Pruning, Done Right

With the price of fruit at an all-time high, having your own fruit trees is becoming more and more attractive. If you'd like to get a new tree planted, read on. Or if you're lucky and you’ve inherited an old fruit tree at your place, it might have been neglected; chances are it will really reward you after a little bit of TLC.

Why Should I Prune?

Flowering shrubs are pruned to encourage a prolific show of blooms every year; also to maintain their size and shape for aesthetic enjoyment.

Fruit trees, grape and kiwifruit vines and berry canes are pruned to maximise fruit yield and enhance disease resistance. For this article, we’ll be focusing on pruning fruit trees; vines and canes need slightly different pruning techniques.

• Juvenile fruit trees and vines are pruned to train their branches into the right direction and shape: it’s less stressful for the plant if light pruning is done gradually, year on year. For the first 4 years of a tree’s life, training and shaping it are more important than fruit production, so keep your fruit expectations low at first.
• For smaller home garden sized pipfruit (apples and pears), we recommend training in a ‘central-leader’ style, where a single strong vertical trunk (leader) is established, with tiers of fruit-bearing branches radiating out from it. This method styles trees into a practical pyramidal shape that saves on space.
• The traditional training method for larger orchard-sized pipfruit or stonefruit trees is to encourage about 4-7 strong leaders into an open ‘vase’ shape (with no central leader), that lets light and air into the centre of the tree. If you’re pruning a mature vase-trained tree without a central leader, the object is to keep the centre of the tree opened up to the light.
• Mature fruit trees always benefit from a prune if they have dead or weak branches, crowded dense foliage, branches crossing over each other, or they’ve grown too large for their space. In these situations, pruning boosts the health and resilience of the tree, improves resistance to high winds and can dramatically increase fruit harvests.

What to look for: targets for pruning and different types of buds

The Science^™ Part: Understanding Bud Growth

The first fundamental is getting an understanding of how plants grow – so you know which parts you’re chopping off! Almost all trees and shrubs form their new growth from buds. There are 3 main types of buds:

Dormant Buds – these buds stay dormant through their first season, until the next season when they grow into stems, leaves or flowers. There are different types of dormant buds, outlined below.

• The most important bud for our purposes is called a ‘terminal bud’. One of these will form right at the end of each branch, at the growing tip.
• Terminal buds are dominant over all the other types; this is known as ‘apical dominance’. Terminal buds produce auxins (a type of plant hormone) that suppress the growth of all the dormant buds lower down the branch, in favour of the growing tip. If we prune the branch back to just above a lower side shoot (where the branches form a ‘Y’ shape), it allows the roots of the plant to supply cytokinin (another plant hormone) to the side shoot, which in turn triggers the dormant bud on the end of that side shoot to start growing, taking over the role of the dominant terminal bud. This type of pruning cut is called ‘thinning’, which is the recommended method for pruning most trees and shrubs, because it preserves their natural shape and size.
• A ‘leaf bud’ is a flattened triangular looking bud on the side of a branch. If the branch is pruned just above the bud, it’ll sprout a new leaf.
• A ‘flower bud’ is a rounded bud on the side of a branch, that forms into a flower. In spring these are the first buds to swell and plump up.
• A ‘spur’ refers to the little twiglets that sprout from the older wood branches in lots of fruit trees. These also form flowers and fruit, so don’t trim them off!
• A ‘bud scar’ is a ring mark around a branch, where a terminal bud started growing after the dormant season. It’s a convenient way to see where this year’s growth started.

Latent Buds – if a dormant bud stays dormant, just sits there and doesn’t wake up for multiple seasons, they’re called latent buds. Latent buds are like plant insurance: if the branch above the bud is broken or cut, the latent bud can spring into life and form a new side shoot.

Adventitious Buds – these buds develop out of a completely new spot; usually where a branch has been damaged or pruned poorly. Unfortunately, they don’t form branches with a strong bond to the tree, so they break off quite easily.

• If you prune and leave budless lengths of branch sticking out, you encourage adventitious buds to form and shoot sideways from the branch. That’s why we prune down to just above a growing shoot and don’t leave stumpy bits of branch behind!
• This style of pruning cut is called ‘shearing’ (or ‘heading’ if it’s a good-sized branch of a tree). Because it encourages an excessive amount of new foliage to form below the cuts, it’s usually only recommended for clipping hedges or topiary.

Stem pruning visual guide

Where Should I Prune? Cuts and Healing, Explained

Time for another fundamental! When you’re pruning, you are actually wounding the plant; it’s best to do it in a way that allows the plant to heal as quickly and efficiently as possible. Woody plants are quite capable of healing themselves, so the trick is to cut in the particular spot that has the highest concentration of natural healing mechanisms.

