February 28, 2014 5:45 pm

Gardens: why Britain’s mild winter has been great for some plants

‘The best viburnums have been in flower for four months and mahonias are enjoying a jubilee year’
Mimosa©Alamy

Mimosa in flower

If your garden is nearly under water, do not write it off. It is far too soon to say what will recover and what will not. I have seen some remarkable recoveries, even on ground soaked with seawater, and unless the floods hang around into late March, there will be as many recoveries as ever this time. Roses in particular are great survivors. So is grass, against most expectations.

Meanwhile, the unflooded have been enjoying an amazing year for winter-flowering plants. It will raise a wry smile in snowbound New York, but there has never been a better year for flowering mimosa in London. It has revelled in a non-winter and re-established itself as a bold choice of wall shrub or small tree for central Londoners. Last winter, the cold was extreme and the heavy snows looked set to break up the brittle branches. So much for mimosa, I told myself, but it has bounced back so brilliantly that I had to spend a morning last week on a mimosa-crawl between Chelsea and Notting Hill. More flowers than ever were visible over walls or on the sunny backs of tall houses. Trees which were cut down to the ground last February have rebounded even more quickly than stock markets since 2009. A bad winter kills the top growth, but often not the roots.

Acacia baileyana Purpurea©Clive Nichols/Gap Gardens

Acacia baileyana Purpurea

Mimosas are called acacias in garden lists, whereas the trees which are the acacias in Acacia Avenues are correctly called Robinias. A mimosa-acacia is a shrewd bet for anyone with a walled London garden which is buoyed up by the neighbours’ hot air. Two varieties are most often on sale and either will do an excellent job. Acacia baileyana is perhaps the more delicate in leaf and also comes in a golden-leaved and purple-grey-leaved form. The latter, Acacia baileyana Purpurea, is rather a favourite of mine, not brown-purple or sombre at all. The alternative is the Silver Wattle, familiar in the Antipodes, Acacia dealbata. It is nearly hardy and its leaves have a silver-grey tone to them. It prefers a neutral to acid soil, which abounds in London, and like its relations it is extremely quick-growing.

Mimosas need space, especially height. In a few years, winter permitting, they soar up to 12ft or so, but even then they cover themselves in their balls of scented yellow flowers. The supreme reason for having one in a sheltered garden is to be able to pick short stems of the flowers and have them indoors as a scented marvel on a table. They drop their yellow pollen all over the furniture, but the scent is divine. Thirty-five varieties are listed on sale in Britain nowadays, including one called Bushwalk Baby. Bailyeana and dealbata are the two best bets outdoors, lovely though many of the others are in leaf.

Daphne bholua Jacqueline Postill©GAP Photos/Marcus Harpur

Daphne bholua Jacqueline Postill

Here is another sight of the season. Time flies and it is now about 20 years since I first saw this great winter winner in the excellent Sir Harold Hillier Gardens near Ampsfield in Hampshire. It had originated in that great nursery and had been planted out into its collection of trees and shrubs in mown grass. So sweet and prolific were the flowers on Daphne bholua Jacqueline Postill that they announced their presence to ignorant visitors from a distance on a sunny February day. I think I remember writing that it made me want to turn a cartwheel in its honour. Since that encounter, this daphne has become widely available, although there has been a run on young plants this year. I can well see why. It is having a superb season, quite untroubled by the rains.

If you find a plant, buy it and plant it. It grows taller than many in the family, up to 5ft or so, and is not too bothered by alkaline soil. I have two. One is in an exposed site and has limped along, dying down to its base. It is still alive and flowering but the other is far happier. It is sheltered behind a box hedge which is about 5ft high and is flowering madly this winter, only its third in my garden. The leaves are not unduly special and in summer some of them turn yellow, but the flowers are a pale pink-white with a superb scent. I have just seen another at its best, so happy against a sheltering wall that it has self-seeded nearby, breeding two more bushes beside it. A west-facing wall is ideal for this excellent plant and as the bush is quite tall it can be surrounded with lower growing plants to flower in summer. Mine emerges from some hardy penstemons. It is amazing to realise that the basic bholua variety is at home in the Himalayas.

Viburnum x bodnantense Dawn©Anne Gilbert/Alamy

Viburnum x bodnantense Dawn

Beyond this daphne, viburnums have had their best winter ever. If you think the winter weather is going to recur, these superb winter shrubs are as good a buy as sandbags. In the old days they would flower in November and rapidly be hit by frost. They might try to flower again in February, but usually the frosts would hit the flowers all over again. The bushes themselves are completely hardy, but the flowers shrivel on a cold night outdoors.

This year those nights have been missing. As a result the best viburnums have been in flower for four whole months, a great gain from winter warming. The classic variety is Viburnum x bodnantense, and one which I most like is called Deben. It is named after the Suffolk river beside the headquarters of Notcutts nurseries where it was first selected. Deben grows very quickly and has flowers which open to a good white. Dawn, by contrast, is a sugary pink. I regard them as essential shrubs for any modern garden. Again, the short twiggy branches are good as cut flowers in small vases, although the scent is peppery if you investigate it closely.

Galanthus S. Arnott©Claire Davies/Gap Gardens

Galanthus S. Arnott

The natural pairs for these great shrubs are mahonias, also enjoying a jubilee year in the warm wet weather. Remember that their season can be prolonged by planting different varieties, Charity being a favourite, whereas Winter Sun comes on a little later with even brighter yellow better-scented flowers held in upright spikes. If British winters are going to abandon frost, there will be much to discover in outlying branches of this family. Several fine ones have recently been introduced from the wild, as yet of uncertain winter hardiness. One to look for is Mahonia pallida, as pale-flowered and delicate as its name suggests. It has slender lemon-yellow flowers and originates form Mexico. I expect it to be all over the British trade in the next few years.

Snowdrops are certainly all over the February newspapers. I cannot let them go unmentioned. The wet weather suits them, evidently, as they have had a magnificent February of flower. Experts now claim that they can be transplanted just as well in autumn as when they are in green leaf, but I am sticking to my old principle. Split the snowdrops now and spread them ever further when their leaves are visible and the flowers have just gone over. Then, you can see what you are doing. The range of named varieties is now bewildering and some of them are very expensive. If you want to start a sure-fire classy snowdrop walk, look for a pot of Galanthus S. Arnott. It is a great transplanter and worth the extra initial cost as it can be split up yearly and distributed all over a garden. This mild British winter has suited it, but it is just as good in a freezing cold year. Snowdrops are not called Snowdrops for no reason.

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