Fine-pruning

Robin Lane Fox in the Sir Harold Hillier winter gardens

In a high wind in Hampshire I have just been back to school. When the great gardening writer Vita Sackville-West was awarded the RHS’s famous Victoria Memorial medal, she reacted by enrolling herself in a weekly correspondence course on gardening. I am not sure I trust the mail to send my assignments on time. So I have been out for an early morning practical in one of the best winter gardens in modern Britain.

In December 1996, the Sir Harold Hillier Gardens near Ampfield, in Hampshire, opened their newly-planned winter garden, the complement to their new education centre. The surrounding gardens are the creation of the king of hardy shrubs, Sir Harold Hillier, who planted them with the pearls of his collection and even some of his surplus nursery stock in the post-war decades. Admirably, Hampshire County Council took over the running of this extraordinary asset upon Sir Harold’s death in 1985 and has kept them in shape for the fee-paying public ever since. I fervently hope that the gardens will not now be let loose on the mercies of the Big Society. They are a beacon for all lovers of rare trees and shrubs in southern Britain and I do not believe that volunteers could cope with their living heart.

Looking at their foundation plaque in a morning gale, I had two reactions. Since 1996, why have I not made an acre or two of similar winter planting, as it is so easily maintained and such a delight in the first two dark months of the year? The Hillier winter garden looks enviably mature already.

Our serious instruction began that morning in the living laboratory: the winter garden itself. Barry Clarke is a top Hilliers nurseryman and 15 of us were lucky to have him as our teacher for four hours. He explained things which I perhaps knew already – how to prune a dogwood or what to look for in an Acer griseum. However, I did not know that the most vivid of the orange-and-pink stemmed dogwoods is Cornus sanguinea Anny’s Winter Orange. I think I knew that all cornuses with coloured stems should be cut right down to the base every single year and then mulched with manure and a dash of fertiliser, not too close to their main stump. I may know that trick, but I do not always apply it. Try it in a fortnight’s time. I have now seen what a difference it makes to the colour of the next season’s stems on Cornus alba Sibirica, the best of the scarlet-reds, and fiery pink and yellow Midwinter Fire. We pupils did some helpful cutting back, with permission to take the long hardwood cuttings away and try to root them in deep pots of soil with at least four inches of stem under ground. There are two good pots of Anny’s elusive winner now outside my back door.

I grow hellebores, of course, and indeed I cut off their old leaves in autumn to prevent the spread of black spot disease into the centre of the plant. However, I had no idea how best to fertilise a hellebore and produce new hybrids of my own. It is even easier than fertilising a lady. Find a fully open flower whose male stamens are fluffy with pollen. Pick it, take it over to another flower which is beginning to open and dust the pollen into the sticky centre, the female stigma. Leave that flower to open but mark it with a label or coloured tie. It will set seed which you can collect and sow in a pot. It will probably germinate and then you have your own little creation, to be named FT House or FT Home.

Again and again Clarke showed us how spring bulbs will flourish if planted well within the span of branches on early-flowering trees and shrubs. Winter irises are happy under weeping Cercidiphyllums, and a gorgeous carpet of cyclamen and snowdrops will run far closer to a maturing hornbeam than I would ever have risked. The bulbs are dying down when the tree comes into leaf and starts to cast shade. I have been far too timid in this department.

The Hillier Gardens have superb witch hazels: will they only grow on acid soil, fit for azaleas? I am still wary of them, but Clarke is adamant that they flower well in his chalk garden. The one loss is their autumn colour, often a bonus on acid soil. I like the pale yellows best, not the orange-rusty ones with names like Ginger Biscuit. Barry insisted that the best is a spreading flat-topped one called Aphrodite. I had started to believe his every word, although Aphrodite has bronze-yellow flowers.

I even learned when to prune these witch hazels, which surprised me so much I will hold it over for another day. After three more hours of competitive note-taking we split into groups for the moment of truth: winter pruning of fruit trees. I will admit that I have never done it and I certainly did not know that cherry trees, but not apples, are best pruned in late spring. Clarke showed us how to saw and cut, making effortless undercuts and never sawing flush to a main trunk, but always allowing a collar of protruding growth to harden over. It was then over to us on a tangled Malus Cowichan and an ancient apple which even he described as “sad”.

There is something unnerving about muscular women armed with toothed hand saws when they outnumber the alpha males in their group. I still do not know how to saw overhead without getting sawdust in my eyes and hair. The females were showing no mercy and within minutes we had a heap of apple prunings on the ground. I am feeling bad about my under-cut. It left the apple looking even sadder than when we first attacked it.

Iron, says the inimitable poet Homer, draws a man on. After undercutting the Malus we were let loose to cut the smoke-bushes and a purple-leaved ornamental elder on the approach-route to Hilliers’ main shop. Gleefully I showed no mercy. Elders seed into impossible bits of my walls and boundaries, so it was a delight to give an elder hell with Clarke’s approving permission. If it looks more purple-leaved than ever this summer, remember what it owes to my savagery.

Indoors we regrouped for invaluable tips on rooting cuttings after a masterclass in planting trees on light soils. If the standard of practical advice in this column is noticeably higher this summer, you will know to credit Clarke. I am newly addicted to practical courses. On February 24, there is even a talk in the Hillier Gardens called “Wildebeest in the Potting Shed”. I am not enough of an enthusiast for that one. Instead I will be practising Clarke’s wisdom on hardwood cuttings while continuing the campaign against “Squirrels on the Loose”.