in times of plenty for use in times of shortage. For a start, after the initial cost of the containers, it is free and more importantly perhaps it is much better for your plants and soil micro-organisms than mains water with all its added chemicals especially chlorine. Even small roofs can collect surprisingly large amounts of water and with even just a few butts at different points in the garden watering can become a much easier experience as well as a vital one. Of course, with water becoming a much more valuable and scarce resource in drier spells it makes sense to use it wisely by only watering when necessary and in the most effective ways. Lawns, unless they are newly seeded or turfed, will survive even the driest spells and recover quickly when the rain returns. Also, a little water just splashed onto leaves and bare soil simply evaporates before it can be of any use to plants so watering is best done in the cooler times of the early morning or evening and needs to be directed at the base of the plant and its roots in a large enough quantity to get down to those roots. In really dry times it is also possible to make use of ‘grey’ water from the house after letting it cool and by avoiding pouring still soapy water over leaf surfaces. However, no matter how many water butts there are in the garden the largest amount of water storage capacity will be in the garden soil and there are ways of increasing this capacity and therefore the resilience of the garden to dry periods. The key is to increase the amount of organic matter in the soil by forking it in when preparing a new bed or border, adding it at planting time and by a layer to the surface annually. The latter has the added benefit of acting as a mulch which allows rainfall to penetrate but reduces evaporation from the soil surface and just below.
Other ways of conserving valuable water for plants in containers is to mulch the compost surface with such things as bark, gravel or shells and to use larger containers which can store more water and nutrients due to their large volumes of compost- we all know how quickly small containers can dry out! In beds and borders it is also possible to have some areas which don’t contain plants and therefore don’t require watering. Such spaces might have sculptures, driftwood or log piles for wildlife. Some gardeners are also beginning to use a method known as ‘chop and drop’ which is using any prunings directly where they come from rather than adding them to the compost bin, burning or recycling as green waste. The prunings are simply chopped up as small as possible and dropped into spaces between and under plants to act as an aerated layer of ‘greenery/brownery’, reducing evaporation from the surface and eventually adding organic matter to the soil.
Ironically, having dealt with the problem of a lack of water for our gardens we move onto a problem of, at times, too much water, either due to long periods of rainfall through the winter months or short, but very intense, periods of heavy rainfall in the warmer parts of the year. Most plants can survive a few days in waterlogged soil or even being under water but if there are areas of the garden which are prone to longer inundations such as the lowest part of the garden then it might be worth thinking about different ways of using them. One way is to create a pond which is allowed to rise and fall through the seasons acting as a natural reservoir by receiving excess water from higher parts and at the same time creating a thriving ecosystem in its own right. Such ponds work best when the sides are gently sloping and covered in pebbles and ‘marginal plants’ which can cope with the ebb and flow of water and at the same time cover and disguise any pond liner beneath. An alternative in lower parts of the garden would be to establish a bog garden in which a whole range of plants perhaps not suitable for other areas of the garden could be grown. Such plants rely on a constant supply of water and include perennials with large, colourful flowers as well as those with bold, even spectacular foliage and include Astilbe, Hosta, some Irises, Gunnera, Rogersia, Rheum, Candelabra Primulas, Ligularia, Lythrum and Mimulus.
This idea of creating new habitats to cope with climate change brings me neatly on to the third problem linked to climate change, as well as other ways in which we misuse our planet, which is the loss of biodiversity in the environment as a whole and in our gardens in particular. This is a subject which I have touched on before under the title ‘Gardening for Wildlife’ and that blog is still available from March 2021. In this month’s blog I include some more practical ideas on how we gardeners can help to make a difference which I found in an article from the Country Living magazine for September 2023 by garden designer Tom Massey. One very easy way of having more plants in our gardens to provide habitat, shelter and food for animals and invertebrates is to clothe vertical surfaces such as walls and fences with plants. At one end of the scale this could be simply planting one climber such as a Honeysuckle, Ivy or Jasmine on a wall or fence or at the other end of the scale creating a planting structure which can be packed with plants that are normally found in beds, borders or even the vegetable plot in the form of ‘green walls’. A similar idea is to cover horizontal or gently sloping surfaces with ‘green roofs’ which can beautify even the ugliest of structures such as garages, sheds, bin and log stores. They not only look good, they increase biodiversity, lock up carbon, insulate the spaces beneath and increase the life of the roof membranes. Tom Massey is also very keen on the idea which we considered earlier of getting the right plants into the right places and designing plant communities which can adapt to climatic conditions such as flood or drought and in turn support the creatures which depend on them. Garden design with wildlife in mind is so important these days as urbanisation continues and our countryside becomes less attractive for a whole range of native species of plants, animals and insects. I think that gardeners in general have now begun to realise that gardens are not just for us and that we need to garden and plant with wildlife in mind. In the March 2021 blog I looked at some easy ways of