Artful gardening plays one quality off against another. Plants vary not just in the colour of their flowers but in the solidity of their structures and the shapes of their stems and flower heads. These qualities become clearer as they mature: a garden never stands still. My flower beds, therefore, change because one good idea suggests another. Their backbone could have been pre-drawn on a plan but their textures could not. They develop as the seasons pass. They never run as predicted.
In this developing variety, I value what I call flatheads, plants whose flowers are born in broad horizontality. Flatheads tango prettily with vertical spikes of flower, those important ingredients in artful summer borders, especially from July onwards. Thoughtfully planned plantings need to use a spiky uplift from plants like verbascums, which bring an upward dimension into flower beds. They then need to contrast with flat-headed companions.
I see the need, and now I have to carry it out more often. Otherwise my plantings will mature into clouds, clusters and what the great landscape designer Russell Page once called gaily coloured hay.
An obvious example of a flathead, a flat white, has just finished flowering in hedgerows and on bare ground. It is the elder bush, an uninvited arrival but a pretty presence in nature outside the garden wall. Its flat white flowers are also delicious when picked, boiled in water, strained and infused into puréed gooseberries as a base for homemade ice-cream. But they are not suitable for gardens as they seed and spread widely, even into the middle of other shrubs.
Here, I need to address some botany that is currently shaping fashionable advice for gardeners. Writers and lecturers recommend plants classed as umbellifers. Umbellifers hold flowers in umbels, usually on a hollow stalk from which the flower stalks branch out. A familiar example is another ubiquitous presence in hedgerows and uncut roadsides: cow parsley, Britain’s ultimate flat white. It looks prolifically lovely until mid-June but is messy and free-seeding thereafter. Keep classic cow parsley (Anthriscus sylvestris) strictly beyond your garden’s fence, but use it to understand the shape, stems and flowers of a true umbellifer.
Botanically, distinctions then become more complex. Umbelliferous plants are no longer in a family called umbelliferae: botanists have renamed it “apiaceae”. Plants whose names have the second word “umbellatus” are not always umbellifers, either. Examples include the fine blue or white-flowered Agapanthus umbellatus. That name is still in popular use but to complicate it botanists have renamed it “praecox orientalis”.
Umbellifers from the family of apiaceae are enjoying ever more attention. They fit into the mantra of rewilding and they also attract insects. Their flat heads of open little flowers are insects’ ideal landing pad. If I go into all the apiaceae available, you will drown in polysyllabic botanical names: Molopospermum peloponnesiacum is just one of them. Instead, an excellent survey and selection have been given by the expert Marina Christopher, admired for her adventurous Hampshire nursery, Phoenix Perennial Plants.
Google “Marina Christopher on umbellifers” and you will bring up her fine article in the magazine Gardens Illustrated. As she begins by explaining, there are about 3,000 species in the botanical family of apiaceae. At a simple level, there are carrots, dill, wild parsnips and myrrh, but others are poisonous. A garden museum of umbellifers would be unmanageably big and often undesirable.
Even the umbellifers she chooses as her top tips include ones that die out after flowering. They seed themselves prolifically and are not ideal guests. My shortlist of flatheads will be rather different. I will include umbellifers, but I will not be limited to them. I am concerned with aesthetics and ease of cultivation, not with a limit marked out by botany.
My top flat white is indeed an umbellifer, Selinum wallichianum. Its common name is milk parsley but who ever calls it that? It is at home in the Himalayas, looking good in Bhutan, not British hedges. Its finely cut lacy green leaves appear rather late in spring, but when the plant is established in a soil that is not too dry, it sends up reddish stems and flat heads of starry little white flowers from July until September at a height of about 3ft.
Bees visit it and insects love it, but it remains an unusual plant for gardeners, probably because it sets little viable seed and sowing it needs care, best described by Plant World Seeds, which supplies packets for £3.45, delivery extra. Make it better known; a fine flat white for the middle of a border.
I might have considered two other umbellifers, silvery-leaved Sessile and Daucus carota Purple Kisses, a most attractive wild carrot, but both are shortlived, one annual, the other biennial, dying in its second year. But instead I will abandon the apiaceae and choose a flat white lacecap hydrangea, fresh and arresting from late July onwards. Two excellent ones are macrophylla Fireworks and the taller Lanarth White, still only about 4ft high. They prefer soil that is not too dry and they retain their flat whiteness even on alkaline soil.
Breaking free of umbellifers, I will go for two fine flatheads, neither white. Tall yellow achillea used to be visible in every sort of garden, up to 5ft high and highly resistant to drought and frost. It has receded, perhaps because yellow in August is avoided by many planters, perhaps because it becomes hard to eradicate. I have swung back to it in these unpredictable summers and wonder why I was ever untrue to it. The tall one to get is Achillea filipendulina Gold Plate, a plant for big borders, one which never fails and is far taller and more impressive than other gold achilleas on the market.
I choose rose-red flatheads, the well-known sedums for autumn. Their horizontal flowers are highly attractive to butterflies, especially the migrants who descend on us so beautifully in the autumn months. Take your pick of reddish sedums, from Munstead Red to Autumn Joy, but be aware that they are now named hylotelephiums by botanists, a name that has not exactly swept the market. They grow so easily and their fleshy crowns exclude weeds.
Last, I go for a flat white shrubby viburnum, no umbellifer but exquisitely lovely in May when its horizontal branches are set with flat white flowers. Summer Snowflake is beautiful but is a large shrub. I prefer plicatum Watanabe, also from Japan, as it is about 5ft wide and as much high. It flowers from May onwards and carries the flat-white theme into shrubberies or open ground nearby.
My aim has been to nudge you to think horizontally and value the contrasts of upward and sideways structures in plants. The most famous books on garden borders are those on colour planning, refined with the art of painting in mind. The contrasts of shape, flatness and verticality attract less attention, but they underlie many plantings that look special, an artfulness we can all devise with umbels and much more.
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