Art of Pruning

Credit: Carolyn Herriot

Archway garden with climbing plants.

Archway garden with climbing plants.

Successful gardeners know the vital role pruning plays in creating the garden of their dreams.

Left to their own devices, plants follow their natural growth habit and assume the shape that allows them to make the best use of light, but this may not be what the gardener had in mind.

It’s always interesting to see how timidly gardeners approach pruning at first but how jubilant they become when they discover the creative control pruning gives them. That isn’t to say, however, that all pruning is beneficial. It breaks my heart to see a beautiful plant that’s been butchered by someone uneducated in the art of pruning. Botched jobs often leave ugly diebacks that not only ruin a plant’s aesthetic value but also invite disease.

Why Prune?

Gardeners prune for the following reasons:

• To train the plant
• To maintain plant health
• To improve the quality of flowers, fruit, foliage or stems
• To restrict growth
• To improve aesthetic value
• To repair damage or disease
• To prolong a plant’s season of interest

Appropriate Pruning Tools

Hand secateurs are designed for cutting stems up to 1.2 cm (3⁄4 in.) in diameter. Attempting to cut larger branches will risk making a poor cut or ruining the secateurs.

When a larger cut is needed, reach for loppers. They have long handles operated by both hands and can cut material 1.2 to 5 cm (3⁄4 to 2 in.) in diameter, or more if the wood is soft.

Pruning saws are useful for branches too large for loppers. They usually cut on the pull stroke, and cut faster and easier than a carpenter’s saw. (Bowsaws are good only where no obstructions exist for a foot or more around the area to be cut.)

When the cut required is out of reach, choose extendable pole pruners. These cut with a hooked blade above and a cutting blade beneath, similar to a large pair of loppers. The cutter is operated by pulling a rope downward. Poles can be fitted with an easy-to-attach saw, which I have found very useful for cutting larger, awkward-to-reach branches.

Hedge shears, manual or electric, are used mainly for shearing hedges and creating formal shapes in the garden. I use electric for large-scale jobs and manual for smaller ones. Use the proper tool for the job and don’t twist or strain it by trying to cut a branch that’s too big for the tool. Keep the branch to be cut as deeply in the jaws of the tool as possible.

TIP: Tempting as it may be, don’t ruin the blades by cutting wire with your pruning tools.

Care of Tools

If you want tools to last, keep them cleaned and well maintained during the gardening season. Wipe an oily cloth over blades, and keep edges sharp with several passes of a good oilstone. Once or twice a year preserve the wooden handles of tools by wiping them with a rag soaked in a mix of one part linseed oil and one part turpentine (paint thinner). Allow them to dry in the sun and repeat once more. Tools not only feel great after oiling, but the handles last longer by not drying out, cracking and breaking. TIP: For an easy way to clean tools, mix a bucket of clean washed sand with horticultural oil. When you’re finished using a tool, dip it in the bucket of oily sand before hanging it up. This cleans the tool and stops it from rusting at the same time.

Pruning Dos and Donts’

Do be clear about what you are trying to accomplish. Keeping your objective in mind while pruning will help you achieve it.

Do envisage the plant at maturity to determine whether your pruning plan is appropriate or not. It’s easier to plant something in scale than try to keep a large plant small. Remember that the more you prune, the more a plant grows. Heavy pruning produces water sprouts and an overabundance of soft wood.

Don’t prune so severely that it stunts the plant’s ability to thrive – never cut back more than 30 per cent at one time.

Do take stock of the overall effect of making major cuts. Caution now will prevent regrets later. You can’t stick it back on!

Don’t prune new growth early in the season. Food stored in roots and stems is used for the development of new growth. This is replenished by the food the foliage returns as a result of photosynthesis. If new foliage is removed too early in the season the plant may become dwarfed.

Don’t prune in late summer. This encourages new growth, which may not have time to harden off before winter, resulting in damage or severe winterkill.

Do keep in mind the two Js: January and July are the best months when it comes to clipping evergreen hedges and shrubs (such as cedars, laurels, cypresses). January produces new growth quickly; July allows new growth time to mature before winter.

Do prune ornamental shrubs at the right time. The rule of thumb is just after flowering. Spring-flowering ornamentals produce flowers on the previous year’s growth; if these branches are pruned the flowers are lost. Shrubs such as forsythia, philadelphus, weigela and lilac should be pruned in summer, after they have flowered.

Do make sure your pruning equipment is sharp to prevent unnecessary injury to plant tissues. Use scissor-type pruning shears rather than anvil-type ones.

Don’t buy cheap tools. You will get what you pay for and have to replace them. Buy good quality, which will last a lifetime if cared for.

Do start by pruning out the three Ds: dead, diseased and damaged wood. Avoid cutting too close and injuring the main stem/trunk. Then remove any one of two crossing branches that are rubbing. Removing branches growing into the centre keeps an open habit, beneficial for good air circulation and the penetration of sunlight. TIP: Pruning to an outward-facing bud or side shoot encourages outward growth. Cut immediately above a bud or side shoot, making a sloped cut away from the bud.

Don’t spread disease among plants; disinfect pruning tools between plants by spraying the tools with a 10 per cent solution of bleach from a spray bottle.

Do allow a plant to heal itself. Gone are the days when pruning cuts were covered with tar paste and pruning paint has been shown to slow down the healing process.

Do enjoy the new relationship you develop with your garden using proper pruning practices.

Carolyn Herriot owns The Garden Path Centre for Organic Gardening in Victoria (www.earthfuture.com/gardenpath) and Seeds of Victoria. She is author of A Year On The Garden Path: A 52-Week Organic Gardening Guide (ISBN 0-9738058-0-3)