• If you’re pruning off an entire branch, the ideal location to cut is at the ‘collar’, the elbow where the branch joins the main trunk. Easily identifiable by the ridged or wrinkled texture of the bark, the branch collar is where the healing magic can happen, thanks to the meristematic tissue located there. The place to cut is at the outside of the branch collar, not right up flush against the trunk (cutting flush removes the natural healing tissue and makes the wound bigger than it needs to be). Over time, a doughnut of protective bark callus forms around the cut and eventually closes up completely.
• An old-school trick to ensure fast-healing cuts is to cut off large branches in sections. If you saw a branch with its full weight levering against the tree, when you get towards the bottom of your saw cut, the branch usually gives way and rips a ragged strip out of the bark at the bottom of the cut. If you saw through your first cut 10cm away from the branch collar, then make your final cut in the correct spot just outside the branch collar, there isn’t so much weight bearing down on the cut - so you can make a neat and tidy job.
• When pruning stems, the perfect spot is where the bud or leaf emerges. Stem structures can be arranged in two patterns; alternate or opposite. Fruit trees and roses have alternate buds, so the best location for the cut is just above an outward-facing bud at a 45-degree angle, as in the diagram above. This prevents water pooling on the top of the cut stem and on the bud itself. The base of your bud should more or less be in alignment with the base of your cut on the opposite side.
• If you’re pruning an opposite patterned plant with the two shoots positioned exactly opposite each other on the stem, then the best cut is straight across above the junction of the two shoots where there are two healthy buds just waiting for their turn to grow.
• It’s always a good idea to eliminate ‘suckers’. These enthusiastic vertical shoots appear right at the base of the plant and originate from the roots, or from just below the bud union (the bumpy grafted bit at the base of the main stem). If you spot a sucker popping up out the soil, you’ll need to dig out the soil around it, then clip the sucker off at its base.
• Pruning causes stress to plants, so make sure to reward them with water, feed and mulch once you’re done.

A great solution to prevent pathogens entering the fresh cut is to apply Yates PruneTec pruning sealant. PruneTec encourages natural healing and forms an elastic, UV-stable barrier that stretches as the plant grows. It’s a trusted favourite in the horticulture industry; applying PruneTec protection after pruning is standard practice in commercial orchards and vineyards.

An apple tree with Yates PruneTec applied to seal the pruning cut, with natural healing callus beginning to develop. Note the branch collar, visible around the cut.

When Should I Prune?

The general rule of thumb is to prune shortly before new growth begins. This means winter is the peak time for pruning deciduous trees and shrubs, while they're leafless and it's easier to see what needs to be pruned. In cooler areas it’s best to wait until late winter, in areas with no frosts you can begin to prune in mid-winter.

• Winter pruning promotes fast regrowth in spring but be careful not to prune too early: this can encourage a flush of pre-spring growth that’s vulnerable to frost damage. Pruning fruit trees in autumn can really set back progress in spring.
• Summer pruning during peak growth time can also delay development by reducing leaf cover; this cuts back the trees nutrient production.
• Summer is still a great time to remove dead branches however, because they're easy to see against the foliage.
• There are a few things on the hitlist that can be pruned any time (as soon as you spot them): suckers; water sprouts; or branches that are dead, diseased, or damaged. Check the diagram above to identify them, then get the secateurs out!

Spring-flowering trees and shrubs need a different approach: prune right after they finish flowering.

Summer and autumn blooming trees and shrubs are best pruned in late winter or very early spring, before their annual growth begins in earnest.

When fruit trees and roses have dropped their leaves and entered winter dormancy, it's highly recommended to give them a clean-up spray of Yates Lime Sulfur. It forms a protective film of sulfur which prevents disease pathogens getting started. It also controls scale and mite pest insects, to give the plant a flying start in spring.

Stay Sharp!

Keeping your pruning tools sharp and well-oiled makes them nicer to use, gives them a much longer lifetime and saves your wallet over the long term.

Select the right-size tool for the branch you’re pruning, to avoid damage to the plant (and the tool):

• Secateurs or pruning shears work best on the smallest branches (bypass-type secateurs make the neatest cuts and won’t cause crush damage).
• Use loppers on branches 2 – 3cm in diameter.
• Use a pruning saw on branches larger than 4 – 6cm in diameter.

Keep It Clean

It’s good practise to clean secateurs and other pruning tools between plants, to avoid spreading disease-causing bacteria and spores from one plant to another. It’s vital to clean tools after removing any plant parts infected by a fungal disease.

The best way to clean is to wipe the tool blades with methylated spirits, bleach, or alcohol wipes, then rinse with water.