A crocosmia coup and other mysteries of the gardening cosmos

What can we learn from the past? As a historian, I engage weekly with this question. As an investor, what I learn from it is that I repeat mistakes. As a gardener, I am wary of learning too much.

The past year left a mixed legacy for learners. In Britain, it was friendly to gardeners from spring until mid-autumn. They were lucky, as drought, fires and gales battered many gardeners elsewhere. In Sicily, there was next to no rain from spring until late autumn and even the island’s wild cyclamen carried only about one-tenth of their usual flowers.

Befitting a year of widespread drought, the UN General Assembly declared 2023 the International Year of Millet, the grain which grows well in dry conditions and yields a healthy crop. Gardeners who like grasses have yet to latch on to the stems and seeds of the many types of millet, especially the Japanese ones. In a warming world it will have an important agricultural future, but it looks too brown and dreary for my garden’s main sightline.

In Britain the climate, as usual, was the main imponderable, making learning from it difficult. I never remember a year with such contrasting weather. In January, sharp frost inflicted acute damage on gardens, but its effects were sporadic. In London, many gardeners missed the worst of it. My urban benchmark is my daughter’s garden north of Paddington. I class abutilons with tender mallows and in my cold garden in the Cotswolds both of them die as soon as the temperature lurches below zero. In hers, the excellent Abutilon Canary Bird is still 7ft high, covered in hanging yellow flowers. It is near a wall, but is not tied to it.

Clearly it is a superb fast-growing shrub for a sunny London garden, especially as it allows lower plants to flourish under its light canopy of branches. I did not introduce Canary Bird to my daughter: in my garden it would be a corpse.

Outside London, gardeners in early 2023 lost far more than their Canary Birds. By late March it was obvious that many hebes, cistuses and ceanothuses were dead from top to bottom. For the past 30 years, one of my garden’s early delights has been the wonderful Daphne Jacqueline Postill, up to 6ft high and covered with scented lilac-pink flowers even on alkaline soil. I have recommended it here since first seeing it in flower in the Hillier gardens in Hampshire, a fine place to visit in order to assess winter-flowering shrubs. The tall stems on my Jacqueline Postill became a black mush in February and, to my horror, the entire plant is dead. This loss has been widely shared in exposed gardens and will take years to repair.

Even so, other losses were sporadic. In autumn 2022, I failed to lift all my dahlias and store them according to the old rule in boxes in a frost-free place. This spring, I assumed they were not just missing but dead in the ground, so I ordered many more. Most of the dahlias I had left unlifted then sent up new shoots in June and gave me a dahlia fiesta in early September until heavy rains later in the month ruined their flowers, along with the Michaelmas daisies.

Why did the dahlias’ un-hardy tubers survive the winter when much else did not? My theory is that the cold nights were particularly deadly to evergreen plants, whose stems were soaking wet from the previous Christmas rains. Myrtles, daphnes and even rosemary were iced through, being so wet already all over their top growth. Dahlias, by contrast, were 6 inches or more underground without any branches showing. Even so, I am surprised: alternative answers are welcome. I like mine because it accounts for the survival of most of the agapanthus and crocosmias.

In pots, agapanthus are more vulnerable and indeed my white ones turned to a soggy mush and died. In open ground they survived, as did all the crocosmias. So many new ones have been bred and selected in both families, often hardier than their parents. In the 1960s, crocosmias were regarded as a major risk, marginally hardy in Britain, but in the 2020s we know better. They like sharp drainage, responding well to plenty of grit dug round them. They also revel in plenty of water.

Here, 2023 obliged them. It was a rotten year to be a crocus in flower, whether in wet February or in wet November. It was an ideal year to be a crocosmia, because regular rains in summer gave its corms the moisture they appreciate. The plant of the year in my garden was smouldering red Crocosmia Emberglow as it flowered more freely than ever, closely followed by tall Lucifer and the vivid yellow Paul’s Best Yellow.

I was not alone in enjoying a crocosmia coup. When I visited Keith Wiley’s superb naturalistic garden, Wildside in Devon, he had planted drifts of crocosmia down the slopes of a newly made landscape, which was planned to evoke South Africa. They too were having a vintage year.

It was a rotten year to be a crocus in flower, whether in wet February or in wet November. It was an ideal year to be a crocosmia, because regular rains in summer gave its corms the moisture they appreciate

So were many annuals, infilling for winter’s killings. Half-hardy ones missed the frost, because they were bedded out in late May. Then the frequent rain showed how strong and vigorous they can become when constantly watered. In 35 years I have never had such tall, thick-stemmed cosmos daisies, annuals often seen as far afield as India. They are not the drought-loving plants which their presence there implies. As my garden drains quickly, frequent rain showers activated the cosmos’ roots. They did the same to tall tobacco plants, never so good before. Persistently wet summers are widely considered to be unfriendly to annuals, but the beauty of 2023‘s summer was that the rain was intermittent, usually falling between sunny days with sufficient cloud to keep off a repeat of 2022’s high heat.

Who could have guessed as much from the recent past? The year before last was burning hot and a severe trial for gardeners. The lesson seemed to be that fleshy-leaved, sun-loving bedding plants would now be the best choices. In 2023, the lesson was refuted in Britain. The same was true in borders. The year before was an awful year for border phloxes, but in the cool wet months of summer 2023 they were superb.

After 2023’s killing cold, I started by vowing I would henceforward play safe. I had even lost young buddleias so, in future, I told myself, I would plant utterly hardy japonicas, weigelas and philadelphus. Has the lesson been well learnt? Since October the British non-winter has been amazingly mild, wet and frost free and refuted it. Of course it points to wider problems in the global climate but locally, in our home British gardens, it has been so kind. In spring I had vowed never to plant a ceanothus again, except on a south-facing, sheltered wall. I am now thinking of Ceanothus Gloire de Versailles as a quick-growing backbone for a summer border. About 6ft high and covered in pale blue flowers, it has been the glory of many borders in Hampshire until winter 2022/23.

Am I too old to learn, or is the evidence too confused for one-sided decisions to be sensible? I prefer to draw a different lesson, that gardening, especially in Britain, is inherently unpredictable, a reason why we never tire of it and why one hard winter never ends by curbing hope. What ever will 2024 bring to this column? Happily, I cannot say for sure.

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