GARDENING: Be a cut above when it comes to pruning

There’s an undeniable urge in autumn to wade into our overgrown ornamental borders, take the pruners to shrubs and any perennial judged in need of reduction, and afterwards admire the visual transformation.

By The Newsroom
Wednesday, 7th October 2020, 12:00 am
Tom festooning a long rose stem.
Tom festooning a long rose stem.

Put this thought into action and you might be making the kindest cut of all. But if the chosen plant was due to flower in winter or early spring, your mistake may well have robbed it of that pleasure.

Three variegated weigela are planted in different parts of the garden, and one has grown far too tall and wide since it flowered in June, but the leaves remain attractive. It`s a deciduous shrub so, as soon as they fall, we`ll step in with corrective pruning. All the stems removed will not be wasted. Some will be planted in the garden to root as hardwood cuttings.

This is a reasonable time to prune the buddleja, escallonia, lavatera, fuchsia, unless of course the latter three are still offering bloom as in this garden. Buddleja davidii, Lavatera `Barnsley` and hardy fuchsias all flower on new wood, putting on rampant seasonal growth very quickly. This encourages us to reduce them drastically in size just as spring arrives. To avoid two potential problems with the taller of these shrubs, i.e. wind rock and frost damage, I adopt a simple pruning strategy. They`re pruned in stages. Reduced to half a metre now to prevent wind purchase that loosens the root system, then further down to lower shoots when the risk of severe frost has gone.

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Wind rock can also affect roses with tall stems, but there`s an alternative to pruning. Bend the branch over into a loop and secure it to the plant base or a cane. This is festooning, a ploy also used to encourage apple branches to bear flowers and fruit.

Shrubby hydrangeas need a little thought before pruning. There`s an advantage in leaving faded blooms on the plant over winter because this helps protect next year`s embryo flower buds against frost. It`s not unusual to have a lean flower year following a severe winter.

This is not the time to be pruning ornamental trees or shrubs that are adapted to winter flowering. It`s self-evident with viburnums because they`re already in bloom, but several have not started yet. Golden jasmine flowers will not appear until leaf fall. I`m not trimming stems currently tumbling over a pathway, rather waiting so they can contribute to a vase.

Hedges should be set up for winter by now. Some such as privet needed a second, late trim, given that the next one will be in late June when garden birds will have finished nesting.

There`s not a hint of blossom yet on the winter cherry, Prunus `Autumnalis Rosea` but it`s resided here three decades so we know it will happen. It`s pruned every few years to keep it in check, but as with most winter flowering and foliage plants, constant snipping stems for vases maintains the status quo.

Bark on the trunk of a silver birch has been cloaked by a mass of shoots that appear each summer, and to remove them then would have caused a `bleeding` of sap. Once leaf fall is done and dormancy arrives, we`ll remove them all and enjoy the transformation.

Hardy herbaceous border plants do not present such a dilemma. When the stems of echinacea, rudbeckia, Michaelmas daisy and others expire, and the perennial root system goes into a state of semi-dormancy, all top growth can be cut to ground and composted. However, there are cases where leaving this intact is worthwhile. If for example, attractive seed heads or capsules have formed on teasel (dipsacum), poppy, achillea and others, they add winter interest especially when adorned with frost. They can also be used in floral arrangements.

A surplus of seed heads and fruits can make a significant difference to the chance of birds and insects surviving winter. Having an excess of self-sown plants emerging around the garden every year is a small price to pay for such benefits. Satisfying though it is to have a neat, tidy garden, think of other living organisms, some unseen, that share it you. Think biodiversity!