Pruning, just like watering and feeding, is part and parcel of general plant care. It’s also easy, as long as you know why, when and how to do it.
1. To rejuvenate: Pruning encourages new, healthy growth, which naturally means more leaves, flowers and fruit.
2. To tame space eaters: Plants like bougainvilleas and other wild creepers need to be pruned to stop them from growing into gutters or over telephone and power cables.
3. For shape and damage control: Trees and large shrubs that have been damaged can be pruned to get them back into shape. Young trees need to be pruned regularly to maintain a straight main stem and to produce a neat crown, and the low side branches of overgrown shrubs can be cut away to allow space for other plants to be grown beneath them.
4. For pest and disease control: If there is a crisis situation of some sort, you can prune away dead and heavily infected growth – which should be burned or destroyed immediately. Opening up or decreasing the size of an affected plant makes it easier to treat the plant with a fungicide or insecticide, and betters the coverage of these control measures.
5. To allow in more light: Where a huge tree casts too much shade, corrective pruning by sawing off the lower branches and even removing some branches inside its canopy can be done. It is especially deciduous trees that are bare in winter and are pruned for this reason, as it is easy to see in which direction the branches have grown and which can be removed without damaging the natural shape or weakening the tree.
Is there a ‘main’ pruning season’?
Winter is deemed to be the main pruning season by many gardeners, but while it is the correct time for some plants, folks who simply cut back all their woody shrubs are doing their gardens a disservice. Winter is the correct time to prune certain plants that flower on new growth produced in spring and summer such as roses, but one must keep in mind that some flowering shrubs, like spiraeas, weigelas, hydrangeas, deutzias, philadelphus and viburnums, bloom on hardened wood from the previous growing season.
A year’s pruning in a nutshell
For practical reasons, we’ve divided a year’s pruning for popular garden plants into four quarters. Putting the job off for a month is not going to make a huge difference to most plants.
1st Quarter: January to March
- Evergreen trees – remove low side branches.
- Climbers – stop fast-growing climbers like Boston ivy (Parthenocissus tricuspidata) and ornamental vine (Vitis coignetiae) from clogging gutters.
- Pelargoniums – cut them back in early autumn and use the prunings for cuttings.
- Evergreen hedges and shrubs – prune them all for neatness and shape in late summer, except those expected to flower or produce berries in autumn or winter like plumbago, tecoma and firethorns.
- Fuchsias – cut back and use prunings to make cuttings.
2nd Quarter: April to June
- Summer-flowering shrubs, climbers and perennials like bougainvilleas, cannas, heliconias, Michaelmas daisies, obedience plants, salvias, penstemons, yarrow (achillea) and chrysanthemums can be cut back or pruned in April.
- Cut off dead palm fronds and remove summer-storm damaged branches from trees.
- Prune plectranthus firmly back after flowering.
- Cut back perennial summer herbs to dry the prunings for winter.
3rd Quarter: July to September
- Deciduous fruit trees, blueberries and grape vines must be pruned in July. After pruning spray the dormant plants with lime sulphur. Prune peach trees only when already in blossom.
- Variegated plants like coprosmas – remove any green growth that appears suddenly, or the whole plant will revert to green.
- Tea and floribunda roses can be pruned from the end of July and into August. Get rid of dead, weak, or sick side branches and those rubbing against each other or crossing in the centre of the plant. If the form of the plant looks fine to you (it should have an open cup shape), simply prune the left over branches to about knee high.
- Plants like poinsettias, plumbagos, tecomas, hypericums, heliotropes, solanums, canary creepers, golden showers and buddlejas can be pruned in September when they have stopped flowering.
- Ribbon bushes, wild dagga and Cape mayflower (only after flowering) must be cut back to ankle level to renew.
- Tidy up bamboos and nandinas by cutting out old stems and cleaning up at their bases.
- Conifers grow actively in cooler months and can be lightly pruned to shape them neatly. Never cut into old wood, rather just shave off healthy foliage and growing tips with sharp secateurs or a hedge clipper – this will result in fresh growth.
4th Quarter: October to December
- Frost-damaged parts must be removed to prevent a disease from getting a hold on weakened cells. This must only be done after all danger of late frost is over.
- Clip off spent flowers and growth tips on azaleas.
- Shape citrus trees by removing excess growth and misshapen branches.
- By now, evergreens like buxus, durantas and syzygiums will sport lots of new growth, which allows you to prune them into different topiary shapes.
- Prune shrubs and climbers like jasmines that have flowered in late winter and spring.
- Prune back the side branches of hibiscus and tibouchinas to encourage lots of flowers in late summer and autumn.
- Prune banksiae roses.
- November is a good month for pruning proteas, pincushions, and leucadendrons, by removing all the old flowering stems and generally neatening the plants. Other fynbos plants, like confetti bushes and honey euryops, can also be pruned back.
How to prune?
Never try to prune without a plan. If you keep to the basic steps below you will save a lot of unnecessary cutting
- Get rid of dead, broken and diseased branches by cutting them back to a strong lateral branch. Ideally, this will result in a dense tree or shrub being thinned out sufficiently and not needing any further pruning.
- Next, the remaining side branches can be shortened to 2-3 buds or eyes, from which new growth will sprout.
- Keep the plant’s natural growth habit in mind while pruning, and stand back every now and again to check your work.
- Suckers sprouting at ground level or against the rootstock of a standard rose or grafted plant must be removed immediately.
- Use pruning tools that are disinfected, clean, sharp and designed for the specific task at hand.
Tool up with pruning tools
Quality cutting tools make light work of pruning. Buy the best quality you can afford, keep them sharpened, cleaned with disinfectant, and oil them before storing them.
Pruning shears: Pruning shears are only used to cut off small twigs (2-3cm thick), prune roses, take slips and cut flowers. There are many kinds available at prices that vary from dirt-cheap to very expensive. You will enjoy a lifetime of pleasure with top-quality shears, and you may even be able to approach the dealer for new spares or to sharpen the blades.
Branch cutter: A branch cutter has long handles and short parrot-beak blades for pruning away tree and shrub side-branches, and also reaching thicker side-branches of roses from a safe distance.
Hedge clippers: Hedge clippers have long, straight blades and are useful for soft hedging and making topiaries.
Bow saw or tree saw: This is the ideal tool for sawing off smaller tree branches. Heavy branches should rather be removed by a trained tree surgeon.
Safety glasses: Small pieces of plant material and even insects can land in your eyes while pruning, especially if you are working above your head, making safety glasses an important part of your pruning arsenal.
Garden gloves: Use thick gloves to protect your hands from getting blisters or against thorns.