helping our wildlife- providing shelter and nest sites in terms of bird, bat and hedgehog boxes, bug hotels, log and stone piles; providing food for birds and hedgehogs (not bread and milk though!); planting native trees and hedging; covering walls and fences; planting nectar-rich flowers; creating a wildflower meadow or just setting aside the lawnmower in some grass areas; including water in some form ranging from a simple bird baths and water features to ponds themselves with all the benefits to wildlife which they bring. I covered pond building in two blogs from January and February 2021. Incorporating such items into our gardens will not only help wildlife to thrive but also help us all to reduce the use of chemicals in the garden which can be very harmful to many species. With more birds, hedgehogs, beneficial insects, frogs, toads and newts around nature will find a balance without the need for chemical intervention. Finally on this topic a display at the Malvern Spring Show in May really caught my eye and gave me great hope for the future. This was the stand of ‘Celtic Flowers’ (www.celticwildflowers.co.uk) who are based in Swansea and are part of the National Botanic Garden of Wales’ ‘Saving Pollinators Assurance Scheme’. They grow a wide variety of native wildflowers which are great both for pollinators and for birds, in peat-free compost of course, and have produced a leaflet with their five key ideas to boost the wildlife value of any project- create wildflower areas; build a pond; plant a hedge; add wildlife ‘furniture’ and if there is only room for one plant make sure it is Alder Buckthorn (Frangula alnus)! This is a new plant to me and is evidently a great all-rounder providing lovely alder-like foliage which is an important food source for several butterflies and moths, large numbers of small flowers which attract a whole range of pollinators including bumblebees, hoverflies and, at night, moths as well as berries produced through the summer and autumn which are an important food source for Blackcaps and Song Thrushes. Have a look at their website for further information.
One topic which I haven’t covered before came up in the ‘ideas for talks ‘from last October and that is the use of mirrors in the garden. My first thought is that having to look into a mirror every morning is quite enough for me and doesn’t need repeating in the garden! However, a more serious and sensible response would be that mirrors can be used in the garden very successfully in certain situations. They are mostly used in a wall or fence as a ‘window’ to give the impression that there is a part of the garden beyond the wall or fence. As such they need to be framed in some way as a window would be and positioned so that they can be viewed from one or both sides so that the reflection in them is of the planting on the opposite side. They don’t work when viewed straight on as the viewer is then part of the reflection and it becomes obvious that it is a mirror and not a window! One very clever way in which I have seen mirrors used successfully is as part of a ‘trompe l’oeil’ (a visual illusion in art). This is an arch in normal size with another but much smaller arch in the centre linked to the outer arch by trellis pieces angled to give the impression that what is a flat structure is actually three-dimensional ie that the smaller arch is in the distance behind the main arch. They are very effective on their own but with a mirror fitted into the smaller arch it appears that the trellis tunnel goes back even further and also gives glimpses of a garden beyond. It is possible to use ordinary mirrors but with safety in mind it is probably best to use those made from safety glass or for less expense and weight to use acrylic mirrors. These work really well but because they are not rigid it is important to fit them securely to a backing sheet so that they don’t distort the image- after all this is a garden, not a house of fun at the fairground!
Good use of a mirror in a covered area at a Gloucestershire garden centre I visited last month.
My final topic for this month is the pruning of deciduous shrubs which flower in the spring or early summer. Most of these shrubs produce flowers on last year’s growth and pruning at this time of year after flowering encourages new growth to form which will flower next year. Such shrubs include Forsythia, Deutzia, Philadelphus and Weigela. Without pruning these shrubs can become densely twiggy, top heavy, the quality and quantity of flower deteriorates and they expend a lot of energy in unnecessary seed production. The basic pruning method is to cut back all flowered shoots to a strong bud or pair of buds below and to remove any spindly growth. This encourages new shoots to grow in the coming months which will produce next year’s flowers. As plants mature (say after 3 or 4 years) a more dramatic method of pruning is also required in order to encourage strong, new growth from the base of the plant. Each year around one fifth of the main stems, choosing the oldest and thickest, need to be cut back to within 2-3”/5-8cm of the ground. Other shrubs which require the same pruning regime are Exochorda, Kolkwitzia (Beauty Bush), Ribes sanguineum and Spiraea x arguta (Bridal Wreath). The Lilac (Syringa) is treated slightly differently as it doesn’t regularly produce vigorous replacement growth from the base or lower branches. Instead, its extension growth which will produce next year’s flowers is produced on the perimeter of the permanent framework of older branches just below the current flowers. It is certainly worth removing spent flowers to prevent the production of seed but care must be taken not to damage the new shoots just below which would lead to reduced flowering next year.
That’s all for this month but I will be back in July with a main section on roses but will also include some thoughts on taking semi-ripe cuttings and autumn flowering bulbs. Just a reminder that June’s talk on the topics which I have covered in this blog is on Saturday 1st of June and July’s talk has been moved to Saturday 29th June to fit in with the ORL’s ‘Rose Week’. Both will be at 10am in the Wild Bird section next to the Pet section and as usual are free of charge. I hope to see you there.
Until then take care and enjoy your June garden and gardening.
Keith.